Surface polymers of at least two polymer molecules and methods of forming the same

Abstract

Disclosed herein are surface polymers on substrate surfaces, the surface polymers being composed of at least two polymer molecules, and methods of forming the same. These surface polymers may be formed on a substrate surface by forming first polymer molecules from first polymerization initiators attached to the surface of the substrate, and subsequently forming second polymer molecules from second polymerization initiation sites on the first polymer molecules.

Description

[0001] Docket No. RAD-007WO Surface Polymers of at Least Two Polymer Molecules and Methods of Forming the Same

[0002] Cross-Reference to Related Applications

[0003] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 651,781, titled “Micron-scale surface polymers on substrate surfaces and methods of forming the same,'’ filed May 24, 2024, and U.S. Provisional Patent Application No. 63 / 765,068, titled “Surface polymers composed of at least two polymer molecules and methods of forming the same.” filed February 28, 2025, the entire contents of each of which are incorporated by reference herein.

[0004] Field

[0005] Disclosed herein are surface polymers on substrate surfaces, the surface polymers being composed of at least two polymer molecules, and methods of forming the same. These surface polymers may be formed on a substrate surface by forming first polymer molecules from first polymerization initiators attached to the surface of the substrate, and subsequently forming second polymer molecules from second polymerization initiation sites on the first polymer molecules.

[0006] Background

[0007] Well-defined polymeric structures on surfaces have become increasingly important in many technologies and applications. “Surface polymers”, “surface bound polymers” or “polymers on a surface” describes a polymeric structure having polymer chains that are chemically bonded to a surface at one end through covalently bound polymerization initiators. Two methods, known by persons skilled in the art, can be used to achieve such polymeric structure, namely the “grafting to”-approach and the “grafting fronf’-approach (See Fig. 1 and Fig. 2). In the “grafting to” (Fig.

[0008] 1), polymers are pre-prepared in solution and then deposited onto the surface in question, since the pre-prepared polymers are designed in such a way that one of the chain-ends has some affinity for the surface of interest. Upon contact with the surface of interest, the polymers will selfassemble on said surface forming surface bound polymers. In the “grafting from” approach (Fig.

[0009] 2), small molecules capable of acting as polymerization initiators are covalently bound to the surface of interest in a pre-polymerization step. Subsequently polymerization is initiated via the polymerization initiators. Accordingly, surface polymers are formed from the surface.

[0010] While the “grafting to” approach allows for simple preparation procedures and detailed characterization, in that one can prepare the polymers using conventional polymerization methods and store those polymers before initiating the self-assembly procedure, the “grafting to”-approach IPTS / 128973811 1lacks the ability to form high density surface bound polymeric structures. Main equilibrium conformation of long polymeric structures in solution is a contracted, or a coiled polymer chain, unless the polymer solution is extremely diluted with highly solvating solvent or other means employed to stabilize extended conformation (e.g., pH for ionic polymers). Such extra means to stabilize extended poly mer chain conformation may complicate and interfere with the “grafting to” process conditions and make the approach less practical. Therefore, the self-assembly process is being halted by the steric repulsion between the coils of pre-made polymer chains as they selfassemble on the surface leading to loosely packed polymer coils on the surface (see Fig. 1). The “grafting from”-approach allows for the formation of highly dense surface bound polymer structures, as the small initiating molecules can form a much more densely packed layer on the surface (compared to large polymer molecules, see Fig. 2). Such a densely packed layer of initiating molecules is guiding monomer molecule-by-monomer molecule formation of polymer chains, where the extended conformation of growing polymer chains is sterically stabilized by their close proximity to each other. As such, the surface bound polymer structure formed by a “grafting from” approach results in a much higher density of polymer chains. Additionally, as the “grafting from” approach allows for highly dense surface bound polymer structures, a brush-like structure can be achieved, thus, the name “polymer brush”. In these structures, the polymers are stretched and forced to stand upright due to the steric repulsion between neighbouring polymers creating a unique structure known by people skilled in the art as a “polymer brush” structure. On surfaces, these structures are tethered / attached, usually covalently, at one end to the surface, typically to a solid or semisolid surface, thereby differing from polymers formed in solution and subsequently deposited onto a surface.

[0011] As mentioned above, surface polymers are prepared by one of the following two main strategies: “grafting to” or “grafting from”. In the “grafting to” approach, polymer chains are deposited onto the surface in question. The “grafting to” approach suffers from several drawbacks and limitations making it difficult to produce thick and dense surface polymers. In the “grafting from” approach, the surface polymer growth (surface polymer chain propagation, extension of the chain by monomer units) is initiated from initiator-functionalized surfaces, using, for example, a controlled / ”living” polymerization technique, such as anionic polymerization, cationic polymerization, ring-opening polymerization, and controlled radical polymerization.

[0012] Surface polymers formed may form complex structures depending on monomeric building blocks used for the polymerization. In some applications, thick surface polymers are desired, however, it IPTS / 128973811 1has proven difficult to prepare thick surface polymers using a “grafting from'’ approach. Thus, there is a need for methods making possible preparation of thicker surface polymers.

[0013] Summary

[0014] In an aspect of the disclosure, a substrate having a surface polymer on a surface of the substrate is provided, the surface polymer comprising first polymer molecules covalently bonded to first polymerization initiation sites on the surface of the substrate, and second polymer molecules covalently bonded to second polymerization initiation sites on the first polymer molecules, wherein the average dry film thickness of the surface polymer is at least 0.5 pm. In an aspect of the disclosure, a substrate having a surface polymer on a surface of the substrate is provided, the surface polymer comprising first polymer molecules covalently bonded to first polymerization initiation sites on the surface of the substrate, second polymer molecules covalently bonded to second polymerization initiation sites on the first polymer molecules, wherein the first polymer molecules, and / or the second polymer molecules comprise copolymers. A substrate further comprising third polymer molecules covalently bonded to at least third polymerization initiator sites on the second polymer molecules may be provided. The third polymer molecules may be bonded covalently to some first polymerization initiator sites and / or some second polymerization initiator sites. A substrate further comprising fourth polymer molecules covalently bonded to at least fourth polymerization initiator sites on the third polymer molecules may be provided. The fourth polymer molecules may be bonded covalently to some first polymerization sites, some second polymerization initiator sites, and / or some third polymerization sites. The average dry film thickness of the surface polymer may be at least 0.5 pm. The average dry film thickness of the surface polymer may be at least 1 pm. The substrate may be such, wherein a ratio of the first polymerization initiators on the surface of the substrate to non-polymerizing initiator sites on the surface of the substrate may be controlled within a certain range. The ratio of first polymerization initiators to non-polymerizing initiator sites on the surface of the substrate may be 1 : 1 , 1 :25, 1 :40, 1:50, 1:75, 1:100, or 1:200. Each of the first polymerization initiator, the second polymerization initiator, the third polymerization initiator, and the fourth polymerization initiator may independently be selected from 2-bromoisobutyryl bromide (BiBB), p-tchloro-methyl)phenyltrimethoxy silane (CPTMS), and chloromethyl (CM) moiety. Each of the first polymer molecule, the second polymer molecule, the third polymer molecule, and the fourth polymer molecule independently may be selected from poly(2-hydroxyethyl methacrylate) (PHEMA), poly(glycidyl methacrylate) (PGMA). poly(n-butyl methacrylate) (PBuMA), poly(tert-butyl methacrylate) (PtBMA), poly(benzyl methacrylate) (PBnzMA), poly(2-ethylhexyl IPTS / 128973811 1methacrylate) (PEHMA), poly(2-hydroxylethyl acrylate) (PHEA), and polystyrene (PSt), or a combination thereof. Each of the first polymer molecule, the second polymer molecule, the third polymer molecule, and the fourth polymer molecule may independently be copolymers. The first polymer molecule may be poly(2 -hydroxyethyl methacrylate) (PHEMA) or polystyrene (PSt). The second polymer molecule may be a copolymer of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(benzyl methacrylate) (PBnzMA), poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(n-butyl methacrylate) (PBuMA), poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-ethylhexyl methacrylate) (PEHMA), poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl acrylate (PHEA), or poly(2-hydroxyethyl methacrylate) (PHEMA) and polystyrene (PSt).

[0015] In an aspect, a surface polymer formed on a surface of a substrate may be provided by providing a substrate, exposing the substrate to a first polymerization initiator, exposing the substrate to a first monomer, exposing the substrate to a second polymerization initiator, and exposing the substrate to a second monomer. Providing the surface polymer may further comprise exposing the substrate to a third polymerization initiator, and exposing the substrate to a third monomer. Providing the surface polymer may further comprise exposing the substrate to a fourth polymerization initiator, and exposing the substrate to a fourth monomer.

[0016] In an aspect, a surface polymer may be formed on a surface of a substrate by exposing a substrate to first polymerization initiators covalently binding to a surface of the substrate, exposing the substrate to a first monomer to form first polymer molecules from the first polymerization initiator sites, exposing the substrate to second polymerization initiators covalently binding to the first polymer molecule, and exposing the substrate to a second monomer to form second polymer molecules from at least the second polymerization initiator sites. The surface polymer may be formed by further exposing the substrate to third polymerization initiators covalently binding to at least the second polymer molecules, and exposing the substrate to a third monomer to form third polymer molecules from at least the third polymerization initiator sites. The surface polymer may be formed by further exposing the substrate to fourth polymerization initiators covalently- binding to at least the third polymer molecules, and exposing the substrate to a third monomer to form fourth polymer molecules from at least the fourth polymerization initiator sites. The surface polymer may be such, wherein one or more of the surface polymer molecules are copolymers. The surface polymer may be such, wherein the surface polymer molecules formed on the substrate have an average dry film thickness of at least 0.5 pm. The surface polymer may be such, wherein IPTS / 128973811 1the polymer molecules formed on the substrate have an average dry film thickness of at least 1 pm. The surface polymer may be such, wherein each of the first monomer, the second monomer, the third monomer, and the fourth monomer independently may be comprised in a reaction composition comprising a catalyst, a ligand, an activator, and a solvent. The catalyst may be obtained from Cu, Fe or Ru. The ligand may be selected from N,N,N’,N”,N”,-penta-methyldiethylene-triamine (PMDETA), tris [2-(dimethylamino)ethyl] amine (MesTREN), tris(2-aminoethyl)amine (TREN). tris(2-pyridylmethyl)amine (TPMA), 1,1,4,7,10,10-hexamethyl-triethylenetetramine (FIMTETA), tetramethylethylenediamine (TMEDA), 1 ,4,8, 11 -tetramethyl -1,4,8,11-tetraazacyclotetradecane (MeiCyclam). and / or 2,2'-bipyridyl (BiPy). The activator may be selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glycose, glucose with GOx. and / or pyrogallic acid. The reaction composition may further comprise a buffer. The reaction composition may further comprise a halogen salt. The reaction composition may further comprise a surfactant. The reaction composition may further comprise a polyquatemium compound. The surface polymer may be such, wherein each of the first polymerization initiator, the second polymerization initiator, the third polymerization initiator, and the fourth polymerization initiator independently may be selected from 2-bromoisobutyryl bromide (BiBB), p-(chloromethyl)phenyltrimethoxy silane (CPTMS), and chloromethyl (CM) moiety. Each of the first monomer, the second monomer, the third monomer, and the fourth monomer may independently be selected from 2 -hydroxy ethyl methacrylate (HEMA), and glycidyl methacrylate (GMA). The ratio of the first polymerization initiators on the surface of the substrate to nonpolymerizing initiator sites on the surface of the substrate may be controlled within a certain range. Said ratio may be controlled by converting a portion of the first polymerization initiators to nonpolymerizing initiators. Said ratio of first polymerization initiators to non-polymerizing initiator sites on the surface of the substrate may be 1:1, 1:25, 1:40, 1:50, 1:75, 1:100, or 1:200.

[0017] In an aspect, a method for forming a surface polymer of polymer molecules on a substrate is provided, the method comprising providing a substrate, exposing the substrate to a first polymerization initiator, exposing the substrate to a first monomer, exposing the substrate to a second polymerization initiator, and exposing the substrate to second monomer. The method may further comprise exposing the substrate to a third polymerization initiator, and exposing the substrate to a third monomer. The method may further comprise exposing the substrate to a fourth polymerization initiator, and exposing the substrate to a fourth monomer.

[0018] IPTS / 128973811 1In an aspect, a method for forming a surface polymer of polymer molecules on a substrate is provided, the method comprising providing a substrate having first polymerization initiators covalently bound to a surface of the substrate, exposing the substrate to a reaction composition comprising a first monomer to form first polymer molecules covalently bound to first polymerization initiator sites, exposing the substrate to a second polymerization initiator covalently binding to the first polymer molecules, and exposing the substrate to a second monomer to form second polymer molecules covalently bound to the first polymer molecules. The method may further comprise exposing the substrate to third polymerization initiators covalently binding to at least the second polymer molecules, and exposing the substrate to a third monomer to form third polymer molecules from at least the third polymerization initiator sites. The method may further comprise exposing the substrate to fourth polymerization initiators covalently binding to at least the third polymer molecules, and exposing the substrate to a third monomer to form fourth polymer molecules from at least the fourth polymerization initiator sites. By the method, a surface polymer may be provided, wherein the polymer molecules formed on the substrate has an average dry film thickness of at least 0.5 pm. By the method, a surface polymer may be provided, wherein the polymer molecules formed on the substrate has an average dry film thickness of at least 1 pm. In the method, each of the monomer, the second monomer, the third monomer, and the fourth monomer may independently be comprised in a reaction composition comprising a catalyst, a ligand, an activator, and a solvent. The catalyst may be obtained from Cu, Fe or Ru. The ligand may be selected from N.N.N’,N ",A’ ’-pentamethyldiethylene-triamine (PMDETA). tris[2-(dimethylamino)ethyl] amine (MeeTREN), tris(2-aminoethyl)amine (TREN), tris(2-pyridyl-methyl)amine (TPMA), 1,1, 4, 7, 10,10-hexamethyltri ethylenetetramine (HMTETA), tetramethylethylenediamine (TMEDA), 1,4,8,11 -tetramethyl- 1 ,4,8, 11 -tetraazacy clotetradecane (Me4Cyclam), and / or 2, 2?-bipyridyl (BiPy). The activator may be selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose, glucose with GOx, and / or pyrogallic acid. The reaction composition may further comprise a buffer. The reaction composition may further comprise a halogen salt. The reaction composition may further comprise a surfactant. The reaction composition may further comprise a polyquatemium compound. Each of the first polymer molecule, the second polymer molecule, the third polymer molecule, and the fourth polymer molecule may independently be copolymers. Each of the first monomer, the second monomer, the third monomer, and the fourth monomer may independently be selected from 2-hydroxyethyl methacry late (HEMA), glycidyl methacrylate (GMA), n-butyl methacrylate (BuMA), tert-butyl methacrylate (tBMA). benzyl methacrylate (BnzMA), 2-ethylhexyl methacry late (EHMA), 2-hydroxyethyl acrylate (HEA), and IPTS / 128973811 1styrene (St), or a combination thereof. The first monomer may be 2-hydroxyethyl methacrylate (HEMA) or styrene (St). The second monomer may be 2-hydroxyethyl methacrylate (HEMA) and benzyl methacrylate (BnzMA), 2-hydroxyethyl methacrylate (HEMA) and n-butyl methacrylate (BuMA), 2-hydroxyethyl methacrylate (HEMA) and 2-ethylhexyl methacrylate (EHMA), 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxylthyl acrylate (HEA), or 2-hydroxyethyl methacrylate (HEMA) and styrene (St). The ratio of the first polymerization initiators on the surface of the substrate to non-polymerizing initiator sites on the surface of the substrate may be controlled within a certain range. Said ratio may be controlled by converting a portion of the first polymerization initiators to non-polymerizing initiators. Said ratio of first polymerization initiators to non-polymerizing initiator sites on the surface of the substrate may be 1:1, 1:25, 1:40, 1:50, 1:75, 1:100, or 1:200.

[0019] In an aspect, a device structure comprising a substrate and surface polymer is provided, the device structure further comprising a layer of material over the surface polymer, the layer of material being physically and / or chemically bonded to the surface polymer, wherein the material of the layer and the material of the substrate may have different coefficients of thermal expansion. The device structure may be such, wherein the substrate may be a glass substrate and the layer of material may be a metal layer. The device structure may be such, wherein the surface polymer accommodates stress between the glass substrate and the metal layer over a temperature may change of at least 100 Kelvin. The device structure may be such, wherein the surface polymer accommodates stress between the glass substrate and the metal layer over a temperature change of at least 200 Kelvin. The device structure may be such, wherein the polymer accommodates stress between the glass substrate and the metal layer over a temperature change of at least 300 Kelvin. The device structure may be such, wherein the metal layer is a copper layer. The device structure may be such, wherein the surface polymer may have an average dry film thickness of at least 0.5 pm. The device structure may be such, wherein the surface polymer may have an average dry film thickness of at least 1 pm. The device structure may be such, wherein the surface polymer has an average dry film thickness of at least 2 pm. The device structure may be such, wherein the surface polymer has an average dry film thickness of at least 5 pm.

[0020] In an aspect of the disclosure, a system for forming surface polymers is provided, the system comprising a first container containing a reaction composition for forming the first polymer molecules at first polymerization initiator sites on the surface of the substrate, a second container containing chemistry for forming second polymerization initiator sites on the first polymer IPTS / 128973811 1molecules, a third container for forming second polymer molecules on the first polymer molecules at the second polymerization initiator sites, and a substrate displacement device for bringing at least a portion of first polymerization initiator-modified substrate into contact with the reaction composition in the first container for a first controlled time, wherein the controlled time is sufficient for first polymer molecules to be formed on the portion of the polymerization initiator-modified substrate, then for bringing the at least a portion of the substrate into contact with the chemistry in the second container for a second controlled time, wherein the second controlled time is sufficient for second initiator sites to be formed on the first polymer molecules, and then for bringing the at least a portion of the substrate into contact with the reaction composition in the third container for a third controlled time, wherein the third controlled time is sufficient for second polymer molecules to be formed on the second initiator sites on the first polymer molecules, a substrate displacement device for bringing at least a portion of first polymerization initiator-modified substrate into contact with the reaction composition in the first container for a first controlled time, wherein the controlled time is sufficient for first polymer molecules to be formed on the portion of the polymerization initiator-modified substrate, then for bringing the at least a portion of the substrate into contact with the chemistry in the second container for a second controlled time, wherein the second controlled time is sufficient for second initiator sites to be formed on the first polymer molecules, and then for bringing the at least a portion of the substrate into contact with the reaction composition in the third container for a third controlled time, wherein the third controlled time is sufficient for second polymer molecules to be formed on the second initiator sites on the first polymer molecules. The system may be such, wherein one or more of the polymer molecules are copolymers. The system may further comprise at least one container containing chemistry for forming polymerization initiators on a surface of the substrate. The system may further comprise at least one container containing chemistry for rinsing the substrate. The system may further comprise at least one container for drying and / or annealing the substrate. The system may be such, wherein the container for forming polymerization initiators may be a vacuum oven. The system may be such, wherein the container for drying and / or annealing the substrate may be an oven.

[0021] Description of the Drawings

[0022] Certain embodiments of the matter disclosed herein are illustrated in the accompanying drawings. The drawings are, however, in no way intended to limit the scope of the disclosure. In the drawings:

[0023] IPTS / 128973811 1Fig. 1 illustrates the “grafting to” concept schematically.

[0024] Fig. 2 illustrates the “grafting from” concept schematically.

[0025] Fig. 3 schematically illustrates three examples of polymerization initiators, chloromethyl phenyl fragment (left), a 2-bromoisobutyryl fragment (middle), a sulfonyl chloride fragment (right).

[0026] Fig. 4 shows Infrared Reflection Absorption Spectroscopy (IRRAS) spectra of Si PHEMA (spectrum 1) and Si-PHEMA-BiBB (spectrum 2) with peak assignments A: O-H stretching vibration, B: C-H stretching vibration, C: C=O stretching vibration, D: C-H bending vibration, and E: C-0 stretching vibration, see Example 8.

[0027] Fig. 5 shows Infrared Reflection Absorption Spectroscopy (IRRAS) spectra of Si-PHEMA- BiBB-PHEMA (spectrum 1) and Si-PHEMA-BiBB-PHEMA-BiBB (spectrum 2) with peak assignments A: O-H stretching vibration, B: C-H stretching vibration, C: C=O stretching vibration, D: C-H bending vibration, and E: C-0 stretching vibration, see Example 8.

[0028] Fig. 6 shows Infrared Reflection Absorption Spectroscopy (IRRAS) spectra of Si-PHEMA- B1BB-PHEMA-B1BB-PHEMA (spectrum 1), S1-PHEMA-B1BB-PHEMA-B1BB- PHEMA-BiBB (spectrum 2), and Si-PHEMA-BiBB-PHEMA-BiBB-PHEMA-BiBB- PHEMA (spectrum 3) with peak assignments A: O-H stretching vibration, B: C-H stretching vibration. C: C=O stretching vibration, D: C-H bending vibration, and E: C-0 stretching vibration, see Example 8.

[0029] Fig. 7 shows ellipsometry data of the Si-PHEMA-BiBB-PGMA substrate of Example 6. Fig. 8 is a conceptual illustration of substrate (A) with first polymerization initiators (B), followed by formation of first polymer molecules (C), modification with second polymerization initiators (D), and formation of second polymer molecules (E).

[0030] Fig. 9 shows surface polymer thickness as a function of polymerization time for four different molar rations of CPTMS (first polymerization initiator) to TPMS (non-polymerization initiator (“dummy initiator”)) (1:1, 1:50, 1:75 and 1:100) used for attachment to substrate. Fig. 10 shows a schematic cross-sectional representation of a device structure with a film of surface polymer on a substrate, the film of surface polymer acting as a stressaccommodation layer between a substrate and a layer of material deposited on the film of surface polymer.

[0031] Fig. 11 shows a schematic representation of a sy stem for forming films of surface polymer on substrate surfaces.

[0032] IPTS / 128973811 1Fig. 12 shows the nanoindentation regime as carried out in respect of the two substrates with surface polymer films (PHEMA-BiBB-PHEMA and PHEMA-BiBB-PHEA), see Example 18.

[0033] Fig. 13 shows FT-IR spectra of three surface polymers of Example 16 with peak assignments for OH, CH2, and C=O.

[0034] Fig. 14 shows FT-IR spectra of three surface polymers of Example 16 with peak assignments for OH. CH2, and C=O.

[0035] Fig. 15 shows FT-IR spectra of three surface polymers of Example 16 with peak assignments for OH, CH2, and C=O.

[0036] Fig. 16 is an enhancement of the OH and CH2stretching regions of Fig. 16.

[0037] Fig. 17 shows transmission IR overlay ed spectra of Si-PSt, Si-PSt-CM, Si-PSt-P2 and Si-PSt- CM-PHEMA of Example 17.

[0038] Fig. 18 is a plot representing the percentage increase in thickness (second polymer molecule thickness) against BiBB mol% relative to AcBr mol% (thickness profile), see Example 18.

[0039] Fig. 19 shows the force-indentation curves of the surface polymers of Example 18.

[0040] Detailed Description

[0041] The present disclosure relates to the formation of surface polymers from polymerization initiators present on a surface of a substrate. Specifically, the formation of the surface polymers may be accomplished by forming first polymer molecules on a surface of a substrate from first polymerization initiators attached to the surface, and subsequently form second polymer molecules from second polymerization initiators attached to the first polymer molecules.

[0042] Surface polymers within the present context are, thus, polymeric structures having polymer chains that are chemically bonded to a surface at one end. Such polymers can be tailored to provide specific chemical and / or physical properties and can produce precisely tailored chemical structures on a molecular scale.

[0043] Different polymerization techniques have facilitated the specific design and synthesis of surface polymers with strict molecular control and desired properties. In particular, the surface polymers can be viewed as nanoscale “building blocks'’, and due to the flexibility of the surface poly mer chemistry, highly tailored films of surface polymers may be created with respect to chemical composition, thickness, density and architecture.

[0044] IPTS / 128973811 1Several methods for forming surface polymers are known, among them SI-ATRP (surface-initiated atom transfer radical polymerization), SI-RAFT (surface-initiated reversible-addition fragmentation chain transfer), SI-NMP (surface-initiated nitroxide-mediated polymerization), SIPIMP (surface-initiated photoiniferter-mediated polymerization), and SI-A(R)GET (surface-initiated activators (regenerated) by electron transfer) ATRP. A review is given in Chem. Rev.

[0045] 2009. 109. 5437-5527. Other approaches include SET-LRP (single-electron transfer living radical polymerization) and SARA ATRP (supplemental activator and reducing agent atom transfer radical polymerization).

[0046] When forming surface polymers, polymerization initiators are firstly formed on the surface onto which the surface polymers are to be formed. Secondly, the surface is brought into contact with suitable monomers, catalysts, ligands and optionally a solvent, or suitable monomers, catalyst, ligands, a reducing agent and optionally a solvent, whereby the surface polymer can form using certain reaction conditions. The polymerization initiators and the monomers are chosen so as to suit the purposes and properties of the resulting surface polymers. Surface polymers may also be formed as layers of surface polymers by repeating the polymeric architecture, e.g., using another starting monomer (block copolymers).

[0047] Among these known procedures for formation of surface polymers, (ARGET) ATRP and SET-LRP are widely used. For the polymerizing chains to propagate, a monomer, a catalyst, a ligand and a solvent are needed. In (ARGET) ATRP and SET-LRP polymerizations, some reactions activate the catalyst, thereby, promoting polymerization, and at the same time, other reactions deactivate the catalyst to impede polymerization. SARA-ATRP and SET-LRP is described, e.g., in https: / / www.cmu.edu / maty / atrp-how / procedures-for-initiation-of-ATRP / SARA-ATRP-or-SET-LRP.html.

[0048] Both the SET-LRP and (ARGET) ATRP method rely on the formation of a complex between the ligand and ahalide formed with a transition metal as specified in the Periodic Table (usually CuCh or CuBn in the case of ARGET ATRP, and Cu(0) in the case of SET-LRP.

[0049] The ARGET ATRP involves a halogen transfer between a halogen capped species, Pn-X and Cu(I)X / L catalyst, resulting in the formation of a propagating radical (Pnradical) and Cu(II)X2. The propagating radical undergoes polymerization with monomers, forming the growing polymer IPTS / 128973811 1chain. Controlling the ratio between Cu(I)X / L and Cu(II)X2 / L allows control of the polymerization itself. This is well-known for these types of polymerizations.

[0050] From WO 2019 / 196999 Al, which is incorporated by reference in its entirety, as if fully set forth herein, an alternative oxygen-tolerant method for forming surface polymers is disclosed. The catalyst / ligand complex described in WO 2019 / 196999 Al is halogen free in so far as the catalyst / ligand complex formed is not complexed with a halogen anion. An advantage is that the complex formed between the transition metal and the ligand is inactive (i.e., not available for initiating polymerization of the monomer) and stable (oxygen-insensitive), but the system can be activated “on demand’', thus, initiating polymerization and propagation of the surface polymers.

[0051] The present disclosure relates to a substrate having surface polymers formed on a surface of a substrate, the surface polymer comprising first polymer molecules covalently bonded to first polymerization initiation sites on the surface of the substrate, and second polymer molecules covalently bonded to second polymerization initiation sites on the first polymer molecule.

[0052] Within the present context, the terms “a surface of a substrate” or “a substrate surface” are intended to mean all available surfaces or a portion or portions of the available surfaces. For specific purposes, surface polymers may be formed only on a portion of a given surface.

[0053] In one aspect, the surface polymer is such, wherein the average dry film thickness of the surface polymer is at least 0.5 pm.

[0054] In another aspect, the surface polymer is such, wherein the first polymer molecules, the second polymer molecules, or the first polymer molecules and the second polymer molecules are copolymers.

[0055] The inventors have surprisingly found that providing a surface polymer structure of two polymeric molecules make possible the design of complex structures, optionally modulating surface polymer properties, and make possible the specific design of relatively “thick” surface polymers, and of surface polymers with different properties.

[0056] Modulation of thickness of surface polymers may not be an easily achievable task. With the methods and surface polymers composed of at least two polymer molecules, such modulation may IPTS / 128973811 1indeed be possible. Surface polymers composed of polymer molecules, wherein at least one of the polymer molecules is a copolymer make possible the preparation of even more complex structures.

[0057] The inventors have surprisingly found that surface polymers having an average dry film thickness of at least 0.5 pm may be obtained. When one end of long polymer molecules is tethered to a substrate or any interface, the other end gets stretched due to repulsion originating from volumeexpulsion effects among the neighboring polymer chains. The extent of stretching depends on the “grafting density” (o) or the number of grafted polymer molecules per unit area. Such densely grafted surface polymer composed of polymer molecules may be referred to as “Polymer Brushes” owing to their structural similarity with brushes where one can imagine the tethered polymer molecules as the bristles on the brush (the substrate). The overall thickness of the surface polymer composed of polymer molecules is expected to show a linear dependence on the density (a). and the number average molecular weight (Mn) of the tethered polymer molecules, which may be expressed by the following equation (I):

[0058] Thickness (h) = o Mn / p NA (I)

[0059] where a is the grafting density of the surface attached polymer molecules Mnis the molecular weight by number average of the polymer, p is the bulk density of the polymer, and NA is Avogadro’s number. In general, the maximum grafting density (o) that can be achieved by surface-initiated controlled radical polymerization (SI-CRP) lies between 0.3 to 0.4 irrespective of a very high polymerization initiator density on the surface (see Adv. Polym. Sci. (2006) 197: 1-45). Plausible reasons could be inefficient initiation due to lack of access in such a constricted environment, and undesired termination of the radicals soon after initiation due to proximity. Therefore, the known methods relies solely on the ultimate success of extending each polymer chain to an ultra-high molecular w eight extended length. However, there has been only limited success in growing ultra-high molecular weight surface polymer bound polymeric chains using the controlled radical polymerization (CRP) approach. To aid the growth (monomeric propagation) of ultra-high molecular weight surface bound polymers, it has been attempted to slow down the polymerization kinetics to eliminate undesired chain-termination and transfer, however, this approach requires an extremely inert reaction environment, and this approach has not. to the inventors’ knowledge, been applied successful to providing surface polymers with a

[0060] IPTS / 128973811 1thickness above 0.5 pm. The attempted processes, even if functional, have a limited potential in being successful for in a high-volume manufacturing process (HVM).

[0061] Within the present context, the term “surface polymer’’ is intended to mean the combination of the first polymer molecules and further polymer molecules, said further polymer molecules propagated by monomeric units from subsequent polymerization initiators bonded to polymer molecules rather than polymerization initiators bonded to the surface of the substrate. Complex, branched surface polymer architectures may, thus, be formed following several polymerization events. Some of the polymerization events may comprise forming copolymers. The first polymer molecules may be composed of copolymers. The second polymer molecules may be composed of copolymers. The first polymer molecules and the second polymer molecules may be composed of copolymers.

[0062] In accordance herewith the surface polymer may further comprise third polymer molecules covalently bonded to at least third polymerization initiator sites on the second polymer molecules. In accordance herewith, the third polymer molecules are bonded covalently to some first polymerization initiator sites and / or some second polymerization initiator sites.

[0063] The surface polymer may further comprise fourth polymer molecules covalently bonded to at least fourth polymerization initiator sites on the third polymer molecules. In accordance herewith, the third polymer molecules may be bonded covalently to some first polymerization sites, some second polymerization initiator sites, and / or some third polymerization sites.

[0064] The surface polymer may further comprise further polymer molecules, e.g., fifth, sixth and so on polymer molecules. Such further polymer molecules may be propagated from further polymerization initiators attached covalently to the preceding polymer molecules. Thus, attachment of a fifth polymerization initiator makes possible attachment of a fifth polymer molecule, and so on. Third, fourth, fifth, etc., polymer molecules may be composed of copolymers.

[0065] The average dry film thickness of the surface polymer may be at least 0.5 pm. The average dry film thickness of the surface polymer may be at least 1 pm. The average dry film thickness may be at least 2 pm. The average dry film thickness may be at least 3 pm, at least 5 pm, or at least 8 pm.

[0066] IPTS / 128973811 1In general, three types of surface polymer "coatings" are known, namely:

[0067] 1) Preformed polymers which are deposited onto a substrate either as a polymer melt by e.g. a molding process, by doctor blading, die slot coating or spin coating a dilute solution of the polymer in a suitable solvent. No covalent bonds are formed between the polymer and the surface in this methodology’, barring the presence of specific reactive groups on both the substrate surface and the polymer itself. In the case that such reactive groups are present on both polymer and substrate surface, the polymer is “grafted to”, which is described further below.

[0068] 2) “Grafting to” is a method of attaching a polymer chain to a surface. The polymer chains are covalently attached to the surface at one chain-end. The method is known to the person skilled in the art, to comprise pre-formed polymers in solution, said polymers having a reactive chain-end group. In solution, these polymers are not yet surface-attached. The reactive end group can react with a suitable reactive group on the surface in question. Typically, the reactive group is deposited or in another way pre-formed on the surface. The pre-formed polymer is brought into solution, where the conformation of the individual polymer chains is subject to solvent interactions and energetics. Generally, the chains will adopt some version of the coiled coil to maximize entropy. This conformation is retained when the reactive chain-ends react with the reactive groups on the surface. The area occupied by grafting this polymer coil to the surface is generally much larger than the area occupied by the reactive surface group, and, thus, neighboring reactive surface groups are blocked for reaction by the polymer coil. A much higher polymer grafting density could theoretically be obtained if a chain was grafted to the surface in a stretched, linear conformation. Such a conformation is, however, not achievable for polymers in solution given the entropically favored coiled coil conformation which the chains will adopt in solution unless extended chain conformation is stabilized with highly solvating, or strongly binding molecules of solvent in diluted solutions, or via charge repulsion of neighboring units of polymer chains in polyelectrolytes under certain pH conditions. The straight and linear polymer conformation is highly unfavored by entropy and is thus not generally observed for polymers in solution. How ever, a surface polymer coating consisting of polymer chains with a more linear conformation, attached to the surface with a much higher density can be obtained using the “grafting from” methodology- described below.

[0069] 3) In the “Grafting From” method, the surface which is to be modified with a surface polymer is firstly modified with molecules containing a polymerization initiator. Polymerization initiators are covalently attached. Following polymerization initiator modification / deposition, polymer chains are grown from these surface anchored initiators by extension of the polymer chain by IPTS / 128973811 1reaction of monomeric units. The conformation of these polymers is governed by entropy as described above, but also by the fact that the high density of initiators on the surface means that each formed polymer chain will interact with its neighboring chains, giving rise to steric repulsion. As such, the conformation of these chains becomes a balancing act between entropy, which favors the random coil, and the steric constraints imposed by the high density of the polymer chains, forcing the chains to stretch away from the surface to occupy as little space as possible. The result is that polymer chains stretch away from the surface to reduce steric interactions, despite this conformation being of a lower entropy than e.g. the coiled coil. Polymer chains anchored covalently to the surface at one end, and confined to the stretched conformation are considered a special type of surface polymers, namely “polymer brushes’". Polymer brushes can only be formed by the “grafting from” approach which circumvents the low grafting density’ obtained by the "‘grafting to”-approach described above.

[0070] The surface polymer as formed herein is formed using the “grafting from” approach. A surface polymer formed on a surface of a substrate may possess specific properties obtained through propagation of different monomeric units, thus, obtaining complex architectures of the resulting surface polymer formed of polymer molecules.

[0071] It is to be understood that by the term “thickness of a surface polymer"’ or “thickness of a polymer on a surface” is meant the film formed on the substrate, i.e., the surface polymer as defined herein. The thickness is often measured as the dry film thickness by ellipsometry but may be measured by other means such as reflectometry or by measuring a step edge in the coating by atomic force microscopy (AFM) or profilometry. Generally speaking, a substrate with a surface polymer film is considered dry when no visible solvent film, droplets, or residues are observed on the surface of the substrate. Measurements such as atomic force microscopy (AFM) and profilometry demand that a step edge is made in the coating from the outer edge of the coating and all the way to the surface of the substrate, by e.g. scratching. Thus, a targeted surface polymer thickness may be obtained within the applied predefined polymerization time. In the dry state, the surface-tethered polymer molecules acquire a conformation between fully collapsed and stretched conformation where the degree of stretching depends on the grafting density. When a second polymerization is commenced from the polymer-bound-initiators, the tethered polymer molecules start acquiring a more stretched conformation with the increasing length of the sidechains.

[0072] IPTS / 128973811 1The achievable thickness of the surface polymer may be influenced by several factors, e.g., availability and density of polymerization initiators on the substrate and / or on formed polymer molecules, the monomer for surface polymer formation and reaction conditions such as the rate and kinetic profile of surface polymer formation.

[0073] The average dry film thickness may depend on the density (anchoring points per area) of end bonded polymer molecules (chains) (polymer molecules bonded to the substrate, i.e., first polymer molecules) and the length of the individual polymer molecules. When assessing the thickness, only the density of grafted polymer molecules should be considered, i.e., the grafting density of attached polymerization initiators is not decisive, rather the density of surface polymerization initiators which initiate polymerization is the relevant grafting density, and this is the grafting density mentioned in the equation (I) above. It is to be understood that “initiator” in singular may also cover a plurality of a single type of initiator as a single initiator will be a plurality of the chemical entity .

[0074] Controlling the grafting density of the first polymerization initiator may contribute to obtaining thicker surface polymers and / or more complex surface polymer structures, the inventors hypothesize. In the Examples, the inventors have shown that a second polymerization event from second polymerization initiators bound to the first polymer molecule may result in a major increase in the thickness of the combined surface polymer. The inventors believe that controlling the grafting density of at least the first polymerization initiator may create more space around each formed polymer molecule on the substrate (first polymer molecule), as well as enable formation of longer first polymer molecules (longer individual surface polymer chains, resulting in a higher average dry’ film thickness). More space around each first polymer molecule may provide more free volume being beneficial in the second polymerization, and longer first polymer molecules may enable the first polymer molecules to extend further from the surface when the second polymer molecules increase steric interactions at the surface and, thus, resulting in a thicker surface polymer.

[0075] In accordance herewith, the grafting density of the first polymerization initiators may be controlled, e.g., a ratio of the first polymerization initiators on the surface of the substrate to certain non-polymerizing initiators (“dummy initiators”) on the surface of the substrate may be controlled within a certain range. One way of controlling the grafting density is to firstly’ deposit first polymerization initiator molecules at the highest possible density (no restrictions in deposition on IPTS / 128973811 1the substrate), followed by conversion of a fraction of the first polymerization initiators into nonpolymerization initiators. Such conversions can be carried out through chemical reactions or by¬ exposure to UV light of wavelength and intensity sufficient to break the C-halide bond of the polymerization initiator, rendering it incapable of initiating polymerization reactions. Another path to controlling the ratio of polymerization initiators to non-polymerization initiators entails exposing a cleaned substrate to a mixture of polymerization initiators and non-polymerization initiators. The ratio of polymerization initiators to non-polymerizing initiators on the surface may depend on, but not necessarily be equal to, the ratio of polymerizing initiators and nonpolymerizing initiators in the initiator grafting composition. The surface ratio of the two will depend both on the ratio of the two molecules in the initiator grafting solution, as well as their relative reactivities. By way of example, the ratio of first polymerization initiators to nonpolymerizing initiator sites on the surface ofthe substrate may, e. g., be 1:1, 1:25, 1:40, 1:50, 1:75, 1:100, or 1:200. Beyond controlling the grafting density of first initiator molecules to the surface of the substrate, it is furthermore possible to control the grafting density- of the second, third, and so on, polymerization initiators attached to the first, second, and so on, polymer molecules. The approach here is quite comparable to the methods listed for controlling grafting density of polymerization initiators on the surface of the substrate. In the case of poly(2-hydroxyethyl methacry late) (HEMA) monomer, the grafting density- of initiators on the polymer molecule can be controlled by adding a ratio of polymerization initiator (2-bromoisobutyryl bromide) (BiBB) and non-polymerization initiator or “dummy initiator" such as acetyl bromide (AcBr), pivaloyl bromide or isobutyryl bromide, but no ability to initiate the polymerization.

[0076] Attachment of polymerization initiators to a surface of a substrate (first polymerization initiator) may be performed by various procedures. Polymerization initiators are covalently bonded to the surface of the material, see, e.g., WO 2014 / 0075695. The first polymerization initiators may be provided with a predefined surface chemistry- to enable attachment onto the surface of the substrate, depending on the nature of the substrate. Non-limiting examples of suitable chemistries for attaching polymerization initiators on surfaces include but are not limited to aryl diazonium salts, organosilanes. organothiols, organophosphonic acids, organophosphonates, catechols, iodonium salts, alkenes, alkynes, and sol-gel coatings. Surface anchored first polymerization initiators can be prepared as multilayer films or monolayer films. Monolayer films can be densely-packed (full monolayer coverage) or partly packed, covering all or only a part of the available surface. The density of the first polymerization initiator influences the density of the subsequently-formed surface polymer. Density of initiators would be understood by persons of ordinary skill as IPTS / 128973811 1the number of first polymerization initiators per unit area of the substrate.

[0077] The attachment of first polymerization initiators usually follows a 1-step or a 2-step process. The 1-step process applies grafting of benzyl halide (like benzyl chloride) or secondary or tertiary halide moieties onto the surface of the substrate either by diazonium or silane grafting. The benzyl halide and secondary and tertiary halide moiety act as the first polymerization initiator for the following surface-initiated polymerization. The 2-step process usually applies surface grafting of an initial organic compound with a nucleophilic group, and in a second step using the nucleophilic group to attach an initiator moiety. The nucleophilic group may include a hydroxyl or amine group. Then, the nucleophilic group may be reacted with an electrophile to add an initiator moiety, forming a covalent bond between the two. The initiator moiety may be. e.g., benzyl halide and tertiary halide moieties.

[0078] The attachment process is further described below. The procedures may in general apply to all types of substrates.

[0079] Silane grafting 1-step:

[0080] Initiators can be attached to a surface in one step by silane grafting of trialkoxy silane with benzy l halide or tertiary halide groups. The silane grafting is normally done either by vapor deposition, in solution, by spray coating, or paint-on coating.

[0081] Diazonium grafting 1-step:

[0082] Initiators can be attached to a surface in one step by grafting aryl diazonium salts with benzyl halide groups. The diazonium grafting is normally done either by activating the aryl diazonium salt electrochemically or chemically or by letting it react spontaneously. Diazonium salts can be pre-synthesized before being used for grafting reaction or formed in-situ during grafting reaction from a set of precursors added to the grafting reaction solution.

[0083] Diazonium grafting 2-step:

[0084] Another route of initiator attachment is by7a two-step process. The first step being grafting of an aryl diazonium salt that contains a nucleophilic group (alcohol or amine). In a second step a nucleophilic acyl substitution reaction adds a halogen containing group, giving the attached polymerization initiator.

[0085] IPTS / 128973811 1Silane grafting 2-step:

[0086] The first step being grafting of a silane that contains a nucleophilic group (alcohol or amine). In a second step, a nucleophilic acyl substitution reaction adds a halogen containing group, giving the attached polymerization initiator.

[0087] Other processes for attaching first polymerization initiators may be applied. E.g., the polymerization initiator CPTMS may be attached using a vapor deposition method or a dipping method.

[0088] If only specific areas of a material surface are to be coated with first polymerization initiators, the area(s) with functional polymerization sites may be blocked, e.g., chemically or by using a foil, seal or cover, or etched, or masked, protected, or defined by lithographic patterning.

[0089] In particular, the first polymerization initiator may be selected from CPTMS, the second polymerization initiator may be selected from BiBB, CPTMS or chloromethyl (CM) moiety, the third polymerization initiator may be selected from BiBB or CPTMS, the fourth polymerization initiator may be selected from BiBB, CPTMS, or CM moiety, and the fifth polymerization initiator may be selected from BiBB, CPTMS or CM moiety, and so on.

[0090] The surface polymer formed on a surface of a substrate may be composed of several types of polymer molecules composed of several types of monomeric units. Suitable examples of monomers are indicated below. The monomers chosen may be any such desire for the final product. It is to be understood that the below-mentioned monomers may be applicable both in the case of the formation of the first polymer molecules as well as any subsequent polymer molecules (second, third, fourth, fifth, sixth, etc.), although certain limitations exist for monomers selected for further functionalization with subsequent polymerization initiators. Such limitations include the need for reactivity compatibility7between the surface polymer molecules and the reactive part of subsequent polymerization initiator molecules which are responsible for forming chemical bonds to the surface polymer molecules, or chemical modification of functional groups present on the surface polymer to convert that functional group into a polymerization initiator.

[0091] Specifically, if the surface polymer molecules have nucleophilic moieties such as, but not limited to, hydroxyl, amine, thiol, and phenyl groups, the reactive moiety on the polymerization initiator

[0092] IPTS / 128973811 1molecule which is to react with the surface polymer, should be an electrophile, such as but not limited to epoxide, acid chloride, acid bromide, and alkyl halide.

[0093] If the surface polymer molecule has electrophilic groups such as acid chlorides, acid bromides, or oxirane (epoxide) groups, the corresponding reactive part of the polymerization initiator molecule responsible for the bond formation between surface polymer and polymerization initiator should be nucleophilic, such as, but not limited to, amine, hydroxy, thiol, and thiolate.

[0094] Finally, if the surface polymer molecules cannot clearly be considered either electrophilic or nucleophilic, the surface polymer molecules should be able to undergo chemical reactions and conversions to become either nucleophilic or electrophilic, to accommodate functionalization with subsequent polymerization initiators with suitable reactivities.

[0095] Non-limiting examples of suitable nucleophilic functional groups on the polymer molecules, include but are not limited to amines, hydroxyl groups, carboxylic acids, carboxylates, thiols, thiolates, and phenyls.

[0096] Non-limiting examples of electrophilic functional groups on the polymer molecules include, but are not limited to. epoxides, pentafluorophenyl esters, and N-hydroxysuccinimide activated esters.

[0097] Non-limiting examples of polymer molecules that are considered nucleophilic include but are not limited to, poly(2-hydroxyethyl methacrylate), poly(2-amineethyl methacrylate), poly-(methacrylic acid), and poly (styrene).

[0098] Non-limiting examples of polymer molecules that are considered electrophilic include but are not limited to poly(glycidyl methacrylate), poly(pentafluorophenyl methacrylate), and N-hydroxysuccinimide (NHS)-activated esters such as polyOV-hydroxysuccinimide 4-vinylbenzoate).

[0099] Non-limiting examples of polymer molecule functional groups that are not nucleophilic, but can be converted into nucleophilic functional groups, include but are not limited to epoxides, N-boc amines, and silyl ether protected alcohols such as RO-trimethylsilyl ether (RO-TMS).

[0100] Examples of such polymer molecules and the conversion they can undergo to become nucleophilic include but are not limited to poly(glycidyl methacrylate) which is not considered nucleophilic. IPTS / 128973811 1but can be exposed to reaction conditions such as acid hydrolysis which results in epoxide ringopening reaction and production of hydroxyl groups on the polymer molecule, which can act as nucleophiles for the introduction of subsequent polymerization initiators. Another example includes poly(2-(N-tert-butoxycarbonylamino)ethyl methacrylate) which contains a tert-butyl carbamate group which may be converted to a reactive and nucleophilic amine by acid catalysis. As such, the poly(2-(N-tert-butoxycarbonylamino)ethyl methacrylate) is not nucleophilic and may be less suited for introduction of subsequent polymerization initiator, but after the removal of the protection group and revealing the amine, the polymer molecule becomes well suited for introduction of polymerization initiator.

[0101] Non-limiting examples of polymer molecule functional groups which are not electrophilic, but can be converted into electrophilic groups, include but are not limited to poly(methacrylic acid) which upon reaction with a chlorinating substance such as thionyl chloride may be converted to an electrophilic poly (methacryloyl chloride), and poly(2-hydroxyethyl methacrylate) which upon reaction with p- toluene sulfonyl chloride forms poly(2-(tosyloxy)ethyl methaciylale). In this case, the tosyl group makes for a reactive electrophile for reaction with a nucleophilic moiety.

[0102] A final class of monomers suited for the introduction of subsequent polymerization initiators include monomers which may be converted directly into a polymerization initiator, such as but are not limited to poly(sodium 4-vinylbenzenesulfonate) which upon reaction with a chlorinating substance such as thionyl chloride will be converted into poly(4-vinylbenzenesulfonyl chloride), from which polymerization may be initiated, and poly(3-sulfopropyl methacrylate) potassium salt which upon reaction with a chlorinating substance such as thionyl chloride will be converted into poly(3-(chlorosulfonyl)propyl methacrylate), from which polymerization may be initiated.

[0103] The monomers listed below may all be suitable for forming the second, third, fourth, fifth, and so on polymer molecules, and of the monomers listed below, those that fulfil the above requirement of having nucleophilic moieties or functional groups that can be converted to nucleophilic groups, or having electrophilic groups or functional groups that can be converted to electrophilic groups, or having functional groups which can be directly converted into polymerization initiators are also suitable for subsequent introduction of the second, third, fourth, fifth, and so on, polymerization initiators.

[0104] IPTS / 128973811 1Thus, non-limiting examples of appropriate monomer types include anionic, cationic, zwitterionic, protic and aprotic monomers, and include acrylates, methacrylates, halogensubstituted alkenes, acrylamides, methacrylamides, and styrenes, as well as mixtures thereof. The generic monomer structure comprises a polymerizable part (a vinyl group), which in certain embodiments is connected to a functional group responsible for the specific functionality (e.g., adhesion, permeability, electric and ionic conductivities) of the certain monomer through a certain linker chemistry.

[0105] For acrylate monomers, non-limiting examples of functional moieties include but are not limited to alkyl groups, ary l groups, sulfonates, fluorosulfonates, carboxyls, metal carboxylates, ethers, poly(ether) groups, bis(sulfonyl)amides. fluorinated sulfonates, perfluoroalkyl carboxylate, borate, fluorinated borate, borate ester derivatives, bis(trifluoromethane)sulfonimide, triflimides and derivatives thereof, halogenated alkyl chains, and mono-, di-, and tri-alkoxy silanes.

[0106] The polymerizable part and the functional part of monomer can. in certain embodiments, be connected by a linker moiety. Non-limiting examples of appropriate linker chemistries include but are not limited to alkyl chain, esters, ethers, poly(ethers), amines, amides, ary ls, and any combination(s) thereof. Non-limiting examples of appropriate acry late monomers containing alkyl linkers include but are not limited to methyl acry late, ethyl acry late, and lauryl acrylate. Non-limiting examples of monomers using ether and poly(ether) linker chemistry include but are not limited to poly(ethylene glycol) methyl ether acrylate, and poly(ethylene glycol) acrylate. Non-limiting examples of monomers without linker chemistry include but are not limited to acry lic acid, and lithium acrylate, sodium acrylate, and vinyl imidazole.

[0107] For methacrylate monomers, non-limiting examples of appropriate functional moieties include but are not limited to carboxylic acids, metal carboxylates, esters, alkyl alcohols, oxiranes (epoxides), linear and branched alkyl groups, alkenes, ary l groups, sulfonates, fluorosulfonates, bis(sulfonyl)amides, fluorinated sulfonates, perfluoroalkyl carboxylate, borate, fluorinated borate, borate ester derivatives. bis(trifluoromethane)sulfonimide. triflimides. and derivatives thereof, halogenated alkyl chains, and mono, di, and tri-alkoxy silanes.

[0108] Non-limiting examples of linker chemistries include but are not limited to alkyl chains, esters, ethers, poly(ethers. amines, amides, aryls, and any combination(s) thereof.

[0109] IPTS / 128973811 1Non-limiting examples of methacrylate monomers include but are not limited to methacrylic acid, lithium methacrylate, sodium methacrylate, methyl methacrylate (MMA, potassium 3-sulfpropyl methacrylate (K-SPMA, 2-hydroxyethylmethacrylate (HEMA, glycidyl methacrylate (GMA, ethyl meth acryl ate, n-butyl methacrylate (BuMA, tert-butyl methacrylate (tBMA, lauryl methacrylate, (((perfluorobutyl)sulfonyl)oxy)methyl methacrylate, 3-(N-((trifluoromethyl)sulf-onyl)sulfamoyl)propyl methacrylate, I A.177,277,227-heptadecafluorodecyl methacrylate (HFDMA, allyl methacrylate, 2-(( tri ethoxy silyl)oxy)ethyl methacrylate, and 2-(3-(triethoxy-silyl)propyl)ethyl methacrylate.

[0110] Non-limiting examples of acrylate monomers include but are not limited to methyl acrylate (MA), tert-butyl acrylate (tBA). lauryl acrylate (LA), and 2-hydroxyethylacrylate (HEA).

[0111] Non-limiting examples of appropriate halogen-substituted alkene monomers include but are not limited to vinyl chloride, vinylidene difluoride, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene.

[0112] Non-limiting examples of appropriate acrylamide monomers include but are not limited to acry lamide, A-Ao-propylacrylamide, A-tert-butylacrylamide, and A-hydroxy ethyl acry lamide.

[0113] Non-limiting examples of appropriate methacrylamide monomers include but are not limited to A-teo-propylmethacrylamide, methacrylamide, A-terEbutylmethacrylamide, and A-hydroxy ethyl methacrylamide.

[0114] Non-limiting examples of appropriate styrene monomers include but are not limited to styrene, 4-methylstyrene, 2,3,4,5,6-pentafluorostyrene, / J-divinylbenzene, 4-chlorostyrene, sodium 4-vinylbenzenesulfonate, lithium 4-vinylbenzenesulfonate, and 4-vinylphenyl 1, 1,2, 2, 3, 3, 4,4,4-nonafluorobutane- 1 -sulfonate.

[0115] Monomer(s) may be chosen to provide compatibility / adhesion / elasticity. as appropriate for a specific application. Monomer(s) can also be selected to enhance or diminish electrical and / or ionic conductivity7, and / or permeability7. Monomers may be chosen to improve interface stability of a surface in question. Monomers may suitably be used in an amount corresponding to a percentage of the total volume of the reaction medium. For example, a liquid monomer may constitute e.g. 0.5 vol%, 2 vol%, or 10 vol% of areaction medium. In each application, an amount IPTS / 128973811 1of monomer may be chosen to obtain desired polymerization kinetics, solubility of the monomer, and cost of the monomer The range for the amount of monomer will in most cases be 0.5 vol% to 50 vol%.

[0116] Following formation of the polymer molecule, the formed polymer molecule is indicated with a “P” as prefix to the monomer. By way of example, methyl methacrylate monomer is denoted MMA, and after polymerization, the polymer molecule is denoted PMMA. Likewise. 2-hydroxy-ethyl methacrylate is denoted HEMA, and after polymerization, the polymer molecule is denoted PHEMA.

[0117] Each of the first polymer molecule, the second polymer molecule, the third polymer molecule, and the fourth polymer molecule may independently be selected from poly(2-hydroxyethyl methacrylate) (PHEMA), and poly(glycidyl methacrylate) (PGMA), poly(n-butyl methacrylate) (PBuMA), poly(tert-butyl methacrylate) (PtBMA), poly(benzyl methacrylate) (PBnzMA), poly(2-ethylhexyl methacrylate) (PEHMA), poly(2-hydroxylethyl acrylate) (PHEA), and polystyrene (PSt), or a combination thereof.

[0118] The first polymer molecule may suitably be chosen from PHEMA, or PGMA. The second polymer molecule may suitably be chosen from PMMA, PHEMA, PGMA, and PtBMA. The third polymer molecule may suitably be chosen from PMMA, PHEMA, PGMA, and PtBMA. The fourth polymer molecule may suitably be chosen from PMMA, PHEMA, PGMA, and PtBMA. The fifth polymer molecule may suitably be chosen from PMMA, PHEMA, PGMA, and PtBMA.

[0119] The first polymer molecule may be poly(2-hydroxy ethyl methacrylate) (PHEMA) or polystyrene (PSt). The second polymer molecule may be a copolymer of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(benzyl methaciy late) (PBnzMA), poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(n-butyl methacrylate) (PBuMA), poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-ethylhexyl methacrylate) (PEHMA), poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl acrylate (PHEA), or poly(2-hydroxyethyl methacrylate) (PHEMA) and polystyrene (PSt).

[0120] Examples of surface polymers include PHEMA-BiBB-PMMA, PHEMA-BiBB-PHEMA, PHEMA-BiBB-PGMA, PGMA-(OH)-(BiBB)-PMMA. PGMA-(OH)-(BiBB)-PHEMA, PHEMA-BiBB-PHEMA-BiBB-PHEMA, PHEMA-BiBB-PHEMA-BiBB-PHEMA-BiBB- IPTS / 128973811 1PHEMA, PHEMA-BiBB-PHEMA-BiBB-PHEMA-BiBB-PHEMA-BiBB-PHEMA. PHEMA-BiBB-(HEMA-co-PBnzMA), PHEMA-BiBB-(HEMA-co-PBuMA), PHEMA-BiBB-(PHEMA-co-PEHMA), PHEMA-BiBB-(PHEMA-co-PHEA), PHEMA-BiBB-(PHEMA-co-PSt), and PSt-CM-PHEMA. By way of example, PHEMA-BiBB-PMMA denotes that the first polymer molecule is PHEMA, the second polymerization initiator is BiBB, and the second polymer molecule is PMAA.

[0121] As mentioned above, the present disclosure relates to surface polymers comprising copolymers.

[0122] Within the present context, the expression “copolymer’ or “copolymers” is intended to mean a polymer molecule of the surface polymer as defined herein comprising at least two different monomeric repeat units. Copolymers may be formed by copolymerizing different types of monomers or by subsequent partial chemical modification of a homopolymer (within the polymer molecule) to add a chemical modification of one ty pe of monomeric repeat unit to obtain a different type of monomeric repeat unit.

[0123] When more than one type of monomer is polymerized simultaneously, the polymerization can result in statistical, alternating, and in some special cases block copolymers depending on the relative reactivity ratio of the monomers. The reactivity ratio of a monomer in copolymerization is defined by the ratio of the rate at which a monomer adds to a growing chain of its own type versus the rate at which it adds to a growing chain comprised of the other monomer. For statistical copolymers, the distribution of the different types of monomeric repeat units may follow different statistical laws such as Bemoullian (zero-order Markov), first- or second-order Markov depending on the polymerization method and the reactant composition. “Random copolymer” is the most common terminology used to describe statistical copolymers irrespective of the type of distribution.

[0124] The structures of statistical / random copolymers and alternating copolymers can be symbolized as follows (— ABAABABBAABAAABBBA— ) (— ABABABABABAB— ), wherein A and B represent two different type of monomeric repeat units. The structure of block copolymers is represented by two or more homopolymer blocks of different monoeric repeat units, connected by covalent linkages, and may be represented by AmBn(AB diblock), AmBnAm (ABA triblock), (AmBn)p (AB multiblock), AmBnCP(ABC triblock) and so on. While statistical / random copolymers that are, in general, prepared by simultaneous copolymerization of more than one IPTS / 128973811 1monomer, block copolymers are, in general, prepared by sequential polymerization of different types of monomers. Thus, a considerable structural variability is possible for block copolymers due to the additional variability such as the number of blocks and the block lengths (m, n etc.). Alternating, statistical and random copolymers are designated as poly(A-alt-B), poly(A-stat-B), poly(A-ran-B) / poly(A-r-B), wherein A and B represent two different ty pes of repeat units. In the present disclosure, we followed the recent literature trends and therefore any polymer that has been prepared by’ simultaneous copolymerization of more than one monomer will be called as random copolymer, symbolized as poly(A-ran-B). Block copolymers are designated as poly(polyA-block-polyB) / poly(polyA-b-polyB). As mentioned above, these different types of copolymers may be denoted “co”, e.g. poly(polyA-co-polyB) in the absence of a more specific destinction. In the above, a prefix “P” may replace the term “poly”.

[0125] The copolymers may be block-copolymers, random copolymers, or binary’ mixed polymers, where two or more separate monomers are used to propagate the surface polymer for different surface polymer architectures. Herein, the term “copolymer” is intended to include block copolymers, random copolymers, and binary mixed polymers (e.g., “PHEMA-co-PHEA” being a copolymer of PHEMA and PHEA). Sometimes, “r” may be used to denote random copolymers (e.g., “PHEMA-r-PHEA” being a random copolymer of PHEMA and PHEA). Sometimes “b” may be used to denote a block of one polymer and a block of another polymer (e.g., “PHEMA-b-PHEA” being a first block polymer of PHEMA, and a second block of PHEA).

[0126] A surface polymer having repeat units of different monomers may contribute to different properties resulting in a surface polymer with a combination of desired properties. The copolymers may be part of any of the surface polymer molecules alone or in combination, e.g., the first surface polymer molecule, the second polymer molecule, or the third polymer molecule. The copolymer may be introduced by repeating certain of the steps for forming surface polymers to build up block copolymers from viable chain ends of the surface polymer. Copolymers may also be formed by applying a combination of two or more different monomers, in various ratios, for a surface polymerization event.

[0127] Hence, two or more functional groups (e.g., halogen atoms, hydroxyl groups, or amine groups) can be incorporated, resulting in surface polymers with a unique set of combined properties, each of which is inherent from individual monomers. Thus, copolymerization is a powerful tool to modulate surface polymer properties by combining the properties of two or more monomers. The IPTS / 128973811 1resulting copolymer may exhibit properties that cannot be achieved by polymerization of a single monomer. A handle for modulating the properties may be by varying the incorporation of the comonomers, e.g., by varying the initial ratios of the co-monomers.

[0128] It is expected that a wide range of different substrates will be useful in connection with the disclosure herein, however, suited substrates should provide a surface, allowing firstly attachment of first polymerization initiators, and secondly formation of surface polymers of first polymer molecules from said first polymerization initiator sites. Substrates may wholly or partly be composed of metal (like aluminum, steel, nickel, gold, silver, platinum, chrome, copper, iron and alloys), glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composite materials, plastics, polymer materials, semiconductors, compound semiconductors (e.g., gallium arsenide (GaAs), gallium nitride (GaN), germanium sulfide (GeS), and indium phosphide (InP)), and particles (e.g., Si, metal, metal alloys and coated particles). Substrates may be patterned or unpattemed. If patterned, substrate surface(s) may comprise one or more of the mentioned substrate materials. The substrate may be composed of several layers of different materials optionally being glued together, or be a blend of different materials. The substrate may have any size, shape and structure, including an elongated structure, and may be in the form of pieces, threads, fibers, cables, wires, hollow structures, particles, nanoparticles, monolayers etc. Particles and nanoparticles may be uncoated or coated with another material and may further be in the form of aggregates (multiple (nano)particles forming an assembly of individual (nano)particles). Aggregates may in some cases be view ed as one (nano)particle. Substrates may also be composed of one or more of the above mentioned, e.g., the substrate may be a base material comprising glass, silicon, GaAs, GaN, GeS, InP. dielectric material, ceramic, composite, as wells as layered and patterned structures thereof. Substrates may have any form and shape, be elongated, be hollow, have protrusions or recesses, etc.

[0129] An aspect of the present disclosure relates to polymer molecules formed on a surface (surface polymer) of a substrate by providing a substrate, exposing the substrate to a first polymerization initiator, exposing the substrate to a first monomer, exposing the substrate to a second polymerization initiator, and exposing the substrate to a second monomer. The disclosure further relates to surface polymers formed on a surface of a substrate further comprising exposing the substrate to a third polymerization initiator, and exposing the substrate to a third monomer. The disclosure further relates to surface polymers formed on a surface of a substrate further comprising exposing the substrate to a fourth polymerization initiator, and exposing the substrate to a fourth IPTS / 128973811 1monomer. In another aspect, the present disclosure relates to surface polymers formed on a surface of a substrate further comprising exposing the substrate to additional polymerization initiators, and exposing the substrate to additional monomers. Thereby, surface polymers of fourth, fifth, sixth, and so on, polymer molecules may be obtained.

[0130] Within the present context, the term “a first monomer” and “a second monomer” as well as “the first monomer” and “the second monomer” are intended to include one type of first and second monomers, respectively, as well as different types of first and second monomers, respectively. By way of example, two ty pes of first monomers may lead to the formation of first polymer molecules being a copolymer. By way of example, two types of second monomers may lead to the formation of second polymer molecules being a copolymer. The same applies to third, fourth, fifth, etc., monomers.

[0131] An object of the present disclosure is to provide, a surface polymer formed on a surface of a substrate by providing a substrate, exposing the substrate to a first polymerization initiator, exposing the substrate to a first monomer, exposing the substrate to a second polymerization initiator, and exposing the substrate to a second monomer. The so obtained surface polymer may be subjected to a further procedure by exposing the substrate to a third polymerization initiator, and exposing the substrate to a third monomer. The so obtained surface polymer may be subjected to a further procedure by exposing the substrate to a fourth polymerization initiator, and exposing the substrate to a fourth monomer.

[0132] It is an object of the present disclosure to provide a surface polymer formed on a surface of a substrate by exposing a substrate to first polymerization initiators covalently binding to a surface of the substrate, exposing the substrate to a first monomer to form first polymer molecules from the first polymerization initiator sites, exposing the substrate to second polymerization initiators covalently binding to the first polymer molecule, and exposing the substrate to a second monomer to form second polymer molecules from at least the second polymerization initiator sites. It is an object of the present disclosure to provide a surface polymer formed on a surface of a substrate, wherein the average dry film thickness of the surface polymer is at least 0.5 pm. It is an object of the present disclosure to provide a surface polymer formed on a surface of a substrate, wherein the first polymer molecules, and / or the second polymer molecules comprise copolymers.

[0133] IPTS / 128973811 1The surface polymer formed on a surface of a substrate may further be obtained by exposing the substrate to third polymerization initiators covalently binding to at least the second polymer molecules, and exposing the substrate to a third monomer to form third polymer molecules from at least the third polymerization initiator sites. Further, the polymer molecule formed on a surface of a substrate may further be obtained by exposing the substrate to fourth polymerization initiators covalently binding to at least the third polymer molecules, and exposing the substrate to a fourth monomer to form fourth polymer molecules from at least the fourth polymerization initiator sites. Continuing exposing the substrate to further polymerization initiators and further monomers make possible obtaining surface polymers of a complex architecture comprising fourth, fifth, sixth, and so on, polymer molecules.

[0134] For forming the polymer molecules, a reaction composition may be applied. The reaction composition may comprise a monomer, a catalyst, a ligand, an activator, and a solvent. It is to be understood that each polymerization event (i.e., formation of polymer molecules (first, second, third, fourth, fifth, sixth, and so on) involves exposing the substrate with polymerization initiators attached to the substrate, and / or attached to a formed polymer molecule to the reaction composition under conditions enabling addition of monomeric units to form the polymer molecule. The polymerization initiators and the monomers are chosen so as to suit the purposes and properties of the resulting surface polymers.

[0135] Several procedures are available for forming surface polymers on at least a portion of a substrate. Among the procedures for formation of surface polymers, (ARGET) ATRP and SET-LRP are widely used. For the polymerizing chains to propagate, a monomer, a catalyst, a ligand and a solvent are needed. In (ARGET) ATRP and SET-LRP polymerizations, some reactions activate the catalyst, thereby, promoting polymerization, and at the same time, other reactions deactivate the catalyst to impede polymerization, and a suitable equilibrium between activating and deactivating catalyst-ligand species is set to control surface polymer propagation. Both the SET-LRP and (ARGET) ATRP method applies CuCh or CuBn as catalyst in the case of ARGET ATRP, and additionally Cu(0) in the case of SET-LRP. The Cu-catalyzed ARGET ATRP involves a halogen transfer between a dormant halogen capped species, Pn-X and Cu(I)X / L catalyst, resulting in the formation of a propagating radical (Pnradical) and Cu(II)X2. The propagating radical undergoes polymerization with monomers, forming the growing polymer chain. Controlling the ratio between Cu(I)X / L and Cu(II)X2 / L allows in general more control of the polymer propagation.

[0136] IPTS / 128973811 1Surface-Initiated Surface Polymer formation is described in WO 2024 155981 and WO 2019 196999. WO 2019196999 describes the use of a catalyst based on, e.g., a Cu oxide, the Cu forming a dormant complex with the ligand (Cu(II) / L) which may be activated on demand to Cu(I) / L by an oxygen scavenger as catalyst activator, such as sodium ascorbate. The dormant catalytic system described in WO 2019 196999 is halogen free at least to the extent that no halogen source is used to prepare the catalyst / ligand complex in contrast to SET-LRP and ARGET ATRP (use of Cu chlorides or Cu bromides).

[0137] Catalysts to be used herein for forming surface polymers may be selected from transition metals (as defined in the Periodic Table of Elements). In particular, the catalyst may be obtained from Cu, Fe or Ru. Specific examples of such catalysts include CmO. CuO, CuCL CuCk, CuBr, CuBrc, FeCh, FeBrs, Fe2(SO4)3, FeCk, FeBn, FeSCh, RuCk and RuCh hydrateas well as combinations thereof. The catalyst concentration in the reaction composition is typically in the range 0.001-1 mM. The concentration of catalyst in the reaction composition may be in the range 0.02-0.32 mM, for example 0.02 mM, 0.04 mM, 0.08 mM, 0.16 mM, or 0.32 mM. The activator for the catalyst (e.g., an oxygen scavenger) may be used in excess compared to the catalyst. Excess catalyst activator may, e.g., be 10-500 times. The catalyst activator is responsible for the turnover between oxidized deactivating and / or activating catalyst states. It is presently believed that the principal reaction pathway for catalyst activation is reduction, that is, the catalyst activator is a species which is capable of reducing the catalyst of the complex between the catalyst and the ligand from its inactive state to its catalytically active state, where surface polymer formation can take place. Examples of suited catalyst activators are sodium ascorbate, ascorbic acid, hydrazine, hydrazine hydrate, sodium hypophosphite, glucose, glucose with glucose oxidizing enzyme (Gox),tin 2-ethylhexanoate, sodium phenoxide, sodium dithionite, and a mixture of iron powder and sodium chloride.

[0138] Ligands to be used herein include, but are not limited to, nitrogen-containing ligands. Nonlimiting examples of such nitrogen-containing compounds are bi-, tri-, or tetradentate amine ligands (containing two, three or four amine substituents) which are aliphatic and / or aromatic in nature. In particular, such ligands include N,N,N’. N”, A'"'-pentamethyldiethylene-lriamine (PMDETA), tris[2-(dimethylamino)ethyl]amine (MeeTREN). tris(2-aminoethyl)amine (TREN), tris(2-pyridylmethyl)amine (TPMA), HMTETA ( 1,1, 4, 7, 10,10-hexamethyltri ethylenetetramine),

[0139] IPTS / 128973811 1TMEDA (tetramethylethylenediamine), Me4Cyclam (1,4.8, 11 -tetramethyl- 1, 4,8,11-tetraaza-cyclotetradecane), and 2.2’-bipyridyl (BiPy), and combinations thereof. The amount of ligand in the reaction composition is defined as a ratio to the concentration of catalyst in the reaction composition. The ratio of ligand to catalyst in the reaction composition is in the range 0.001:1 -1000:1. The ratio of ligand to catalyst in the reaction composition may be in the range 0.005:1 -100:1, for example 0.13:1, 0.5:1, 1.0:1, 2.0:1, 3.5:1. 7.5:1 or 12:1. In general, excess amount ligand as compared to amount catalyst may be suite.

[0140] The catalyst and the ligand form a complex. One, two, three or even four ligands may form complexes with one catalyst.

[0141] The reaction composition may comprise a solvent. Suitable solvents include but are not limited to alcohols, dipolar aprotic solvents (for examples, tetrahydrofuran, methyl acetate, ethyl acetate, buty l acetate, dimethyl sulfoxide, dimethyl formamide), methylene carbonate, ethylene carbonate, propylene carbonate, ethyl lactate alcohol, toluene, ionic liquids, supercritical CO2. and water, as well as mixtures thereof. In an embodiment, the solvent may be mixture of one or more miscible solvents.

[0142] The reaction composition may further comprise a buffer. Buffers usually are aqueous. Suitable buffers include carbonate buffers, glycine buffers, citrate buffers, phosphate buffers, acetate buffers, ammonium buffers (ammonium chloride / ammonia), formate buffers, sodium ascorbate / ascorbic acid buffers, and / or zwitterionic buffers such as Good’s buffers. Good’s buffer include MES, PIPES, MOPS, HEPES, CHES, CAPSO and / or CAPS.

[0143] The reaction composition may further comprise an additive in the form of a surfactant and / or a polyquatemium compound. Suitable surfactants include sodium dodecyl sulfate (SDS), Triton-Xi 00, dioctyl sodium sulfosuccinate (DOSS), cetrimonium bromide (CTAB), cetrimonium chloride (CTAC), and / or dimethyldioctadecylammonium chloride. Suitable polyquatemium compounds include polyquatemium-7. polyquatemium- 10, polyquatemium- 11, polyquatemium-14, polyquatemium-D 16, polyquatemium-31 , polyquatemium-36, polyquatemium-46, polyquatemium-65, polyquatemium-68, polyquatemium-79.

[0144] The reaction composition may further comprise a halide compound for increasing the “livingness” of the polymerization of monomers. A “living” polymerization refers to a polymerization where IPTS / 128973811 1the rate of termination is minor in comparison to the rate of propagation of polymer molecules from the polymerization initiators. As a result, living polymerizations show a linear relationship between polymer chain length and time. The halide compound to be used herein is a compound capable of providing a halide anion. Non-limiting examples of such compounds are NaCl, NaBr, KC1, KBr, MgCh, MgBn, CaCh, HC1, HBr, LiCl, LiBr, CaBr2, as well as combinations thereof. Halide compounds may disassociate in the reaction composition, generating halide anions which may form complexes with and / or bind to catalysts in solution, resulting in an increased concentration of catalyst / ligand-X (X is the halide anion) complexes which are responsible for end-capping, and thus deactivating, propagating surface polymer chain-end radicals to deliver alkyl halides. Consequently, the number of propagating surface polymer chain-end radicals at any given time is lowered, which may result in at least the following effects. (1) a lowering of the rate with which polymer molecules grow initially due to a lower number of propagating chains, and (2) a lowering of the rate with which chain termination between two propagating polymer molecule chain-end radicals occur (through recombination or disproportionation), leading to an increased living character of the polymerization. In an embodiment, the catalyst is Cu, the ligand is MeeTREN, PMDETA, TREN, HMTETA, TMEDA, or MerCyclam and the halide compound is NaCl.

[0145] In an aspect of the present disclosure, formed polymer molecules may be cross-linked to other formed polymer molecules. Polymer molecules can be cross-linked via several pathways, depending on their structure and chemical functionalities. Generally, a cross-linking molecule must be able to either: react at least with two reactive groups present in the polymer molecules, or, be able to react at least once with reactive groups present in the polymer molecules and generate in this reaction at least one new reactive group, which may react further with neighboring polymer molecules, leading to cross-linking. As an example of the latter, poly(glycidyl methacrylate) (PGMA) contains a reactive oxirane (epoxide)-moiety, which upon reaction with a nucleophile (Nu) yields a hydroxyl group, and a carbon-Nu covalent bond. The formed hydroxyl group may itself be considered a nucleophile and can react with another oxirane moiety of a neighboring polymer molecule, resulting in formation of a carbon-0 covalent bond, which is responsible for the cross-linking of the two polymer molecules. Suitable nucleophiles for reaction with PGMA include but are not limited to amines, thiols, hydroxyls. Examples of nucleophiles which may react only once with PGMA polymer molecules include alcohols such as ethanol and phenol, secondary amines such as diethylamine, and thiols such as 1 -decanethiol. Examples of nucleophiles that may react at least twice with PGMA polymer molecules include primary amines IPTS / 128973811 1such as allyl amine and propyl amine, diamines such as 1 ,2-diaminoethane, diols such as ethylene glycol and bisphenol A, and dithiols such as ethylene bis(thioglycolate). Cross-linkers which may react e.g. at least three times can be conceptualized by e.g. branched triamines such as propane-1,2, 3-amine, and glycerol. In order for a molecule to cross-link polymer molecules that contain nucleophilic functional groups such as hydroxyls and amines, the cross-linker molecule must have at least two reactive electrophilic sites. Examples thereof include di-acid halides such as succinyl chloride, adipoyl chloride, fumaryl chloride and azealoyl chloride, or dicarboxylic acids such as maleic acid, glutaric acid, and terephthalic acid, which may be activated by suitable reagents such as carbodiimides like l-ethyl-3-(3-dimethylaminopropyl)carbodiimide, diisopropylcarbodiimide, orN,N'-dicyclohexylcarbodiimide, or acid halide forming species such as thionyl chloride.

[0146] In an aspect of the present disclosure, a method for forming a surface polymer of polymer molecules on a substrate is provided, the method comprising providing a substrate, exposing the substrate to a first polymerization initiator, exposing the substrate to a first monomer, exposing the substrate to a second polymerization initiator, and exposing the substrate to a second monomer.

[0147] The method may further comprise exposing the substrate to a third polymerization initiator, and exposing the substrate to a third monomer. The method may further comprise exposing the substrate to a fourth polymerization initiator, and exposing the substrate to a fourth monomer. The method may further comprise fifth, sixth, and so on, further exposure to fifth, sixth, and so on, respectively, polymerization initiators, and exposing the substrate to fifth, sixth, and so on, monomers.

[0148] In an aspect of the present disclosure, the method comprises providing a substrate having first polymerization initiators covalently bound to a surface of the substrate, exposing the substrate to a reaction composition comprising a first monomer to form first polymer molecules covalently bound to first polymerization initiator sites, exposing the substrate to a second polymerization initiator covalently binding to the first polymer molecules, and exposing the substrate to a second monomer to form second polymer molecules covalently bound to the first polymer molecules. The method may further comprise exposing the substrate to third polymerization initiators covalently binding to at least the second polymer molecules, and exposing the substrate to a third monomer to form third polymer molecules from at least the third polymerization initiator sites. The method may further comprise exposing the substrate to fourth polymerization initiators IPTS / 128973811 1covalently binding to at least the third polymer molecules, and exposing the substrate to a fourth monomer to form fourth polymer molecules from at least the fourth polymerization initiator sites. The method may further comprise exposing the substrate to fifth, sixth, and so on, polymerization initiators, and exposing the substrate to fifth, sixth, and so on, monomers to form fifth, sixth, and so on, polymer molecules from at least the fifth, the sixth, and so on, polymerization initiator sites. It is to be understood that polymer molecules may be formed from polymerization initiators present on previously polymerization initiator-modified sites which have not been polymerized from in previous polymerization events. Thus, third monomeric units may propagate from second polymerization initiators in addition to propagation from third polymerization initiators. The same applies to fourth monomers which may propagate from second, third, and fourth polymerization initiators.

[0149] A surface polymer composed of polymer molecules formed on the substrate has an average dry film thickness of at least 0.5 pm may be provided by the method. A surface polymer composed of polymer molecules formed on the substrate having an average dry film thickness of at least 1 pm may be provided by the method. The method as disclosed herein may be used to provide surface polymers on the surface of a substrate, the surface polymers having an average dry film thickness of at least 2 pm, at least 5 pm, or at least 8 pm.

[0150] In the method, a reaction composition as defined above may be applied for forming the surface polymer. As mentioned above, the reaction composition may comprise a monomer, a catalyst, a ligand, an activator, and a solvent. The catalyst may be selected from the catalysts defined above. In particular, the catalyst may be obtained from Cu, Fe, or Ru. The reaction composition to be applied in the method may comprise a ligand as defined above. In particular, the ligand may be selected from N,N,N N”, A”’-pentamethyldiethylene-triamine (PMDETA), tris[2-(dimethyl-amino)ethyl] amine (MeeTREN), tris(2-aminoethyl)amine (TREN), tris(2-pyridylmethyl)amine (TPMA), 1,1, 4, 7, 10,10-hexamethyltri ethylenetetramine (HMTETA), tetramethylethylenediamine (TMEDA), l,4,8,ll-tetramethyl-l,4,8,ll-tetraazacyclotetradecane ( Me-iCy -clam), and / or 2,2’ -bipyridyl (BiPy). The reaction composition to be used in the method may comprise an activator. Suitable activators may be oxygen scavengers as defined above. In particular, the activator may be selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOX, and / or pyrogallic acid. The reaction composition to be used in the method may further comprise a buffer. Suitable buffers are defined above. The reaction composition to be used in the method IPTS / 128973811 1may further comprise a halogen salt (metal halide). Suitable halogen salts are defined above. The reaction composition to be used in the method may comprise a surfactant. Suitable surfactants are defined above. The reaction composition to be used in the method may further comprise an additive in the form of a surfactant and / or a polyquatemium compound. Suitable additives are as defined above.

[0151] The polymerization initiators (first, second, third, fourth, fifth, sixth, and so on) for the method may suitably be selected from the polymerization initiators defined above. The monomers (first, second, third, fourth, fifth, sixth, and so on) for the method may suitably be selected from the monomers defined above.

[0152] In the method, the grafting density of the first polymerization initiator may be controlled as described above. In particular, a certain ratio between first polymerization initiators and nonpolymerization initiators (“dummy initiators”) may be used in the step for attaching the first polymerization initiator. Suitable ratios are given above. The grafting density of the first initiator may further be controlled by converting a portion of the first polymerization initiators to nonpolymerization initiators. The procedures for such conversion are described above. Likewise, the grafting density of the second, third, fourth, fifth, sixth, and so, polymerization initiators may be controlled.

[0153] For forming surface polymers of polymer molecules, the substrate and the reaction composition as defined herein are typically kept in contact with each other for a suitable period (residence time), such as from 30 seconds to 5 hours. The residence time includes, but is not limited to 30 seconds, 1 minute. 5 minutes. 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours and 5 hours. The surface polymer formation may take place at ambient temperature (room temperature), or with cooling or heating. Suitable temperatures are such from 20°C up to 120°C, such as from room temperature (approximately 20°C) to 120°C. Specific temperatures include, but are not limited to, 20°C, room / ambient temperature (approximately 20°C), 30°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C. and 120°C. The residence time and temperature during the residence time may suitably be computer controlled. The above conditions may suitably be applied in any of the steps for forming surface polymers of polymer molecules, that is, for forming first, second, third, fourth, fifth, sixth, and so on, polymer molecules. Following formation of surface polymers, the substrate may be subjected to a rinsing and cleaning process, typically flushing with a suitable solvent, sonicating, and / or drying.

[0154] IPTS / 128973811 1Here the formation of the first polymerization initiator layer is described in more detail. In order to apply the “grafting from” approach for forming surface polymers of polymer molecules, a first polymerization initiator is usually introduced to one or more surfaces. Polymerization initiators as such may in general terms be described as a halide-containing molecule where at least one halide is present on or in alpha position relative to a radical stabilizing moiety, such as (but not limited to) esters, aromatics rings or sulfonyls. As such, a polymerization initiator is a molecule able to undergo atom transfer, i.e., the transfer of a halogen from the initiator to an activating species, and from a deactivating species to the propagating radical located on the initiator residue. When the radical is located on the initiator residue, the radical can propagate monomeric units, forming polymeric molecules. In Fig. 3, a few examples of polymerization initiators are shown (the curved line denotes the substrate and optionally any chemistry linking the polymerization initiator functional group to the substrate). Thus, the three examples in Fig. 3 are suitable for initiating polymerization reactions. The examples in Fig. 3 include: Left: a chloromethyl phenyl fragment, middle: a 2-bromoisobutyryl fragment, right: a sulfonyl chloride fragment. In general, tertiary bromine moieties, benzylchloride moieties, and methylchloride (chloromethyl (CM)) moieties may be suited for providing polymerization initiator sites.

[0155] Here attachment of subsequent polymerization initiators (first, second, third, fourth, fifth, sixth, etc.) is described in more detail. Polymerization initiators may be attached to formed polymer molecules. Usually, the attachment involves a chemical reaction using certain moieties present on the polymer molecule. Generally nucleophilic moieties on the polymer molecules may react with electrophilic moieties on the subsequent polymerization initiator molecules, exemplified by e.g., the reaction between hydroxyl groups on poly(2-hydroxyethyl methacrylate) and alphabromoisobutyryl bromide (BiBB), or the condensation reaction between hydroxyl groups on e.g., poly(2-hydroxyethyl methacrylate) and the siloxane functionality of p-(chloromethyl)-phenyltrimethoxy silane (CPTMS). As another example, the sulfonate functionality of poly(3-sulfopropyl methacrylate) may be converted to the sulfonyl chloride functionality through reaction with a chlorinating substance such as thionyl chloride, oxalyl dichloride, or phosphorous pentachloride. Still another example is the installation of a CM moiety.

[0156] In accordance with the disclosure above, interesting surface polymers may be those indicated below. The surface polymer mentioned in the table below (Table 1) may be formed on any type of substrate and may further be formed on build-up layer of, e.g., ABF.

[0157] IPTS / 128973811 1Table 1. Surface polymer examples.

[0158]

[0159] An object of the present disclosure is to provide a device structure comprising a surface polymer as described herein, composed of polymer molecules. The device structure may comprise a substrate and surface polymer as defined herein, and further comprise a layer of material over the IPTS / 128973811 1surface polymer, the layer of material being physically and / or chemically bonded to the surface polymer, wherein the material of the layer and the material of the substrate have different coefficients of thermal expansion. The device structure may be such, wherein the substrate may be a glass substrate (or a substrate comprising glass) and the layer of material may be a metal layer. The device structure may be such, wherein the surface polymer accommodates stress between the glass substrate and the metal layer over a temperature change of at least 100 Kelvin. The device structure may be such, wherein the surface polymer accommodates stress between the glass substrate and the metal layer over a temperature change of at least 200 Kelvin. The device structure may be such, wherein the polymer accommodates stress between the glass substrate and the metal layer over a temperature change of at least 300 Kelvin. The device structure may be such, wherein the metal layer is a copper layer. The device structure may be such, wherein the surface polymer has an average dry film thickness of at least 0.5 pm. The device structure may be such, wherein the surface polymer has an average dry film thickness of at least 1 pm. The device structure may be such, wherein the surface polymer has an average dry film thickness of at least 2 pm. The device structure may be such, wherein the surface polymer has an average dry¬ film thickness of at least 5 pm. The device structure may be such, wherein the surface polymer has an average dry film thickness of at least 8 pm.

[0160] The layer of material may, e g., be metal -containing. The layer of material may be deposited, on the substrate with surface polymers, by an electroless (ELESS) process, and electroplating (EP) process, a physical vapor deposition (VPD) process, chemical vapor deposition (CVD) process, or atomic layer deposition (ALD) process, or a combination of these methods. Non-limiting examples of deposited materials include copper (Cu). nickel (Ni), nickel-phosphorus (Ni-P), nickel-phosphorus-diamond (Ni-P-D) composite, nickel gold (Ni-Au), nickel-boron (Ni-B), palladium (Pd), palladium-nickel (Pd-Ni), and silver (Ag).

[0161] The Young's modulus (E) is a property- of the material that tells us how easily it can stretch and deform and is defined as the ratio of tensile stress (o) to tensile strain (s), where the stress is the amount of force applied per unit area (o = F / A), and the strain is extension per unit length (e = dl / 1). Young’s module may thus be used to predict a materials’ stress accommodation.

[0162] Young's modulus of a material in the linear elastic region may be expressed by the equation:

[0163] <y

[0164] E = - E

[0165] IPTS / 128973811 1Young's modulus (E) is expressed by the units of pressure, typically Pascals (Pa). The equation that connects stiffness (k) of material to Young’s modulus (E) is:

[0166] EA

[0167] k= T

[0168] where A is the cross-sectional area and L is the original length of the material. The equation shows a linear dependency of stiffness (k) with respect to the Young’s modulus (E). implying that the smaller the Young’s modulus, the softer the material and the easier it is to deform.

[0169] Glass transition temperature (Tg) is the temperature at which an amorphous or semicrystalline polymer transitions from a hard, brittle state to a rubbery’, flexible state. Below Tg, the polymer is hard, brittle and has higher Young’s modulus (E) due to the polymer chains being “frozen” in their place because of restricted bond rotation. As the temperature rises and approaches Tg, the polymer chains move more freely and transition into a rubbery state with low Young’s modulus (E). Therefore, the behavior of polymeric materials or polymer films in response to external stresses, such as pressure, is influenced by whether the temperature is above or below Tg for the material.

[0170] Combining different materials having different coefficients of expansion during heating may cause certain issues with the materials cracking or even breaking. An example of such materials is glass and metal, e.g., in semiconductors.

[0171] The inventors believe that the incorporation of surface polymers as described herein may act as a stress accommodating layer between different materials. For example, a surface polymer film as described herein may be incorporated within a through glass via (TGV) between the glass surface and the TGV metal filling (e.g., by an Eless, EP, PVD, CVD, or ALD process). The stress accommodating efficiency of the surface polymer may in some cases be increased, e.g., when the Tg of the surface polymer film is below the working temperature of the TGV due to certain surface polymer films being softer and more rubbery at higher temperatures.

[0172] In Fig. 10, a cross-sectional representation of a device structure is shown, the device structure comprising a substrate 1010, a film of surface polymer 1020, and a layer of material 1030, wherein the layer of material 1030 and the material of the substrate 1010 have different coefficients of thermal expansion, and the surface polymer film 1020 acts as a stress accommodation layer. The film of surface polymer 1020 is formed on the substrate 1010 according to methods disclosed

[0173] IPTS / 128973811 1herein and is covalently bonded to a surface of the substrate. The layer of material 1030 is formed on the surface polymer film 1020 and is chemically or physically bonded to the surface polymer film. The substrate 1010 may be silicon, glass, or another material. The layer of material 1030 may be a metal, such as copper, or another material. The surface polymer thick film 1020 may be greater than 0.5 pm, greater than 1 pm, greater than 2 pm, greater than 5 pm, or greater than 8 pm thick (as determined by ellipsometry). The surface polymer film 1020 may be engineered (by selecting thickness, specific surface polymer or surface polymers, extent of cross linking, etc.) to accommodate stress due to a temperature change of at least 100 Kelvin, at least 200 Kelvin, at least 300 Kelvin, etc. The surface polymer 1020 may comprise copolymers.

[0174] An object of the present disclosure is to provide a system for forming surface polymers on a surface of a substrate. Fig. 11 shows a schematic representation of a wet chemistry system for forming films of surface polymer on substrate surfaces. A cassette 1110 loaded with substrates is movable by a substrate displacement device (not shown) such as one or more robots or a conveyor system with the capability to move substrate holders horizontally and vertically in and out of containers and from container to container. The containers 1120, 1130, 1140 and 1150 contain w et chemistry for the different process steps as needed for forming thick films of surface polymers on the substrates, as described in detail herein.

[0175] According to embodiments, a system for forming surface polymers according to methods described herein, may comprise a first container containing a reaction composition for forming the first polymer molecules at first polymerization initiator sites on the surface of the substrate, a second container containing chemistry for forming second polymerization initiator sites on the first polymer molecules, a third container for forming second polymer molecules on the first polymer molecules at the second polymerization initiator sites, and a substrate displacement device for bringing at least a portion of first polymerization initiator-modified substrate into contact with the reaction composition in the first container for a first controlled time, wherein the controlled time is sufficient for first polymer molecules to be formed on the portion of the polymerization initiator-modified substrate, then for bringing the at least a portion of the substrate into contact with the chemistry in the second container for a second controlled time, wherein the second controlled time is sufficient for second initiator sites to be formed on the first polymer molecules, and then for bringing the at least a portion of the substrate into contact with the reaction composition in the third container for a third controlled time, wherein the third controlled time is sufficient for second polymer molecules to be formed on the second initiator sites on the first IPTS / 128973811 1polymer molecules. The process may be extended with further forming of polymerization initiator sites and further forming of polymer molecules, as needed. The process may be for forming polymer molecules being copolymers. Furthermore, extra containers may be added as needed for rinsing, drying, annealing, etc. between processes. A container for drying may be an oven. A container for annealing may be an oven. A container for attaching polymerization initiators may be a vacuum oven or a container holding a polymerization initiator chemistry. The containers for attaching polymerization initiators may hold a non-polymenzation initiator in a certain ratio relative to the polymerization initiator. The substrate displacement device may be one or more robots or a conveyor system with the capability7to move wafer holders horizontally and vertically in and out of containers and from container to container.

[0176] The objectives of the present disclosure are illustrated by the below, non-limiting examples.

[0177] Examples

[0178] List of materials used in the Examples:

[0179] Throughout the examples, Dl-water refers to tap water deionized using a deionizing equipment (Silhorko with M22-F softening plant, RO Bl -2 Reverse Osmosis plant and Silex 2BS mixed bed plant). The Dl-water has a conductivity7of <0.5 pS / cm, indicating an ultrapure quality7with very7low presence of ions. The quality7of the Dl-water was confirmed at least weekly. Dl-water holds a conductivity of less than 0.5 pS / cm, indicating very low presence of ions, below 0.1 mg / L. Silicon wafer substrates. Test CZ-Si wafer, 4 inch, thickness = 525 ± 25 pm, (100), p-type (Boron), were purchased from MicroChemicals GmbH (r = 5.08 cm) and cut into 1 / 4th of a wafer. Glass substrates BF33.

[0180] Coming Eagle Glass XG (Eagle glass) substrates 100x100x0.7 mm, 2-side polished, purchased from MTI Corporation 100x100x0.7 mm.

[0181] Ammonia (25% p. a) was purchased from Chemsolute.

[0182] Acetone (>99%) was purchased from Chemsolute.

[0183] Acetonitrile (MeCN) (min. 99.9 %) was purchased from Chemsolute

[0184] Dimethylsulfoxide (DMSO) (> 99 %) was purchased from Tokyo Chemical Industry.

[0185] Dichloromethane (DCM) (99.9 %) was purchased from ChemSolute.

[0186] Dimethylformamide (DMF) (99.9%) was purchased from Chemsolute.

[0187] Toluene (99.8%) was purchased from Chemsolute.

[0188] ABC clean A200 was purchased from ABC-Clean ApS.

[0189] p-(Chloromethyl)phenyltrimethoxysilane (CPTMS) (95%) was purchased from Gelest.

[0190] IPTS / 128973811 1Phenyltrimethoxysilane (PTMS) (>98.0%) was purchased from Tokyo Chemical Industry', tris [2-(Dimethylamino)ethyl] amine (MesTREN) (>98% ) was purchased from from abcr or Alfa Aesar.

[0191] tris(2-Pyridylmethyl)amine (TP MA) (98%) was purchased from Tokyo Chemical Industry. N,N,N',N",N''-Pentamethyldiethylenetriamine (PMDETA) (99%) was purchased from Sigma Aldrich.

[0192] Copper(II)chloride dihydrate (CuCh 2H2O) (99.0%) was purchased from Sigma Aldrich.

[0193] Methyl methacrylate (MMA) (99 %, 30 ppm MEHQ inhibitor) was purchased from Sigma Aldrich (lot no. STBK8834).

[0194] 2 -Hydroxy ethyl methacrylate (HEMA) (99 %, <250 ppm MEHQ inhibitor) was purchased from Sigma Aldrich

[0195] Glycidyl methacrylate (GMA) (> 97 %) was purchased from Sigma Aldrich,

[0196] tert-butylmethacrylate (tBMA) (>98% ) was purchased from TCI Chemicals.

[0197] n-Butylmethacry late (BuMA) (>99% ) was purchased from TCI Chemicals.

[0198] Benzylmethacrylate (BnzMA) (98% ) was purchased from Alfa Aesar

[0199] 2-Ethylhexyl methacrylate (EHMA) (98% ) was purchased from Sigma Aldrich.

[0200] 2 -Hydroxy ethyl acrylate (HEA) (96%) was purchased from Sigma Aldrich.

[0201] Triethyl amine (TEA) (>99%) was purchased from Sigma Aldrich.

[0202] 4-Dimethylaminopyridin (DMAP) (>99.0%) was purchased Tokyo Chemical Industry.

[0203] a-Bromoisobutyryl bromide (BiBB) (98%) was purchased from Sigma Aldrich.

[0204] Sodium ascorbate (NaAsc) (98%) was purchased from Sigma Aldrich.

[0205] Acetic acid (AcOH) (99.0%) was purchased from ChemSolute.

[0206] Sulphuric acid, concentrated (H2SO4) (95.0-97.0%) was purchased from ChemSolute.

[0207] Paraformaldehyde (95 %) was purchased from Sigma Aldrich.

[0208] Chlorotrimethylsilane (TMS-C1) (> 98%) was purchased from Sigma Aldrich.

[0209] Tin(IV)chloride (SnCI i) (98%, anhydrous) was purchased from abcr.

[0210] Triethyl amine (Et3N) (>99%) was purchased from Chemsolute.

[0211] Acetyl bromide (AcBr) (>99%) was purchased from Sigma Aldrich.

[0212] List of catalyst solutions:

[0213] Catalyst M: Me6TREN (76 pL), Dl-water (15.924 rnL), and Cu(II) (324 mg / L, obtained from a solid copper source by stirring or otherwise mixing prior to mixture with ligand and Dl-water). Catalyst T: TPMA (84 mg), MeCN (7 mL) and 9 mM CuCh 2H2O (aq.) (7 mL).

[0214] Catalyst P: PMDETA (0.06 mL), CuC12-2H2O (13.6 mg) and Dl-water (16 mL).

[0215] IPTS / 128973811 1List of equipment used in the Examples:

[0216] •‘Big sonicator" refers to an ULTRASONIC CLEANER PROCLEAN 28.0 from Ulsomx (40 kHz, 480 W).

[0217] “Sonicator” refers toto a Bandelin Sonorex Super RK100 sonicator (35 kHz ultrasound frequency, 80 W nominal ultrasonic power).

[0218] “Vacuum oven7’ refers to a Faithful Vacuum Drying Oven-DZ-BCII.

[0219] “Oven” refers to a Binder model FD 56.

[0220] Ellipsometry was measured on a J. A. Woollam M-2000 Ellipsometer. This instrument was set to measure 10 points on each substrate. Each point was analyzed using a Cauchy model providing a thickness and a Mean Square Error (MSE), the latter referring to the goodness of the fit. Thicknesses are thus given as the average of all measured points on the substrate. Unless specifically stated otherwise, 10 data points were obtained on each substrate unless otherwise stated. Standard deviation is the standard deviation based on the entirety of the measured thicknesses. The standard deviation is an estimate of the homogeneity of a surface polymers formed.

[0221] Infrared Reflection Absorption Spectroscopy (IRRAS) was measured on a Nicolet 6700 FTIR Spectrometer (Thermo Fisher Scientific, Denmark), equipped with a liquid nitrogen-cooled narrow-band mercury' cadmium telluride (MCT / A) detector. The spectral resolution was 4 cm'1, and 100 spectra were recorded and averaged for each measurement. The spectra were recorded in dry air, at room temperature. The substrates were irradiated with p-polarized light, at an angle of approximately 65°. The spectra were baseline corrected using the OMNIC 8.2 software.

[0222] Water contact angles (WCA) were measured on a Kriiss Mobile Surface Analyzer. In 5 separate points, the contact angle of a Dl-water and a CH2I2 drop is measured. Using the software ADVANCED v. 1.14, the surface free energy (SFE) can be calculated. The SFE indicates the maximum surface tension of a liquid that wets a solid surface, under ideal conditions. Accordingly, a material with a high SFE is easier to wet than a material with a lower SFE, and low SFE materials will generally exhibit higher water contact angles than those materials with a higher SFE.

[0223] Example 1

[0224] Pre-cleaning of silicon wafer substrates

[0225] The example describes a procedure for pre-cleaning substrates prior to surface polymerization. The total number of substrates pre-cleaned for subsequent examples may vary.

[0226] IPTS / 128973811 1Racks holding the substrates were placed in a 3.75% aqueous solution of ammonia and sonicated for 10 minutes. Then, the substrates were flushed with Dl-water and sonicated in Dl-water for 10 minutes using a big sonicator. Thereafter, the racks holding the substrates were transferred to a 5% solution of ABC clean A200 and sonicated for 10 minutes with previously described equipment. This step was followed by flushing the substrates in Dl-water and sonicating the substrates in Dl-water for 5 minutes with previously described equipment. Finally, the substrates were flushed with acetone and left to dry at room temperature.

[0227] Example 2

[0228] Chemical vapor deposition of (p-chloromethyl)phenyltrimethoxysilane (first polymerization initiator) to produce surface attached initiators (first polymerization initiators)

[0229] The example illustrates a procedure for covalently attaching polymerization initiators (first polymerization initiator) to a substrate (in this case Si substrate).

[0230] Silicon wafer (Si) substrates, pre-cleaned as described in Example 1, were used for surface initiator-modification with CPTMS polymerization initiators using a chemical vapor deposition method.

[0231] The substrates were placed in a rack and placed in a vacuum oven with 16 vials of 100 pL CPTMS (polymerization initiator liquid) at approximately 100°C for 30 minutes. The gauge pressure was lowered to -1.0 bar, whereby the CPTMS evaporated, and the substrates were left for 30 minutes in the vapor. The surface modification was verified using WCA. The surface free energy (SFE) for both blank Si substrates and CPTMS-modified Si substrates are provided in Table 2. Compared to the blank Si substrate the CPTMS-modified substrate displays lowered SFE, indicative of an increased hydrophobicity caused by the successful attachment of the organic CPTMS layer.

[0232] Table 2. Surface free energy of untreated (blank) and CPTMS-modified surface substrates.

[0233]

[0234] Importantly, it is recognized by the inventors that by yielding a lower surface free energy’ from the reaction the substrate is coated with the -Cl moiety. Additionally, it is expected that essentially all available sites on the substrate surface are modified with first polymerization initiators. IPTS / 128973811 1Example 3

[0235] Polymerization from second polymerization initiators on first polymer molecules versus polymerization from end functionalities on first polymer molecules

[0236] In this supporting experiment, 2 substrates (substrate Si) with a first polymer molecule were produced (Si-PHEMA. first polymerization initiator CPTMS, first polymer molecule PHEMA). Subsequently, one of these substrates was subjected to an acylation process to form the polymer molecule bound initiator (second polymerization initiator BiBB): Si-PHEMA-BiBB. The other substrate was not subjected to modification with the second polymerization initiator.

[0237] To form the first polymer molecule on the substrates, the CPTMS-modified substrates were exposed to the following reaction composition and polymerization procedure:

[0238] To a glass container (Container A), Catalyst M (16 mL) was added followed by Dl-water (180 mL), and HEMA monomer (15 mL). In a separate container (Container B) a solution of NaAsc (800 mg in 3 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for polymerization.

[0239] 4 CPTMS-initiator-modified substrates (substrate Si, first polymerization initiator CPTMS), precleaned as described in Example 1 and subjected to initiator-modification as described in Example 2, were placed in a reaction container and the content of Container A was poured into the reaction container. The substrates were left in the reaction composition for 20 minutes and were subsequently withdrawn and cleaned by sonication for 5 minutes in Dl-water. followed by¬ sonication for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrates having first polymer molecules covalently bond to the CPTMS initiator sites (Si-PHEMA) were subjected to ellipsometry to measure the average dry film thicknesses of the formed (collapsed) surface polymer of first polymer molecules (PHEMA polymer brushes). Below, the average dry film thickness is reported as an average of the 4 substrates in Table 3.

[0240] Initiator-modification (second polymerization initiator BiBB) of the Si-PHEMA substrates were prepared as follows: To a reaction container, DCM (50 mL), TEA (0.35 mL) and BiBB (3.1 mL) were added. 2 Si-PHEMA substrates, prepared above, were submersed into the solution, and left IPTS / 128973811 1to react for 36 minutes and were subsequently cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the 2 second initiator-modified substrates (Si-PHEMA-BiBB) were analyzed by ellipsometry to confirm BiBB-initiator modification, and the average dry film thicknesses were determined. The average of the 2 substrates are reported in Table 3.

[0241] After the addition of the second polymerization initiator to the first polymer molecule, a thickness increase was observed. The result of the BiBB-initiator modification is an acylation of the free hydroxyl group in the HEMA side chain moiety. Considering one repeating unit in the surface polymer structure, this acylation would add to the molecular size of the repeating unit, hence an increase of the surface polymer molecular weight was expected. This was indeed observed as an increase in molecular weight would directly result in an increase in the surface polymer molecule (in accordance with h=oMn / pNA).

[0242] The polymerization of 1 Si-PHEMA substrate and 1 Si-PHEMA-BiBB substrate was investigated subsequently. It is hypothesized that, with the polymer molecule bound initiator (Si-PHEMA-BiBB), a significant increase in surface polymer thickness (combined surface polymer) will be observed upon further polymerization, whereas polymerization of not BiBB-initiator modified substrate (Si-PHEMA) will result in minor increase in surface polymer thickness (insofar the Si-PHEMA substrate has viable chain ends able to initiate further polymerization.

[0243] The second polymerization was performed as follows: To a glass container (Container A), Catalyst P (16 mL) was added followed by Dl-water (375 mL), iPrOH (537 mL) and tBMA monomer (75 mL). In a separate container (Container B) a solution of NaAsc (4000 mg in 15 mL Dl-water) was prepared. The content of Container B w as poured into Container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0244] The 4 substrates, 1 Si-PHEMA and 1 Si-PHEMA-BiBB, were placed in a reaction container and the content of Container A was poured into the reaction container. The substrates w ere left to react for 7.5 minutes and were subsequently cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the IPTS / 128973811 1substrates were subjected to ellipsometry to measure the average dry' film thicknesses of the formed (collapsed) combined surface polymer (Si-PHEMA-PtBMA and Si-PHEMA-BiBB-PtBMA). Below, the average dry film thickness of each substrate is reported (see Table 3).

[0245] Table 3. Average dry film thicknesses.

[0246]

[0247] The yielded surface polymer thickness of the Si-PHEMA-BiBB-PtBMA substrate was 3 times higher compared to the Si-PHEMA-PtBMA substrate. By adding the polymer bound initiator (second polymerization initiator) to a Si-PHEMA substrate (Si-PHEMA-BiBB substrate), the number of initiators per square nanometer increases (z. e. the polymerization initiator density on the first polymer molecules). The PHEMA polymer molecule has free -OH groups in its side chains which can be subjected to an acylation reaction to form a polymer molecule-bound second initiator. Thus, polymerization initiator sites are available during a second polymerization, hence, leading to a higher combined surface polymer molecule thickness as compared to a polymerization from end chain functionalities (block polymerization, end chain polymerization of Si-PHEMA substrate).

[0248] A minor thickness increase was observed in the case of the Si-PHEMA-PtBMA substrate (block copolymer formation). This was expected as a surface polymer formed under “living” conditions has possible viable chain-ends able to reinitiate polymerization subsequently. However, as one polymer chain only has one chain-end, the number of viable polymerization initiators after the first polymerization is limited, z. e. , the number of polymerization initiators per square nanometer is constant and cannot be changed. If subjected to a subsequent polymerization event, the average dry film thickness will increase as a second polymer molecule is formed (block polymer) from the viable end chains, however, to a much lesser degree as compared to a first polymer molecule having polymer molecule bound second polymerization initiators (thus, a “macroinitiator” is

[0249] IPTS / 128973811 1formed from the surface polymer having first polymer molecules modified with a second polymerization initiator).

[0250] With this experiment, the inventors have shown the benefits of utilizing a unique first polymer molecule able to undergo a chemical modification to add a surface polymer molecule-bound second polymerization initiator to increase the overall thickness upon a second polymerization event to form a surface polymer composed of two polymer molecules.

[0251] Examples 4

[0252] Surface polymer with an average dry film thickness >500 nm (0.5 yin)

[0253] The example shows the preparation of substrates having a surface polymer with an average dry¬ film thickness above 0.5 pm.

[0254] To form the surface polymer, the following reaction composition and procedure were applied:

[0255] To a glass container (Container A), Catalyst T (16 rnL) was added followed by Dl-water (132 mL), THF (17.6 mL), and HEMA monomer (44 rnL). In a separate container (Container B) a solution of NaAsc (800 mg in 3 mL Dl-water) was prepared. The content of Container B was poured into Container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0256] 1 CPTMS-modified substrate (substrate Si, first polymerization initiator CPTMS), pre-cleaned as described in Example 1 and modified as described in Example 2, was placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrate was left in the reaction composition for 120 minutes and was subsequently flushed with Dl-water, then EtOH, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrate having first polymer molecules covalently bond to the CPTMS initiator sites (Si-PHEMA) was subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer of first polymer molecules (PHEMA polymer brushes). Below7, the average dry film thickness is reported (see Table 4).

[0257] IPTS / 128973811 1The obtained polymer molecule-modified substrate was exposed to a second polymerization initiator (BiBB). To a reaction container, DMF (186 mL), TEA (1.4 mL) and BiBB (12.4 mL) were added. The 1 Si-PHEMA polymer molecule-modified substrate was submersed into the solution and left to react for 3 hours and was subsequently cleaned by sonication for 5 minutes in DCM. Subsequently, the substrate was sonicated for 10 minutes in acetone, before being left to dry (ambient temperature, ambient pressure). After cleaning and drying, the second polymerization initiator-modified substrate (Si-PHEMA-BiBB) was analyzed by ellipsometry. The average dry film thickness is reported in Table 4.

[0258] After the addition of the second polymerization initiator to the first surface polymer molecule, a thickness increase was observed. The result of this reaction is an acylation of the free hydroxy¬ group in the HEMA side chain moiety. Considering one repeating unit in the surface polymer structure, this acylation would add to the molecular size of the repeating unit, hence leading to an increase of the surface polymer molecular weight. This was indeed observed as an increase in overall thickness determined (in accordance with h=oMn / pNA).

[0259] Second polymer molecules were formed from the second polymerization initiators as follows:

[0260] To a glass container (Container A), Dl-water (484 mL), Catalyst M (16 mL), EtOH (410 mL), NaCl (58.4 g) and MMA monomer (75 mL) were added. In a separate container (Container B) a solution of NaAsc (4000 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A and the reaction was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0261] The second polymerization initiator-modified substrate (Si-PHEMA-BiBB) was placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrate was left for 80 minutes in the reaction composition and was subsequently cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrate was subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) combined surface polymer (Si-PHEMA-BiBB-PMMA). Below, the average dry- film thickness is reported (see Table 4).

[0262] IPTS / 128973811 1Table 4. Average dry film thickness.

[0263]

[0264] Amazingly, modifying a surface polymer with surface polymer bound second polymerization initiators (initiators bound to PHEMA), the inventors found that a final surface polymer thickness well above 500 nm can be obtained. It was noted by the inventors that after each process step a color change on the surface was observed. This is coherent with the film thickness resulting in thin film interference with the surrounding light. Inspection of the substrate by the naked eye confirmed that changes to surface polymers took place (change in appearance of color). Also, the distribution of the surface polymers appeared to be very' homogeneous by visual inspection of variations in appearance. Further, by preparing a first polymer molecule which initially is “longer’ (higher thickness of Si-HEMA, thickness controlled by polymerization conditions) relative to what was utilized in Example 3, the initiator density is greatly increased after the formation of the surface polymer-bound second polymerization initiator resulting in an extraordinary thickness of the combined surface polymer after the formation of the second polymer molecule. These findings are surprising since the interplay between the density of initiators, propagating polymer radicals, and the final obtained thickness are not straightforward. A very' high spatial densify of polymerization initiators, and thus a high spatial density of propagating radicals could be expected to lead to a large number of chain-end terminations through, e.g., radical-radical couplings. Such termination events result in “dead” chain ends which cannot propagate further, and as such they are detrimental to the objective of forming very thick surface polymer films. Hence, the growth to well above 500 nm from a surface polymer film with a very' high spatial densify of polymerization initiators speaks to the robustness of the polymerization method described here.

[0265] Examples 5

[0266] Preparing surface polymers having an average dry' film thickness >1 um

[0267] The example shows the preparation of a surface poly mer having an average dry' film thickness above 1 pm.

[0268] The procedure and reaction composition for forming the surface polymer are described below. IPTS / 128973811 1To a glass container (Container A), Dl-water (665 mL), MeCN (85 mL) and HEMA monomer (220 mL) and Catalyst T (16 mL) were added. In a separate container (Container B) a solution of NaAsc (4000 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0269] 1 CPTMS-modified substrate (substrate Si, first polymerization initiator CPTMS), pre-cleaned as described in Example 1 and 5 CPTMS-modified substrates (substrate EG glass, first polymerization initiator CPTMS), pre-cleaned as described in Example 12. Both types of substrates were CPTMS-modified as described in Example 2. The substrates were placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrates were left in the reaction composition for 120 minutes and was subsequently flushed with Dl-water, then EtOH, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, a substrate having first polymer molecules covalently bond to the CPTMS initiator sites (Si-PHEMA) was subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer of first polymer molecules (PHEMA polymer brushes). For PHEMA surface polymers on EG substrates, it is not possible to determine the average dry film thickness directly as ellipsometry is not suited for glass. As the two types of substrates were polymerized together, it is assumed that surface polymers were also formed on the EG substrate. Below, the dry film thickness is reported (see Table 5).

[0270] The second polymerization initiator (BiBB) was attached to the first polymer molecule as follows: To a reaction container, DMF (186 mL), TEA (1.4 mL), DMAP (126 mg) and BiBB (12.4 mL) were added. The 1 Si-PHEMA-modified substrate and 5 EG-PHEMA-modified substrates were submersed into the solution and left to react for 10 minutes and were subsequently cleaned by sonication for 5 minutes in DCM. Subsequently, the substrates were sonicated for 10 minutes in acetone, before being left to dry in ambient conditions (ambient temperature, ambient pressure). After cleaning and dry ing, the second polymerization initiator-modified substrate (Si-PHEMA-BiBB) was analyzed by ellipsometry, and the average dry film thickness was determined and reported in Table 5.

[0271] IPTS / 128973811 1After the attachment of the second polymerization initiator to the first surface polymer molecule, a thickness increase was observed. The reaction is an acylation of the free hydroxy group in the HEMA side chain moiety. Considering one repeating unit in the surface polymer structure, this acylation would add to the molecular size of the repeating unit, hence an increase of the surface polymer molecular weight is to be expected. This was indeed observed as an increase in molecular weight would directly result in an increase in the overall thickness (in accordance with h=oMn / pNA).

[0272] The BiBB-modified substrates were exposed to a second polymer formation as follows: To a glass container (Container A), Dl-water (665 mL), Catalyst T (16 mL), MeCN (85 mL), and HEMA monomer (220 mL) were added. In a separate container (Container B) a solution of NaAsc (4000 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0273] The substrates (Si-PHEMA-BiBB and EG-PHEMA-BiBB) were placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrates were left in the reaction composition for 80 minutes and were subsequently cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrates were subjected to ellipsometry to measure the average dry film thicknesses of the formed (collapsed) surface polymer (first and second polymer molecules Si-PHEMA-BiBB-PHEMA). Below, the average dry film thickness is reported (see Table 5).

[0274] Table 5. Average dry film thickness.

[0275]

[0276] As seen from Table 5, a very thick resulting surface polymer was obtained. Thus, the method described therein can be used to generate thick surface polymers. As in Example 4, a color change was observed with the naked eye between each process step. Noteworthy, inspection of the substrates by the naked eye confirmed that changes to surface polymers took place, however, as IPTS / 128973811 1the surface polymer thickness becomes much greater than the visual light range, the surface film becomes dull and loses color. This observation was in line with the film being too thick to cause thin film interference of the visible light and was a good qualitative indicating that the film was very thick, on the level of at least 1 pm. Again, the distribution of the surface polymers appeared to be very homogeneous by visual inspection of variations in appearance.

[0277] The inventors believe that using a more hydrophilic monomer (like HEMA monomer) for the second polymerization event, a higher thickness following the second polymerization may be achieved, since the surface polymer formed is well swellable in the reaction composition used for the second polymerization event. The inventors hypothesize that while a high second polymerization initiator density may influence the overall polymerization, the steric repulsion between individual polymer chains may also influence the second polymerization event. For the present second polymerization with HEMA as second monomer, utilizing the favorable swelling of the yielded second polymer molecule, the steric repulsion may be mediated allowing for a very high surface polymer molecule film thickness.

[0278] Example 6

[0279] Preparing surface polymers having an average drv film thickness >0.5 um

[0280] The example shows the preparation of a surface polymer having an average dry film thickness above 0.5 pm and close to 1 pm.

[0281] The procedure and reaction conditions for preparing the first polymer molecule were as follows:

[0282] To a glass container (Container A), Dl-water (665 mL), MeCN (85 mL) and HEMA monomer (220 mL) and Catalyst T (16 mL) were added. In a separate container (Container B) a solution of NaAsc (4000 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A and the reaction composition was left for 5 minutes to activate the reaction composition for polymer formation.

[0283] 1 CPTMS-modified substrate (substrate Si, first polymerization initiator CPTMS), pre-cleaned as described in Example 1 and initiator-modified as described in Example 2, was placed in a reaction container and the reaction composition of container A was poured into the reaction container. The substrate was left in the reaction composition for 80 minutes and was subsequently flushed with Dl-water, then EtOH, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, IPTS / 128973811 1the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrate having first polymer molecules covalently (PHEMA) bound to the CPTMS first polymerization initiator sites was subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer of first polymer molecules (PHEMA polymer brushes). Below, the average dry film thickness is reported (see Table 6).

[0284] The second polymerization initiator (BiBB) was attached to the first polymer molecules the following way: To a reaction container, THF (200 mL), TEA (13.3 mL), and BiBB (4mL) were added. The Si-PHEMA-surface polymer molecule-modified substrate was submersed into the solution and left to react for 2 hours and was subsequently cleaned by sonication for 5 minutes in DCM. Subsequently, the substrate was flushed with Dl-water, then acetone before being sonicated for 5 minutes in acetone, and being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the second polymerization initiator-modified substrate (Si-PHEMA-BiBB) was analyzed by ellipsometry, and the dry film thickness was determined and reported in Table 6.

[0285] After the addition of the second polymerization initiator to the first surface polymer molecule, a thickness increase was observed. The BiBB-modification reaction is an acylation of the free hydroxyl group in the HEMA side chain moiety. Considering one repeating unit in the surface polymer structure, this acylation would add to the molecular size of the repeating unit, hence an increase of the surface polymer molecular weight was expected. This was indeed observed as an increase in molecular weight due to BiBB-modification results in an increase in the surface polymer thickness (in accordance with h=oMn / pNA) and confirms successful modification.

[0286] The reaction composition to form the second polymer molecule from the second polymerization initiators was prepared as follows: To a glass container (Container A), Dl-water (554mL), Catalyst T (16 mL), EtOH (340 mL), and HEMA monomer (75 mL) were added. In a separate container (Container B) a solution of NaAsc (2000 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for polymer formation.

[0287] The substrate (Si-PHEMA-BiBB) was placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrate was left in the reaction IPTS / 128973811 1composition for 80 minutes and was subsequently cleaned by sonication for 5 minutes in DI-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and dr ing, the substrate was subj ected to ellipsometry to measure the dry film thickness of the formed (collapsed) combined surface polymer (Si-PHEMA-BiBB-PGMA). Below, the average dry film thickness is reported (see Table 6).

[0288] Table 6. Average dry film thickness.

[0289]

[0290] Extraordinarily, choosing a less hydrophilic monomer (GMA) for the second polymerization than previously (HEMA in Example 5), yet more hydrophilic than MMA (Example 4) a thickness of 983.35 nm was achieved. Though swelling of the monomer in the reaction composition for forming the second polymer molecules is significantly lowered using the GMA monomer, the favored reaction conditions appear to improve on the final surface polymer thickness. The average dry film thickness of Si-PHEMA-BiBB-PGMA was measured by performing spectroscopic ellipsometry measurements at 1084 evenly distributed points across the substrate surface. The data was used to produce a thickness map as shown in Fig. 7, providing a quantitative evaluation of the surface polymer film-homogeneity. A standard deviation of 13.9 nm (-1.4% of the average dry film thickness) across all the measured points indicated excellent uniformity of the surface polymer film, confirming the robustness of the method of forming the surface polymers. Visually, a clear color change was observed after each process step (first polymerization, modification with BiBB second initiator, and second polymerization). Noteworthy, inspection of the substrates by the naked eye confirmed that changes to surface polymers took place, however, as the surface polymer thickness becomes much greater than the visible light range, the surface film becomes matt and loses its color. This observation was in line with the film being too thick to cause thin film interference of the visible light and was a good qualitative indication that the film was very’ thick, on the level of -1 pm. Furthermore, the distribution of the surface polymers appeared to be very homogeneous by visual inspection of variations in appearance. Considering the surface polymer thickness being around 1 pm and the fact that this structure consists of a first and a second polymer molecule, a standard deviation of just below 14 nm is a very minor variation.

[0291] IPTS / 128973811 1Example 7

[0292] Formation of second polymer molecule on first polymer (PGMA-OH) with second polymerization initiator

[0293] In this example, the inventors investigate the effect of increasing the number of polymer-bound initiators per square nanometer. From Example 2, a substrate with expected all available sites modified with the first polymerization initiator was prepared, and no further addition of initiators can be added this way, hence, addition of further polymerization initiators could be achieved by modifying the first polymer molecule. The polymer PGMA has an epoxide moiety in the side chains, in principle able to undergo hydrolysis which may result in a polymer molecule with 2 hydroxyl groups in each of the PGMA monomeric side chain units, however, full conversion to 2 hydroxyl groups may not be accomplished, and, thus, the PGMA polymer molecule may display a certain conversion ratio between 0 to 2 hydroxyl groups. Thus, this will in the following be envisaged as Si-PGMA-OH. In accordance herewith, the second polymerization initiator may bind to an increased number of sites (envisaged Si-PGMA-OH-BiBB), resulting in more second polymerization initiators being available for propagation with second monomeric units.

[0294] Two different polymer structures are investigated in this example: Si-PGMA-OH-BiBB-PGMA and Si-PGMA-OH-BiBB-PHEMA. For both structures, the formation of the first polymer molecule, the hydrolysis, and the formation of the second initiator, follows the same procedure. Below, the formation of the two surface polymer structures is described. Lastly, the results are discussed.

[0295] To a glass container (Container A), Catalyst M (30 mL) was added followed by Dl-water (484 mL), EtOH (410 mL) and GMA monomer (110 mL). In a separate container (Container B) a solution of NaAsc (2464 mg in 15 mL Dl-water) w as prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for polymer formation.

[0296] 14 CPTMS-modified substrates (first polymerization initiator CPTMS), pre-cleaned as described in Example 1 and initiator-modified as described in Example 2, w ere placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrates were left for 40 minutes in the reaction composition and were subsequently flushed with Dl-water, then EtOH, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the IPTS / 128973811 1substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrates having first polymer molecules ready for subsequent hydrolyzation (Si-PGMA, substrate Si) were subjected to ellipsometry to measure the dry film thickness of the formed (collapsed) surface polymer of first polymer molecules. Below, the average dry7film thickness of 14 substrate is reported (see Table 7).

[0297] To make the formation of polymer-bound second polymerization initiator BiBB possible, the epoxide of the GMA moiety was hydrolyzed to produce -OH groups as follows: To a reaction container, 35% HC1 (17 mL) was added to Dl-water (800 mL). The 14 substrates (Si-PGMA), prepared above, were placed in the reaction mixture and heated to 60°C and left for 3.5 hours. Subsequently, the substrates were immersed in Dl-water and sonicated for 5 minutes. Finally, the substates were left to dry in ambient conditions (ambient temperature, ambient pressure). After cleaning and dry ing, the substrates having first polymer molecules ready for subsequent acylation (Si-PGMA-OH) were subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer of first polymer molecules. Below, the average dry film thickness of 13 substrates (1 was removed for reference) is reported (Table 7).

[0298] The obtained Si-PGMA-OH substrates were exposed to a second polymerization initiator BiBB as follows: To a reaction container, DMF (745 mL), TEA (5.6 mL), DMAP (488.9 mg) and BiBB (49.4 mL) were added. 12 of the Si-PGMA-OH-modified substrates were submersed into the solution and left to react for 10 min, and were subsequently cleaned by rinsing with DCM, followed by sonication for 5 minutes in DCM. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions. After cleaning and drying, the modified substrates (Si-PGMA-OH-BiBB) were analyzed by ellipsometry, and the average dry film thicknesses of 12 (1 was removed for reference) substrates were determined and reported in Table 7.

[0299] After the attachment of the second polymerization initiator to the first surface molecules, a thickness increase was observed. The result of this reaction is an acylation of the free hydroxy group in the PGMA-OH side chain moiety. Considering one repeating unit in the surface polymer structure, this acylation would add to the molecular size of the repeating unit, hence, an increase of the surface polymer molecular weight was expected. This was indeed observed as an increase

[0300] IPTS / 128973811 1in molecular weight would directly result in an increase in the surface polymer thickness (in accordance with h=oMn / pNA).

[0301] The reaction composition to form the second polymer molecule (PGMA) for the first structure was prepared as follows: To a glass container (Container A), Dl-water (554 mL), Catalyst T (16 mL), EtOH (340 mL), and GMA monomer (75 mL) were added. In a separate container (Container B) a solution of NaAsc (3997 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0302] 6 substates (Si-PGMA-OH-BiBB) were placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrate was left in the reaction composition for 120 minutes and was subsequently cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrates were subjected to ellipsometry. However, the formed surface polymer structure was found to be thicker than the limitations of the ellipsometry equipment, which according to the vendor of the instrument, lies betw een 2 and 5 pm. Hence, no thickness of the surface polymer could be measured using ellipsometry, and accordingly, the thickness of the surface polymer was concluded to be at least 2 pm.

[0303] The reaction composition to form the second polymer molecule (PHEMA) for the second structure (Si-PGMA-BiBB-PHEMA) was prepared as follows: To a glass container (Container A), Dl-water (665mL), Catalyst T (16 mL), MeCN (85mL). and HEMA monomer (220 mL) were added. In a separate container (Container B) a solution of NaAsc (4003 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0304] 6 substates (Si-PGMA-OH-BiBB) were placed in a reaction container and the reaction composition of Container A w as poured into the reaction container. The substrates were left for 60 minutes and were subsequently cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrates were subjected to ellipsometry to measure the dry film thickness of the formed (collapsed) IPTS / 128973811 1combined surface polymer of first and second polymer molecules (Si-PGMA-OH-BiBB-PHEMA). However, the formed surface polymer structure was found to be thicker than the limitations of the ellipsometry instrument, which according to the vendor of the instrument, lies between 2 and 5 pm. No thickness of the surface polymer could be measured using ellipsometry, and, accordingly, the thickness of the surface polymer is expected to be at least 2 pm.

[0305] Instead of using ellipsometry, the average dry film thickness of 2 Si-PGMA-OH-BiBB-PGMA substrates and 1 Si-PGMA-OH-BiBB-PHEMA substrate was estimated using profilometry to measure the height of a step edge of the polymer film. In short, a piece of steel was used to make a small scratch in the layer of the surface polymer film, exposing the bare Si substrate beneath. The height of this step edge was then measured using a profilometer. These results are also reported in Table 7 and marked with an asterisk (*) to indicate that the thickness was obtained using profilometry and not ellipsometry

[0306] Table 7. Average dry film thicknesses and profilometry measurements.

[0307]

[0308] * Indicates surface polymer film thickness determined by means of profilometry measurements.

[0309] Amazingly, by shifting from a first polymer molecule structure with one possible modification site to one with the possibly two modification sites during formation of a second initiator, the inventors have illustrated a process in which surface polymer brush thicknesses well into the micrometer range may be achieved. Increasing the spatial density of second polymerization initiators, and, thus, achieving a high spatial density of propagating radicals is expected to lead to a large number of chain-end terminations through, e.g., radical-radical couplings. Such termination events result in “dead"’ chain ends which cannot propagate further, and as such they are detrimental to the objective of forming very thick surface polymer films. In spite of this, the method presented by the inventors in this example lead to formation of surface polymer films with thickness well above 1 pm. This is a testament to the robustness of the polymerization methodology7, as well as to the method of introducing a large number of second polymerization IPTS / 128973811 1initiators to a first surface polymer, with the purpose of forming surface polymer films with a thickness well above 1 pm. No thickness could be measured by ellipsometry’ for the Si-PGMA-OH-BiBB-PGMA and Si-PGMA-OH-BiBB-PHEMA substrate as the measurement of the dry film thickness by ellipsometry was not feasible due to the high surface polymer thickness. From the vendor of the ellipsometer instrument, it is noted that the ellipsometer used for these substrates would not be able to measure thicknesses above 2-5 pm. leading the inventors to conclude that the Si-PGMA-OH-BiBB-PGMA and Si-PGMA-OH-BiBB-PHEMA have reached a thickness of at least 2 pm when a second polymer molecule is added to the surface polymer structure. This finding was corroborated by the profilometry measurements of such substrates, where the Si-PGMA-OH-BiBB-PGMA surface polymer film was estimated to be 2895 ± 303 nm, and the Si-PGMA-OH-BiBB-PHEMA surface polymer film was estimated to be 8855 ± 727 nm.

[0310] Example 8

[0311] Si-PHEMA-BiBB-PHEMA substrate for further polymerizations from further polymerization initiators

[0312] The example shows further surface polymer formations from surface polymer of polymer molecules. One type of polymer molecules was covalently attached to the surface of the substrate, and further polymerizations are accomplished through further polymerization initiators bound to surface polymer molecules.

[0313] The reaction composition to form the first polymer molecules was prepared as follows: To a glass container (Container A), Dl-water (665 mL), MeCN (85 mL) and HEMA monomer (220 mL) and Catalyst T (16 mL) were added. In a separate container (Container B) a solution of NaAsc (4038 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation. For ease, this reaction composition was termed “Polymerization Bath”.

[0314] 7 CPTMS-modified substrates (substrate Si. first polymerization initiator CPTMA), pre-cleaned as described in Example 1, and initiator-modified as described in Example 2. were placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrates were left for 20 minutes and were subsequently flushed with Dl-water, then EtOH, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, 1 substrate having first IPTS / 128973811 1polymer molecules covalently bond to the CPTMS initiator sites (Si-PHEMA) was subjected to ellipsometry to measure the dry film thickness of the formed (collapsed) surface polymer of first polymer molecules (Si-PHEMA polymer brushes). Below, the average dry film thickness is reported (see Table 8).

[0315] Attachment of second polymerization initiator BiBB to first polymerization molecules (PHEMA) was performed as follows: To a reaction container, DMF (652mL). TEA (4.9 mL), DMAP (423 mg) and BiBB (43 mL) were added. This reaction was termed “Acylation Bath”. The remaining 6 Si-PHEMA-modified substrates were submersed into the Acrylation Bath and left to react for 10 minutes and were subsequently cleaned by sonication for 5 minutes in DCM. Subsequently, the substrates were sonicated for 10 minutes in acetone, before being left to dry in ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, 1 of the BiBB-modified substrates (Si-PHEMA-BiBB) was analyzed by ellipsometry and the dry film thickness was determined and reported in Table 8.

[0316] To form the second polymer molecule, the remaining 5 (Si-PHEMA-BiBB) substrates were immersed in to the “Polymerization Bath” and left for 20 minutes. After reaction the substrates were dipped in EtOH, sonicated in DMSO for 5 minutes, then sonicated in acetone for 5 minutes and then left to dry in ambient conditions (ambient temperature, ambient pressure). 1 substrate was withdrawn (Si-PHEMA-BiBB-PHEMA) and the dry film thickness of the formed (collapsed) combined surface polymer was analyzed using ellipsometry and reported in Table 8.

[0317] To form the third polymerization initiator attached to the polymer molecules, the 4 remaining substrates (Si-PHEMA-BiBB-PHEMA) were immersed in the “Acylation Bath” and left for 10 minutes. After reaction, the substrates (substrate Si, first polymer molecule PHEMA, second polymerization initiator BiBB, second polymer molecule PHEMA, third polymerization initiator BiBB, Si-(PHEMA-BiBB)2) were cleaned and dried as described in Example 4. 1 substrate was withdrawn and the average dry film thickness of the formed (collapsed) combined surface polymer was analyzed using ellipsometry and reported in Table 8.

[0318] The latter 2 steps (“Polymerization Bath” and “Acylation Bath”) were repeated until no more substates were left. The entire process ran in total for 5 hours. The subsequent polymeri-zations / polymerization initiator results are shown in Table 8.

[0319] IPTS / 128973811 1Beyond increasing thickness for each introduction of polymerization initiator and subsequent formation of the next surface polymer, each of the chemical conversions from surface polymer to surface polymer with polymerization initiator was verified for each step by recording Infrared Reflection Absorption Spectroscopy (IRRAS). Fig. 4 shows the IRRAS spectra for the Si-PHEMA and Si-PHEMA-BiBB substrates. For the Si-PHEMA substrate (Spectrum 1 in Fig. 4) a broad peak from 3640 cm'1to 3050 cm'1is ascribed to the O-H stretching vibration, while the peak from 3054 cm'1to 2820 cm'1is ascribed to C-H stretching vibrations. Around 1735 cm'1a sharp peak is ascribed to the C=O stretching of the carbonyl, while the peaks in the range from 1520 cm'1to 1350 cm'1are assigned to C-H bending vibrations, and the peaks in the range from 1312 cm1to 1000 cm'1are ascribed to C-0 stretching vibrations. These peaks indicate the presence of the PHEMA surface polymer. For Spectrum 2 in Fig. 4, which pertains to the Si-PHEMA-BiBB substrate, the main difference lies in the absence of the broad peak from 3050 cm'1to 3640 cm'1. The absence of this peak indicates complete conversion of the hydroxyl groups on the PHEMA surface polymer during the reaction with BiBB to obtain the Si-PHEMA-BiBB substrate. For the subsequent cycles of PHEMA surface polymer formation and subsequent reaction with BiBB to obtain initiator functionalized surface polymer, the broad peak pertaining to the O-H stretching vibration concomitantly appeared / increased and vanished / decreased in size when the next PHEMA surface polymer was added, and when the next polymer initiator (BiBB) is added, respectively. This is indicated in Fig. 5 (Spectrum 1 pertaining to Si-PHEMA-BiBB-PHEMA and Spectrum 2 pertaining to Si-PHEMA-BiBB-PHEMA-BiBB), where the O-H peak was smaller following introduction of BiBB, although it did not disappear completely, indicating that not all hydroxyl groups partake in the reaction with BiBB for the higher degrees of surface polymer structures. The same observations can be made for Si-PHEMA-BiBB-PHEMA-BiBB-PHEMA (Spectrum 1 in Fig. 6) and Si-PHEMA-BiBB-PHEMA-BiBB-PHEMA-BiBB (Spectrum 2 in Fig. 6) and Si-PHEMA-BiBB-PHEMA-BiBB-PHEMA-BiBB-PHEMA (Spectrum 3 in Fig.

[0320] 6).

[0321] IPTS / 128973811 1Table 8. Average dry film thicknesses.

[0322]

[0323] Remarkably, a higher degree surface polymer structure (formation of a fifth polymer molecule structure from polymerization initiators on polymer molecules - very large '‘macroinitiator’' formed) could be achieved from a first polymer molecule bound to a first polymerization initiator on the substrate by sequentially attaching further polymerization initiators to sequentially formed further polymer molecules. Furthermore, after 5 hours the “Polymerization Bath” showed a stable reaction kinetic profile with a stable rate for surface polymer formation, still producing a 46 nm surface polymer thickness (from a CPTMS-modified substrate), quite comparable to the thickness obtained at the beginning of the experiment (41 nm). Thus, the inventors conclude that the impressive formation of up to a fifth polymer molecule structure was not a result of, e.g., bulk polymers formed over time in solution and deposited onto the surface of the substrate but was in fact a true propagation of monomeric units, otherwise it would not be possible to prepare distinct first PHEMA polymer molecules similar to those obtained at the beginning of the experiment from a substrate only modified with CPTMS first polymerization initiators.

[0324] Noteworthy, no thickness could be reported for the Si-(PHEMA-BiBB)?-PHEMA substrate as the measurement of the dry film thickness by ellipsometry was not feasible due to the high surface polymer thickness. Again, clear color changes were observed between each process step until a thickness above 1 pm was achieved, here the substrates appeared matt. From the vendor of the ellipsometer instrument, it is noted that the ellipsometer used for these substrates would not be IPTS / 128973811 1able to measure thicknesses above 2-5 pm, leading the inventors to conclude that the Si-(PHEMA-BiBB)3-PHEMA substrate (substrate with up to fourth polymer molecules) has reached a thickness of at least 2 pm when a fourth polymer molecule is added to the surface polymer structure. Additionally, the inventors noted that the substrate Si-(PHEMA-BiBB)4 (substrate subjected to fifth polymerization initiator-modification) and Si-(PHEMA-BiBB)4-PHEMA (substrate subjected to fifth polymer molecule formation) showed some signs of the surface polymer peeling off. leaving some areas with blank Si substrate. The reason for this is not fully understood but may be a matter of optimizing reaction conditions and the way further polymer molecules form (see also below).

[0325] In a separate experimental series, the substrate produced in Example 5 (Si-PHEMA-BiBB-PHEMA) was subjected to a subsequent formation of polymer molecule-bound third polymerization initiator BiBB and a subsequent formation of third polymer molecules (third polymer molecules PHEMA) following the procedures described in Example 5 (using an 80 minutes polymerization time).

[0326] The surface polymer delaminated in some areas on the substrate. In this specific example, a lower degree combined surface polymer was obtained, however, as the starting point was a 1.248 pm Si-PHEMA-BiBB-PHEMA substrate a higher surface polymer thickness was foreseen. This observation has led the inventors to hypothesize that the stability of the surface polymer may be dependent on the grafting density of the initial polymerization initiator (first polymerization initiator), i.e., the inventors hypothesize that as the combined surface polymer structures reaches a higher degree of branching and thickness, the polymer chains in the polymer film start to experience higher steric interactions leading to at least partly delamination from the surface of the substrate. To avoid such delamination, the inventors hypothesize that starting from a lower grafting density of the first polymerization initiator, the individual polymer chains in the combined surface polymer structure gain more space which could in turn lower the possibility of high steric interactions leading to partial delamination.

[0327] Example 9

[0328] Chemical deposition of CPTMS (first polymerization initiator) and PTMS (“dummy polymerization initiator'’) to produce varying grafting densities of CPTMS

[0329] Above, the inventors hypothesize that a lower grafting density of the first polymerization initiator may improve the stability of the surface polymer following multiple polymerizations from further IPTS / 128973811 1polymerization initiators attached to the polymer molecules. In this example, a dipping procedure able to attach the first polymerization initiator (CPTMS) to a substrate was performed. Such a procedure is expected to attach as many first polymerization initiators as possible to the substrate (Si). To lower the grafting density of the first initiator molecule (i.e., CPTMS), a second nonpolymerization initiator (PTMS = phenyltrimethoxysilane, “dummy polymerization initiator”) was added with CPTMS in a certain ratio. Thus, to achieve different grafting densities of CPTMS, varying amounts of PTMS relative to CPTMS were used. To investigate the effect of a varying CPTMS grafting density on the surface polymer formation, PMMA polymers were polymerized from the first polymerization initiators.

[0330] Attachment of first polymerization initiators / ”dummy polymerization initiators” was performed as follows: 16 silicon wafer (Si) substrates, pre-cleaned as described in Example 1, were used for surface initiator-modification with CPTMS first polymerization initiators and PTMS as “dummy polymerization initiators” using a chemical dipping method. In a reaction container, 1000 mL of toluene, 10 mL of acetic acid. CPTMS and PTMS (see Table 9) were added and stirred with a spatula. 4 substrates were added to each of the solutions (1:1, 1:50, 1:75, and 1:100) and left to react. After 30 minutes, the substrates were removed from the solution, dipped 5 times in acetone and then transferred to a separate bath with acetone and sonicated for 1 minute. After sonication, the substrates were removed from the solution and left to dry for 2 minutes at ambient conditions (ambient temperature, ambient pressure) before being transferred to an oven at 80°C for 15 minutes. The substrates were withdrawn from the oven and left for 24 hours at ambient conditions (ambient temperature, ambient pressure).

[0331] Table 9. Molar ratios of CPTMS versus PTMS.

[0332]

[0333] The first polymer molecule (PMMA) formed on substrates were performed as follows:

[0334] To a glass container (Container A), Dl-water (484 mL), Catalyst T (16 mL), EtOH (410 mL). and MMA monomer (75 mL) were added. In a separate container (Container B) a solution of NaAsc (4000 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into IPTS / 128973811 1Container A. and the reaction composition was left for 5 minutes to activate the reaction composition for polymer formation.

[0335] The 16 CPTMS first polymerization initiator-modified substates (substrates with varying density of CPTMS first polymerization initiators, Table 9), were placed in a reaction container and the reaction composition of Container A was poured into the reaction container (polymer formation of substrates from 1: 1 CPTMS :PTMS ratio were formed in a separate bath under similar conditions). The substrates were left in the reaction composition and withdrawn at different times (5, 10, 20 and 40 minutes, 1 substrate from each of the molar ratios in Table 9). In this way, the rate of surface polymer formation was evaluated as a function of time. The “rate'’ of surface polymer formation in the reaction composition is referred to as the thickness (in nm) of surface polymers formed as a function of time. After withdrawal of a substrate from the reaction composition, the substrate was cleaned by sonication for 5 minutes in Dl-water. Subsequently the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, each substrate was subjected to ellipsometry to measure the dry film thickness of the formed (collapsed) surface polymer of the first polymer molecules (Si-PMMA). Below, the average dry film thickness is reported (see Table 10).

[0336] Table 10. Polymerization time and corresponding thickness for PMMA surface polymer formed on Si wafer substrates with varying density of surface initiator.

[0337]

[0338] Interestingly, the formation of PMMA as first polymer molecule on substrates with a first polymerization initiator made with a CPTMS:PTMS molar ratio of 1:75, proceeded in a linear fashion (see Fig. 9) in the initial 20 minutes. At this first polymerization initiator density, the formation of the first polymer molecule was assumed less hindered, possibly resulting in favorable conditions for polymer formation. Notably, for the first 20 minutes of the polymer forming reaction, the thickness of first polymer molecules (PMMA) on the substrate made with first polymerization initiators in a 1:75 ratio of CPTMS:PTMS were lower than the thickness of first IPTS / 128973811 1polymer molecules (PMMA) on substrate with higher grafting density of CPMTS, such as 1:50 and 1:1 ratio of CPTMS:PTMS. However, after 40 minutes the thickness of the surface polymer on these three substrates reached a comparable thickness having regard to standard deviations. This could be due to fewer polymer molecules yet longer molecules forming on the substrate with a 1:75 CPTMS:PTMS ratio following longer polymerization times. At much lower first polymerization initiator densities (1:100), fewer polymerization initiators appeared to be available for surface polymer formation, and accordingly, no significant thickness was added to final surface polymer thickness. This finding was in agreement with the perception described above in the detailed description that there is a limit to the obtainable length of a surface polymer. Based on the similar thickness obtained via very different kinetic pathways after 40 minutes polymerization time in case of the 1:1 and 1:75 CPTMS / PTMS molar ratios, respectively, differences in chain lengths for the surface polymers formed on the two substrates (1 : 1 substrate and 1:75 substrate) were expected. Thus, the 1:75 CPTMS / PTMS substrate was assumed to have fewer but longer polymer molecules compared to the 1 : 1 CPTMS / PTMS substrate. Based on these finding the inventors hypothesize that grafting density of first polymerization initiators may¬ influence the chain length of, and the free volume around, the first polymer molecules, which mayin turn also impact the properties such as thickness and stability' of more complex surface polymers formed in subsequent polymerization events to add, e.g., second, third, fourth, etc. polymer molecules.

[0339] Example 10

[0340] Surface polymer from first polymerization initiator layer being a layer of CPTMS polymerization initiator and PTMS “dummy” initiator

[0341] The example shows the preparation of a surface polymer by controlling the grafting density of the first polymerization initiator and, thus, the formation of first polymerization molecules. The first polymerization initiators were CPTMS, the first polymer molecule PHEMA, the second polymerization initiator BiBB, and the second polymer molecule PHEMA. For the surface polymer formation, a low-activity- -highly -living reaction composition was chosen to ensure a better resolution of the polymer molecule grafting densities, and, thus, observe the effect of controlling grafting density-.

[0342] The first polymer molecules were formed on the substrates in the following manner:

[0343] IPTS / 128973811 1Catalyst T was mixed as follows: In a vial, 0.18 mL CuCh solution (34.1 mg CuCh in 90 mL DI-water), 8.82 mL Dl-water, 0.14 mL TPMA in ethanol (84.3 mg TPMA dissolved in 7 mL EtOH by sonication for 5 minutes in sonicator) and 9.86 mL EtOH.

[0344] To a glass container (Container A), Catalyst T (19 mL) was added 0.6 M carbonate buffer (330 mL), EtOH (155 mL) and HEMA monomer (150 mL) followed by addition of Dl-water (330 mL). Buffer was added to control pH of the reaction composition during the surface polymer formation. In a separate container (Container B) a solution of NaAsc 4002 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A and the reaction composition was left for 2 minutes to activate the reaction composition for surface polymer formation. Then, the pH was adjusted to pH 8.8 by adding concentrated H2SO4 (0.6 mL) to optimize the thickness of formed surface polymers.

[0345] 4 first polymerization initiator-modified substrates (Si wafers, CPTMS) were used, and these were denoted Vapor ref 1, 2, 3 and 4, respectively. The substrates were pre-cleaned as described in Example 1 and polymerization initiator-modified as described in Example 2 and Example 4. 5 other Si-substrates were modified with a mixture of first polymerization initiators (CPTMS) and first “dummy” polymerization initiators (PTMS) in a certain ratio (CPTMS / TPMS 1:1, 1:50, 1:75, 1:100 and 1:200) and denoted 1:1, 1:50, 1:75, 1:100 and 1:200. These substrates were pre-cleaned as described in Example 1 and first polymerization initiator-modified as described in Example 9. All substrates were placed in a reaction container and the reaction composition of Container A was poured into the reaction container 5 minutes after the addition of Container B to Container A and adjustment of pH. The substrates were left for 40 minutes to form first polymer molecules and were subsequently recovered from the reaction composition, flushed in Dl-water, then sonicated 5 minutes in Dl-water, flushed with Dl-water, and then sonicated for 5 minutes in acetone, before being left to dry at ambient pressure and temperature. The reaction composition was sealed after recovering of the substrates and was reused for formation of the second polymer molecule. After cleaning and drying, the substrates were subjected to ellipsometry to measure the average dry film thickness of the formed surface polymer of first polymer molecules (PHEMA polymer brushes).

[0346] Below, the average dry film thickness is reported (see Table 11). As seen from Table 11, the average dry film thicknesses of the formed first polymer molecules were reduced in conformity with the grafting density of the first polymerization initiators (effect of presence of “dummy” first polymerization initiators on substrates 1:1, 1:50, 1:75, 1:100, and 1:200). The reference substrates IPTS / 128973811 1(with only CPTMS first polymerization initiator, substrates Vapor ref 1, Vapor ref 2, Vapor ref 3, and Vapor ref 4) had all comparable PHEMA first polymer molecules atached. The substrates having reduced density of first polymerization initiators (substrates 1:1, 1:50, 1:75, 1: 100, and 1:200) all had a lower average dry film thickness as compared to the reference substrates Vapor ref 1, Vapor ref 2, Vapor ref 3 and Vapor ref 4.

[0347] The obtained substrates were exposed to a second polymerization initiator, BiBB. according to the following procedure: To a reaction container, DMAP (611.3 mg) was dissolved in DMF (931 mL). TEA (7.3 mL) was then added followed by BiBB (62mL). The Si-PHEMA-modified substrates were submersed into the solution and left to react for 10 minutes to introduce the second polymerization initiator BiBB. After the reaction, the substrates were flushed with acetone followed by sonication in DCM for 5 minutes. Subsequently, the substrates were flushed in acetone then sonicated in acetone for 5 minutes, before being left to dry in ambient conditions (ambient pressure and ambient temperature). After cleaning and drying, the BiBB-modified substrates (Si-PHEMA-BiBB) were analyzed by ellipsometry, and the average dry film thicknesses were determined and reported in Table 11. As expected, adding the second polymerization initiator, BiBB, to the surface polymer increased the average dry film thickness as the reaction with BiBB is an acylation of the free hydroxy group in the HEMA side chain moiety7.

[0348] Polymer formation from the second polymerization initiators was performed by reusing the reaction composition from the first polymer formation and submerge the Si-PHEMA-BiBB substrates (Vapor ref 1, Vapor ref 2, Vapor ref 3, Vapor ref 4, 1:1, 1:50, 1:75, 1:100, and 1:200) into the reaction composition for 40 minutes. Following the polymerization the substrates were flushed in Dl-water, then sonicated in Dl-water for 5 minutes, before being flushed with acetone and then sonicated in acetone for 5 minutes, before being left to dry7at ambient pressure and temperature. The substrates were then analyzed by ellipsometry. The average dry film thickness following the second polymerization is reported in Table 11 below. The increase in average dry7film thickness between the first and second polymerizations are indicated in the column "‘Thickness gain (%)?’. As can be seen from Table 11. the thickness gain among the reference substrates (Vapor ref 1, Vapor ref 2, Vapor ref 3, and Vapor ref 4) is essentially the same, whereas the thickness gain in respect of substrates 1:1, 1:50, 1:75, 1:100, and 1:200 is correlated to the number of possible BiBB-modification sites on PHEMA (OH groups available for acylation by BiBB) (possible more second polymer molecule side chain propagation) as well as corresponding less steric hindrance during the polymer propagation of the second polymer molecules from the IPTS / 128973811 1BiBB initiator (possible longer second polymer molecules propagated from the fewer BiBB polymerization initiator sites).

[0349] Table 11. Average dry film thicknesses following first polymerization, BiBB-modification, and second polymerization.

[0350]

[0351] Example 11

[0352] Surface polymer from second polymerization initiator polymerization, where the second initiator is a mixture of BiBB polymerization initiator and AcBr “dummy’7initiator

[0353] This example illustrates reducing the number of BiBB second polymerization initiator sites by cografting BiBB polymerization initiator with a non-polymerization (“dummy”) initiator, AcBr.

[0354] Firstly, 6 CPTMS -modified substrates (Si substrates, pre-cleaned according to Example 1. and modified with first polymerization initiator CPTMS according to Example 2). The 6 substrates were denoted Sil (200), Si2 (150), Si3 (100), Si4 (75), Si5 (50), and Si 6 (25). The number “200” indicates that a ratio of BiBB:AcBr of 1:200 was used. The number “150” indicates that a ratio of BiBB: AcBr of 1:150 was used. The number “100” indicates that a ratio of BiBB: AcBr of 1:100 was used. The number “75” indicates that a ratio of BiBB: AcBr of 1:75 was used. The number “50” indicates that a ratio of BiBB: AcBr of 1 :50 was used. The number “25” indicates that a ratio of BiBB: AcBr of 1:25 was used.

[0355] IPTS / 128973811 1The reaction composition for forming first polymer molecules from CPTMS first polymerization initiator sites was prepared as follows:

[0356] Catalyst T2.1: 79.9 mg TPMA and 7 mL EtOH were mixed in Container X and sonicated for 5 minutes. 0.18 mL of a solution of 1513.9 mg CuCb in 1000 mL Dl-water, and 8.82 mL Dl-water were mixed in Container Y. 0.14 mL of Container X was added to Container Y followed by 9.86 mL EtOH.

[0357] To a glass container (Container A), Catalyst T2.1 (19 mL) was added 0.6 M carbonate buffer (330 mL), EtOH (155 mL) and HEMA monomer (150 mL) followed by 330 mL Dl-water. In a separate container (Container B) a solution of NaAsc (4002 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 3 minutes to activate the ligand and catalyst for surface polymer formation. After 3 minutes, 400 pL concentrated H2SO4 was added to Container A under stirring to adjust the pH to 8.8 to optimize surface polymer formation.

[0358] 2 minutes following addition of H2SO4, the 6 CPTMS-modified substrates were placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrates were left for 20 minutes to form surface polymers from the CPTMS first polymerization initiators. Following polymerization, the substates were recovered and dipped in Dl-water, then sonicated in Dl-water for 5 minutes, before being flushed by acetone, and then sonicated for 5 minutes in acetone. Subsequently, the substrates were left to dry in ambient conditions (ambient pressure and ambient temperature). After cleaning and drying, the substrates having first polymer molecules covalently bound to the CPTMS initiator sites (Si-PHEMA) were subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer of first polymer molecules (PHEMA polymer brushes). Below, the average dry film thickness is reported in Table 13.

[0359] The obtained polymer molecule-modified substrates were exposed to a second polymerization initiator (BiBB). To vary the grafting density of the BiBB initiator, BiBB was mixed with AcBr in certain ratios (see Table 12). For preparing the correct mixture of BiBB and AcBr, the following solutions were prepared and mixed as described in Table 12:

[0360] IPTS / 128973811 1Solution I: DMF (10 mL), DMAP (310 mg), and EtsN (3.65 mL).

[0361] Solution II: DMF (31 mL). and BiBB (0.39 mL).

[0362] Solution III: DMF (309 mL) and AcBr (11.44 mL).

[0363] Table 12. Ratio between the second polymerization initiator, BiBB, and the second nonpolymerization (“‘dummy”) initiator, AcBr.

[0364]

[0365] For each initiator-modification solution (see Table 12), 1 Si-PHEMA polymer molecule-modified substrate was submersed into the solution and left to react for 10 minutes. The substrate was subsequently cleaned by sonication for 5 minutes in DCM. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry' at ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, the second polymerization initiator-modified substrates (Si-PHEMA-BiBB) were analyzed by ellipsometry, and the average dry film thickness was determined and reported in Table 13.

[0366] As expected, the addition of the second polymerization initiator (BiBB) and dummy initiator (AcBr) led to an average dry film thickness increase. As can be seen from Table 13, no matter the ratio between BiBB and AcBr, the surface polymer (Si-PHEMA-BiBB / AcBr) of each of the substrates Sil (200), Si2 (150), Si3 (100), Si4 (75), Si5 (50) and Si7 (25) all had comparable average dry film thicknesses. The inventors hypothesize that the small size of the AcBr molecule, relative to the that of the BiBB, may lead to a higher degree of acetyl moieties (Ac) in the surface polymer, thereby accounting for the comparable average dry film thickness.

[0367] Second polymer molecules were formed from the second polymerization initiators (BiBB) as follows:

[0368] Catalyst T2.2 was prepared of: 79.9 mg TPMA and 7 mL EtOH were mixed in Container X and sonicated for 5 minutes. 0.18 mL of a solution of 1513.9 mg CuCh in 1000 mL Dl-water, and 8.82

[0369] IPTS / 128973811 1mL DI- water was mixed in Container Y. 0.14 mL of Container X was added to Container Y followed by 9.86 mL EtOH.

[0370] The reaction composition for forming surface polymers was prepared as described above in respect of the formation of the first polymer molecules, however, with Catalyst T2.2 instead of Catalyst T2.1. The reaction composition additionally consisted of carbonate buffer, EtOH, HEMA monomer, and Dl-water. which were mixed, and activator. NaAsc, was added 3 minutes before polymerization to activate the ligand. Concentrated H2SO4 was added to optimize the surface polymer formation rate, and after 2 minutes the BiBB-modified substrates were immersed in the reaction composition and left 20 minutes to form second polymer molecules from the BiBB-initiator sites. From the AcBr '‘dummy” initiator sites, no second polymer molecules are propagated. The substrates were recovered and dipped in Dl-water, then sonicated in Dl-water for 5 minutes, being flushed with acetone, and sonicated for 5 minutes in acetone. Subsequently, the substrates were left to dry in ambient conditions (ambient temperature and ambient pressure). The substrates were analyzed by ellipsometry’ to measure the average dry film thickness of the formed combined surface polymer (Si-PHEMA-BiBB / AcBr-PHEMA). Below, the average dry film thicknesses are reported in Table 13. The last column in Table 13 is a calculation of the percentage increase (“thickness gain”) in average dry film thicknesses between the Si-PHEMA substrates and the Si-PHEMA-BiBB / AcBr-PHEMA substrates.

[0371] Table 13. Average dry film thicknesses. Si-PHEMA substrates are formed from CPTMS-modified Si substrates.

[0372]

[0373] IPTS / 128973811 1As can be seen from Table 13. AcBr as dummy initiator was able to “dilute"’ the presence of the polymerization initiator BiBB. The more the BiBB-initiator was diluted, the lower average dry film thickness was obtained. The inventors hypothesize that the formed second polymer molecules chains may be longer the more diluted the BiBB second polymerization initiator becomes, possible due to spatial / steric reasons.

[0374] Example 12

[0375] Cleaning procedure for Eagle Glass substrates

[0376]

[0377] Eagle glass substrates 100x100x0.7 mm, 2-side polished, were cut into 4 sheets of 50x50x0.7 mm substrates. The EG substrates were placed in a wafer carrier in a vertical orientation and washed by dipping in iPrOH to remove any adsorbed dust particles and other residues. The substrates were then air-dried in ambient pressure and ambient temperature for at least 2 minutes. Following drying, the substrates were immersed in 5M NaOH solution at a temperature of 60°C and sonicated for 10 minutes in the sonicator. The substrates were then washed by dipping in Dl-water followed by 5-minute sonication in the sonicator in fresh Dl-water. Following sonication, the substrates were dipped in iPrOH followed by 5-minute sonication in the sonicator in fresh iPrOH. Finally, the substrates were dried in the oven at 80°C for 15 minutes.

[0378] Example 13

[0379] Surface polymers (Si-PHEMA-BiBB-PFIEA) having an average drv film thickness >0.5 urn The example shows the preparation of a surface polymer composed of first polymer molecules, PHEMA. and second polymer molecules, PHEA, the surface polymer having an average dry film thickness above 0.5 pm and close to 1 pm.

[0380] The catalyst for the polymerizations was prepared as follows: 0.14 mL TPMA solution (83.8 mg TPMA in 7 mL HEMA) was mixed with 6.86 mL HEMA to prepare 7 mL of dilute TPMA solution. 0.18 mL CuCb solution (1.5 g CuCh 2H2O dissolved in 1000 mL) was mixed in 8.82 mL Dl-water to prepare 9 mL of dilute CuCb solution. Finally, the diluted 7 mL TPMA solution and the diluted 9 mL CuCh solution were mixed to form 16 mL of diluted catalyst solution.

[0381] In a glass container (Container A), 0.6 M carbonate buffer (330 mL), Dl-water (330 mL) and HEMA monomer (308 mL) were mixed. The diluted catalyst solution (16 mL) was added. In a separate container (Container B) a solution of NaAsc (4000 mg in 15 mL Dl-water) was prepared. IPTS / 128973811 1The content of Container B was poured into Container A and left for 5 minutes to activate the reaction composition for surface polymer formation. Then, the pH of the polymerization was adjusted to 8.8 using H2SO4to control the thickness of formed surface polymers.

[0382] 2 CPTMS-modified substrates (substrate Si wafer, first polymerization initiator CPTMS), precleaned as described in Example 1, and 12 CPTMS-modified substrates (substrate EG glass, first polymerization initiator CPTMS), pre-cleaned as described in Example 12. Both types of substrates were CPTMS-modified as described in Example 2. The substrates were placed in a reaction container in a substrate holder and the reaction composition of container A was poured into the reaction container. The substrates were left to react for 60 minutes and were subsequently recovered from the reaction composition and dipped in Dl-water before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). Following drying, the Si substrates having first polymer molecules covalently (PHEMA) bound to the CPTMS initiator sites were subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer of first polymer molecules (PHEMA polymer brushes). Below, the average dry film thickness is reported (Table 15).

[0383] The second polymerization initiator (BiBB) was attached to the first polymer molecules the following way: To a reaction container, DMF (931 mL), TEA (7.3 mL), and DMAP (611 mg) were mixed and sonicated to dissolve the DMAP. Then, BiBB (62 mL) was added and the solution stirred. The solution was poured into a reaction container.

[0384] The EG-PHEMA and Si-PHEMA-surface polymer molecule-modified substrates (in a substrate holder) were submersed into the solution and left for 10 minutes and were subsequently cleaned by sonication for 5 minutes in DCM. Subsequently, the substrates were sonicated for 5 minutes in DCM, followed by flushing with acetone, before being sonicated in acetone for 5 minutes. The substrates were left to dry in ambient conditions (ambient pressure and ambient temperature). 1 Si-substrate with second polymerization initiators (BiBB) was analyzed by ellipsometry, and the dry film thickness determined. The average dry thickness is reported in Table 15.

[0385] After the addition of the second polymerization initiator (BiBB) to the first polymer molecule (PHEMA), a thickness increase was observed. The BiBB-modification is an acylation of the free hydroxyl group in the HEMA side chain moiety. Considering one repeating unit in the surface IPTS / 128973811 1polymer structure, this acylation would add to the molecular size of the repeating unit, hence an increase of the surface polymer molecular weight is to be expected. This was indeed observed for the present results as an increase in molecular weight would directly result in an increase in the surface polymer thickness (in accordance with h=oMn / pNA) and confirmed successful BiBB-modification. Reaction of PHEMA surface polymers with the second polymerization initiator (BiBB) also resulted in an increase in water contact angle (reported in Table 16) which also confirmed the installation of the second polymerization initiator (BiBB). The increase in WCA was expected as the -OH functionalities in PHEMA backbone are being converted to an ester.

[0386] Formation of the second polymer molecule was performed in the following manner: A catalyst solution was prepared of 83.8 mg TPMA. dissolved in 7 mL HEA by sonication. Thereto, 9 mL CuCh solution (1.5 g CuCh • 2H2O dissolved in 1000 mL) was added.

[0387] To a glass container (Container A), 0.6 M carbonate buffer (330 mL), Dl-water (330 mL) and HEA monomer (305 mL) were mixed. The catalyst (16 mL) was added. In a separate container (Container B) a solution of NaAsc (4001 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes. Then, the pH of the polymerization was adjusted to 8.8 using H2SO4 to optimize surface polymer formation conditions.

[0388] The 2 Si-PHEMA-BiBB and 12 EG-PHEMA-BiBB substrates were placed in a reaction container in a substrate holder and the reaction composition of container A (the reaction composition) was poured into the reaction container. The substrates were left for 40 minutes and were subsequently dipped in Dl-water and then sonicated in Dl-water for 5 minutes. Subsequently, the substrates were flushed with acetone then sonicated for 5 minutes in acetone, before being left to dry in ambient conditions (ambient temperature and ambient pressure). The formation of Si-PHEMA-BiBB-PHEA (PHEMA first polymer molecules, PHEA second polymer molecules) was confirmed by an increase in the average dry film thickness, measured by ellipsometry. In addition, the formation of Si-PHEMA-BiBB-PHEA was further confirmed by a significant decrease in the WCA compared to Si-PHEMA-BiBB (reported in Table 16) upon second polymerization with HEA monomer. Such a decrease in WCA was expected with the installation of -OH functionalities upon formation of PHEA sidechains. Since ellipsometry is not suited for glass substrates, the Si substrates were used as indicator for successful formation of a surface polymer also on the EG substrates. Below, the average dry film thickness of the 2 Si substrates is reported (Table 15). The IPTS / 128973811 1water contact angles (WCA) of the surface polymer (PHEMA-BiBB-PHEA) formed on a single Si and a single EG substrates are very’ similar (reported in Table 16), confirming the successful formation of same surface polymer on both types of substrates.

[0389] Table 15. Average dry film thickness.

[0390]

[0391] Table 16. Water contact angle on glass substrates with surface polymers.

[0392]

[0393] Example 14

[0394] Surface polymers composed of PHEMA as first polymer molecule and PSt as second polymer molecule

[0395] In this example, the preparation of a surface polymer composed of PHEMA and poly(styrene) (PSt) is shown.

[0396] The first polymer molecule was prepared as follows:

[0397] The catalyst was prepared by dissolving TPMA (81.2 mg) in 7 mL HEMA by sonication for 2 minutes, and adding 9 mL of a solution of 1.5 g CUCI2 2H2O in 1 L Dl-water.

[0398] To a glass container (Container A), HEMA (310 mL), Dl-water (330 mL), and 0.6M carbonate buffer (330 mL of a solution of 688 g NaHCCh, 85.9 g Na2COs in 13.5 L Dl-water) and catalyst (16 mL) as prepared above were added. In a separate container (Container B) a solution of NaAsc (4002 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A. pH was adjusted to pH 8.8 by adding concentrated H2SO4 (0.4 mL) to optimize reaction conditions.

[0399] IPTS / 128973811 1The reaction composition of Container A was poured into the reaction container 5 minutes after addition of concentrated H2SO4. 14 CPTMS-modified substrate (substrate Si, first polymerization initiator CPTMS), initiator-modified as described in Example 2, were placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrates were left in the reaction composition for 40 minutes and were subsequently flushed with Dl-water. before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, the substrate having first polymer molecules covalently bond to the CPTMS initiator sites (Si-PHEMA) was subjected to ellipsometry (45 points measured) to measure the average dry film thickness of the formed (collapsed) surface polymer. Below, the average dry film thickness of 1 substrate is reported (see Table 17). As all substrates were subjected to the same reaction conditions, the 1 substrate was considered indicative of comparable formation of surface polymers on the other substrates.

[0400] The second polymerization initiator (BiBB) was attached to the first polymer molecule as follows: To a reaction container, DMF (931 mL), TEA (7.3 mL) and DMAP (613 mg) were mixed and sonicated until DMAP was fully dissolved. Then, BiBB (62 mL) was added. The 14 Si-PHEMA-modified substrates were submersed into the solution and left to react for 10 minutes and were subsequently cleaned by dipping in DCM. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry in ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, 1 second polymerization initiator-modified substrate (Si-PHEMA-BiBB) was analyzed by ellipsometry, and the average dry film thickness of 1 substrate is reported in Table 17. As all substrates were subjected to the same reaction conditions, the 1 substrate was considered indicative of comparable formation of surface polymers on the other substrates.

[0401] After the attachment of the second polymerization initiator to the first surface polymer molecule, a thickness increase was observed. The yield of this reaction is an acylation of the free hydroxy group in the HEMA side chain moiety. Considering one repeating unit in the surface polymer structure, this acylation would add to the molecular size of the repeating unit, hence an increase of the surface polymer molecular weight is to be expected. This was indeed observed as an increase in molecular weight would directly result in an increase in the overall average dry film thickness (in accordance with h=oMn / pNA).

[0402] IPTS / 128973811 1Formation of second polymer molecules from BiBB-modified second polymerization initiator sites:

[0403] To a glass container (Container A), Dl-water (460 mL), Catalyst M (30 mL), EtOH (480 mL), and styrene monomer (5 mL) were added. In a separate container (Container B) a solution of NaAsc (4002 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition.

[0404] 2 of the 14 substrates (Si-PHEMA-BiBB) were placed in a reaction container and the content of Container A was poured into the reaction container. The remaining substrates were used for other experiments. The substrates were left in the reaction composition for 30 minutes and were subsequently cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, 1 substrate was subjected to ellipsometry to measure the average dry film thicknesses of the formed (collapsed) surface polymer (first and second polymer molecules Si-PHEMA-BiBB-PHEMA). Below, the average dry7film thickness is reported (see Table 17).

[0405] Table 17. Average dry film thickness of 1 substrate following first and second polymerizations.

[0406]

[0407] As seen from Table 17 more than a 100 percent increase was achieved by the second polymerization.

[0408] Example 15

[0409] Surface polymers with PHEMA as first polymer molecule and a random-copolymer as second polymer molecule

[0410] In this example, a surface polymer of PHEMA (first polymer molecule) and random copolymer of PHEMA and either of PBuMA, PBnzMA, and PEHMA, respectively, is shown. The surface polymer comprises a random copolymer of HEMA and BuMA, HEMA and BnzMA, or HEMA IPTS / 128973811 1and EHMA, respectively, as second polymer molecules. The second polymerization was performed using the two monomers in different mol% ratios. Substrates SI. S2, S3, S4, and S5 were used to grow a surface polymer of PHEMA (first polymer molecule) and random copolymer of PHEMA and either of PBuMA, PBnzMA, and PEHMA, respectively in different mol% (second polymer molecule), and substrates S6, S7, S8, and S9 were used as controls for first surface polymer molecule formation.

[0411] The reaction composition for forming the first polymer molecule (PHEMA) on substrates SI to S9 was prepared as follows:

[0412] The catalyst was prepared by dissolving TPMA (82.2 mg) in 7 mL HEMA by sonication for 2 minutes, and adding 9 mL of a solution of 1.5 g CuCh-2H2O in 1 L Dl-water.

[0413] To a glass container (Container A), HEMA (310 mL), Dl-water (330 mL), 330 mL 0.6M carbonate buffer (prepared of 688 g NaHCOs, and 85.9 g Na2CO? in 13.5 L Dl-water) and 16 mL Catalyst as prepared above were added. In a separate container (Container B) a solution of NaAsc (4002 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0414] 9 CPTMS-modified substrates (substrate Si, first polymerization initiator CPTMS), initiator-modified as described in Example 2, were placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrates were left for 40 minutes and were subsequently flushed with Dl-water, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, a substrate having first polymer molecules covalently bond to the CPTMS initiator sites (Si-PHEMA) was subjected to ellipsometry (45 points measured) to measure the average dry’ film thickness of the formed (collapsed) surface polymer of first polymer molecules. Below, the average dry' film thickness is reported (see Table 18).

[0415] The second polymerization initiator (BiBB) was attached to the first polymer molecule on substrates SI to S9 as follows: To a reaction container. DMF (931 mL), TEA (7.3 mL) and DMAP (613 mg) were mixed and sonicated until DMAP was fully dissolved. Lastly, BiBB (62 mL) were IPTS / 128973811 1added. The 9 Si-PHEMA-modified substrates were submersed into the solution and left to react for 10 minutes and were subsequently cleaned by dipping in DCM. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry in ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, the second polymerization initiator-modified substrates (Si-PHEMA-BiBB) were analyzed by ellipsometry , and the average dry film thickness was determined and reported in Table 18.

[0416] Table 18. Average dry film thicknesses of following polymerization with HEMA monomer and modification with second initiator BiBB, respectively.

[0417]

[0418] As can be seen from Table 18, after the attachment of the second polymerization initiator to the first surface polymer molecule, an increase in average dry film thickness was observed. This was expected as the BiBB initiator is incorporated into the free hydroxy group in the HEMA side chain moiety by acylation.

[0419] Reaction composition for second polymer molecule formation on substrate SI (85 mol% HEMA.

[0420] 15 mol% tBuMA): The catalyst was prepared by dissolving TPMA (85.4 mg) in 7 mL HEMA by sonication for 2 minutes and adding 9 mL of a solution of 1.5 g CuCk 2H2O in 1 L Dl-water. The activator for the catalyst was prepared by dissolving NaASc (4000 mg in 15 mL Dl-water) in DI-water using a vortex. To a glass container (Container A), HEMA monomer (26.75 mL), BuMA monomer (6.2 mL), Dl-water (42.5 mL). EtOH (20 mL), and catalyst (1.9 mL). were added. Then 1.5 mL of activator solution was added to the reaction mixture in container A and the reaction was left for 5 minutes. The substrate, SI (Si-PHEMA-BiBB), was placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrate was IPTS / 128973811 1left for 40 minutes and was subsequently cleaned by first dipping in Dl-water, then sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, the substrate was subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer (Si-PHEMA-BiBB-(PHEMA85-co-PBuMA15). Below, the average dry film thickness is reported (see Table 19).

[0421] Reaction composition for second surface polymer molecule formation on substrate S2 (70 mol% HEMA, 30 mol& tBuMA): The catalyst was prepared by dissolving TPMA (85.4 mg) in 7 mL HEMA by sonication for 2 minutes, and a CuCh solution was added (9 mL of a solution of 1.5 g CuCb 2H2O in 1 L Dl-water). The activator was prepared by dissolving NaASc (4000 mg in 15 mL Dl-water) in Dl-water using a vortex. To a glass container (Container A), HEMA monomer (22 mL), BuMA monomer (12.5 mL), Dl-water (35 mL), EtOH (33 mL), and catalyst (1.9 mL) were added. Then 1.5 mL of activator solution was added to Container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation. Substrate S2 was placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrate was left for 40 minutes and was subsequently cleaned by first dipping in Dl-water, then sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrate was subjected to ellipsometry to measure the average dry film thicknesses of the formed (collapsed) surface polymer (first and second polymer molecules Si-PHEMA-BiBB-(PHEMA70-co-PBuMA30). Below, the average dry' film thickness is reported (see Table 19).

[0422] Reaction composition for second surface polymer molecule formation on substrate S3 (85 mol% HEMA, 15 mol% BnzMA): The catalyst was prepared by dissolving TPMA (85.4 mg) in 7 mL HEMA by sonication for 2 minutes, and a CuCb solution was added (9 mL of a solution of 1.5 g CuCb 2H2O in 1 L Dl-water). The activator was prepared by dissolving NaASc (4000 mg in 15 mL Dl-water) in Dl-water using a vortex. To a glass container (Container A). HEMA monomer (26.75 mL), benzyl methacrylate (BnzMA) monomer (6.6 mL), Dl-water (40 mL), EtOH (27.5 mL), and catalyst (1.9 mL) were added. Then 1.5 mL of activator solution was added to Container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation. Substrate S3 was placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrate was left for 40 IPTS / 128973811 1minutes and was subsequently cleaned by first dipping in Dl-water, then sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrate was subjected to ellipsometry to measure the average dry film thicknesses of the formed (collapsed) surface polymer (first and second polymer molecules Si-PHEMA-BiBB-(PHEMA85-co-PBnzMA15). Below, the average dry film thickness is reported (see Table 19).

[0423] Reaction composition for second surface polymer molecule formation on substrate S4 (70 mol% HEMA. 30 mol% BnzMA): The catalyst was prepared by dissolving TPMA (85.4 mg) in 7 mL HEMA by sonication for 2 minutes, and a CuCh solution was added (9 mL of a solution of 1.5 g CuCh 2H2O in 1 L Dl-water). The activator was prepared by dissolving NaASc (4000 mg in 15 mL Dl-water) in Dl-water using a vortex. To a glass container (Container A), HEMA monomer (22 mL), BnzMA monomer (13.2 mL), Dl-water (30 mL), EtOH (40 mL), and catalyst (1.9 mL) were added. Then 1.5 mL of activator solution was added to the reaction composition in container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation. Substrate S4 was placed in a reaction container and the reaction composition of of Container A was poured into the reaction container. The substrate was left for 40 minutes and was subsequently cleaned by first dipping in Dl-water, then sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrate was subjected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer (first and second polymer molecules Si-PHEMA-BiBB-(PHEMA70-co-PBnzMA30). Below, the average dry film thickness is reported (see Table 19).

[0424] Reaction composition for second surface polymer molecule formation on substrate S5 (85 mol% HEMA. 15 mol% EHMA): The catalyst was prepared by dissolving TPMA (85.4 mg) in 7 mL HEMA by sonication for 2 minutes, and a CuCh solution was added (9 mL of a solution of 1.5 g CuCh 2H2O in 1 L Dl-water). The activator was prepared by dissolving NaASc (4000 mg in 15 mL Dl-water) in Dl-water using a vortex. To a glass container (Container A). HEMA monomer (26.75 mL), 2-ethylhexyl methacrylate (EHMA) monomer (8.7 mL), Dl-water (30 mL), i-PrOH (32 mL), and Catalyst (1.9 mL) were added. Then 1.5 mL of activator solution was added to the reaction composition in container A and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation. Substrate S5 was placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The IPTS / 128973811 1substrate was left for 40 minutes and was subsequently cleaned by first dipping in Dl-water, then sonication for 5 minutes in Dl-water. Subsequently, the substrate was sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature, ambient pressure). After cleaning and drying, the substrate was subj ected to ellipsometry to measure the average dry film thickness of the formed (collapsed) surface polymer (first and second polymer molecules Si- PHEMA-BiBB-(PHEMA85-co-PEHMA15). Below, the average dry film thickness is reported (see Table 19).

[0425] Table 19. Average dry film thickness of substrates SI, S2, S3, S4 and S5. The numbers following the polymerized monomers indicate the starting mol% rations of the two monomers used for forming the random co-block polymers.

[0426]

[0427] As seen from Table 19, the average dry film thickness increased by more than 1,000 percent between the first (PHEMA) polymerization (see Table 18) and second polymerizations. A color change of the substrate was observed with the naked eye between each process step. Noteworthy, inspection of the substrates by the naked eye confirmed that changes to surface polymers took place, however, as the surface polymer thickness becomes much greater than the visual light range, the surface film becomes dull and loses color. This observation is in line with the film being too thick to cause thin film interference of the visible light and is a good qualitative indicating that the film is very thick, on the level of at least 1 pm. The distnbution of the surface polymers appeared to be very homogeneous by visual inspection of variations in appearance. These findings are in agreement with the ellipsometry data.

[0428] IPTS / 128973811 1In Table 20, the water contact angles (WCA) of substrates SI to S5 (post second polymerization), are reported along with their PHEMA analogue (PHEMA-BiBB-PHEMA, obtained in another experiment), i.e., no copolymer formation. In all cases, the WCA was higher than their PHEMA analogue (PHEMA-BiBB-PHEMA). This was in agreement with a HEMA unit having one -OH functionality, whereas the copolymerized monomer has not. Thus, the WCAs determined confirmed the incorporation of repeat units of the copolymerized monomer. In addition. WCA was also seen to increase with increasing content of each co-monomer, confirming larger incorporation of repeat units corresponding to the copolymerized monomer.

[0429] Table 20. Water contact angle (WCA) of substrates SI to S5 (post second polymerization). The PHEMA-BiBB-PHEMA is included as a reference and was obtained from another experiment.

[0430]

[0431] Substrates SI to S5 (post second polymerization) were further analyzed by FT-IR spectroscopy. The three important characteristics that were used to analyze the FT-IR spectra are following, (i) HEMA unit displays an -OH functionality while the three co-monomers used do not, (ii) relative content of -CH2- units are different for each monomer, and (iii) all four monomers display one -C=O unit. Therefore, copolymerization of HEMA with any of the three co-monomers used in this experiment will affect the relative intensities (relative to HEMA homopolymer) of the peaks corresponding to -CH2- stretching (2790-3050 cm'1) and -OH stretching (3050-3780 cm'1) but not the relative intensity of the -C=O stretching (1650-1800 cm'1). In addition, the overall intensity (intensity7of each peak) of any of the FT-IR spectra also depends on the average dry7film thickness of the surface polymer film and number density of the repeat units per unit volume of the surface polymer film (the larger the size of a repeat unit is, the lesser the number density will be). Therefore, the FT-IR spectra of the substrates SI to S5 (post second polymerization) and PHEMA-BiBB-PHEMA were normalized with respect to the -C=O stretching peak to a value of 1 to

[0432] IPTS / 128973811 1deconvolute the effect of thickness of the surface polymer film and co-monomer size on the relative intensities of the -CH2- stretching and the -OH stretching.

[0433] The analysis of the FT-IR spectra was performed by comparing the relative intensities of three areas corresponding to -C=O stretching (1650-1800 cm’1), -CH2- stretching (2790-3050 cm’1) and -OH stretching (3050-3780 cm’1) as shown in Fig. 13, Fig. 14, and Fig. 15.

[0434] Fig. 13 shows overlayed FT-IR spectra of PHEMA-BiBB-PHEMA (substrate from a previous experiment), PHEMA-BiBB-(PHEMA85-co-PBuMA15) (substrate SI) and PHEMA-BiBB-(PHEMA70-co-PBuMA30) (substrate S2). Due to the chemical structure of n-BuMA, a repeat unit within the surface polymer corresponding to n-BuMA does not display any -OH functionality but displays a larger amount of -CH2- repeat units as compared to a repeat unit of HEMA. Thus, incorporation of n-BuMA along the PHEMA backbone during polymerization was expected to reduce the peak intensity corresponding to -OH stretching while it was expected to observe an increase in the peak intensity corresponding to -CH2- stretching. Therefore, the reduced peak intensity corresponding to -OH stretching and increased peak intensity corresponding to -CH2-stretching in PHEMA-BiBB-(PHEMA85-co-PBuMA15) (substrate SI) compared to PHEMA-BiBB-PHEMA, shown in Fig. 13, confirms the incorporation of both PBuMA and PHEMA along the backbone of the second polymer molecule. This effect was more pronounced in the case of PHEMA-BiBB-(PHEMA70-co-PBuMA30) (substrate S2) where the intensity of -OH stretching reduced and the intensity of the -CH2- stretching increased further compared to PHEMA-BiBB-(PHEMA85-co-PBuMA15) (substrate SI) as shown in Fig. 13, confirming increased incorporation of PBuMA along the second polymer molecules. Thus, it was concluded that the formation of a random copolymer of PHEMA and PBuMA was successful. The current method used in analyzing the FT-IR spectra cannot quantify the absolute incorporation of the comonomers in the second polymer molecules. Therefore, using, e.g., 85% HEMA monomer as compared to 15% BuMA monomers does not necessarily imply that the second polymer molecule of the resulting surface polymer is composed of 85% HEMA repeat units and 15% BuMA monomers. The inventors believe it will be possible to arrive at more quantitative ways of characterizing the repeat unit composition.

[0435] Fig. 14 shows an overlayed FT-IR spectra of PHEMA-BiBB-PHEMA (substrate from another experiment), PHEMA-BiBB-(PHEMA85-co-PBnzMA15) (substrate S3) and PHEMA-BiBB-(PHEMA70-co-PBnzMA30) (substrate S4). A repeat unit corresponding to BnzMA does not IPTS / 128973811 1contain any -OH functionality and display lesser amount of -CH2- repeat units as compared to a repeat unit of HEMA. As a result, the incorporation of BnzMA along the second polymer molecule was expected to reduce the peak intensity corresponding to both -OH and -CH2- stretchings. Therefore, the reduced peak intensity corresponding to -OH and -CH2- stretching in PHEMA-BiBB-(PHEMA85-co-PBnzMA15) (substrate S3) compared to PHEMA-BiBB-PHEMA confirmed the incorporation of both PBnzMA and PHEMA along the backbone of the second polymer molecule. This effect was more pronounced in the case of PHEMA-BiBB-(PHEMA70-co-PBnzMA30) (substrate S4) where the intensity of -OH and -CH2- stretchings reduced further compared to PHEMA-BiBB-(PHEMA85-co-PBnzMA15) (substrate S3) as shown in Fig. 14, confirming increased incorporation of PBnzMA along the backbone of second polymer molecule. However, the current method used in analyzing the FT-IR spectra cannot quantify the absolute incorporation of the comonomers along the PHEMA backbone. Therefore, using, e.g., 85% HEMA monomer as compared to 15% BnzMA monomers in the polymerization mixture does not necessarily imply that the second polymer molecule of the resulting surface polymer is composed of 85% HEMA repeat units and 15% BnzMA monomers. The inventors believe it will be possible to arrive at more quantitative ways of characterizing the repeat unit composition.

[0436] Fig. 15 shows an overlayed FT-IR spectra of PHEMA-BiBB-PHEMA (substrate from another experiment), and PHEMA-BiBB-(PHEMA85-co-PEHMA15) (substrate S5). A repeat unit corresponding to EHMA does not contain any -OH functionality but contains larger amount of -CH2- units compared to a repeat unit corresponding to HEMA. As a result, the incorporation of EHMA along the backbone of second polymer molecules was expected to reduce the peak intensity corresponding to -OH, and increase the peak intensity corresponding to -CH2- stretching. Therefore, the slight reduction of the peak intensity corresponding to -OH stretching and an increase in the peak intensity corresponding to -CH2- stretching (Fig. 16, an enhancement of the Fig. 15) observed for PHEMA-BiBB-(PHEMA85-co-PEHMA15) compared to PHEMA-BiBB-PHEMA, confirmed the successful incorporation of PEHMA along the second polymer backbone. Minor changes were observed as compared to the changes observed in the case of random copolymers with BuMA and BnzMA, respectively, possibly indicating a reduced incorporation of EHMA repeat units as compared to BuMA and BnzMA repeat units. It is hypothesized that the larger size of the EHMA monomer compared to the HEMA monomer could be the reason for reduced incorporation. Another explanation could also be that polymerization conditions were less optimized.

[0437] IPTS / 128973811 1Example 16

[0438] Surface polymers composed of PSt as first polymer molecule and PHEMA as second polymer molecule

[0439] In this example, a surface polymer composed of (poly (styrene) (PSt)) as first polymer (backbone polymer) and PHEMA as second polymer molecule is shown.

[0440] The reaction composition for forming the first polymer molecule was prepared as follows:

[0441] To a glass container (Container A), Catalyst M (45 mL) was added followed by Dl-water (690 mL), EtOH (96%, 720 mL) and styrene monomer (7.5 mL). In a separate container (Container B) a solution of NaAsc (6.0 g in 22.5 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for surface polymer formation.

[0442] 10 CPTMS -modified substrates (substrate Si, initiator-modified with CPTMS as described in Example 2) were placed in a reaction container and the content of Container A was poured into the reaction container. The substrates were left for 80 minutes and were subsequently flushed with Dl-water, before being withdrawn from the reaction composition and cleaned by sonication for 5 minutes in Dl-water, followed by sonication for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, one substrate having first polymer molecules covalently bond to the CPTMS initiator sites (Si-PSt) was subjected to ellipsometry (10 points measured) to measure the average dry film thickness of the formed (collapsed) surface polymer. Below, the average dry film thickness (see Table 21) and WCA (see Table 22) of one substrate is shown.

[0443] A Si-PSt substrate, prepared above, was modified by installation of chloromethyl (CM) moieties. The remaining 9 Si-PSt substrates were saved for later experiments. The CM moiety will act as the second polymerization initiator in subsequent polymerizations. Installation of the CM moiety was performed as follows: To a glass container, paraformaldehyde (1.2 g), DCM (40 mL), and trimethylsilyl chloride (TMS-C1, 2.6 mL) were added in the mentioned order, and the solution was sonicated for 10 seconds. Then, tin(IV)chloride (SnCh, 1.2 mL) was added. One Si-PSt substrate (prepared as stated above) was added. The glass container was equipped with a reflux condenser, and the solution was heated to 45°C for 4 hours. Subsequently, the substrate was cleaned by washing with acetone, then Dl-water, then EtOH, and air-dried by N2 gas under ambient conditions IPTS / 128973811 1(ambient temperature and ambient pressure). After cleaning and drying, the second polymerization initiator-modified substrate (Si-PSt-CM) was analyzed by ellipsometry (see Table 21) and WCA (see Table 22). After the CM-modification, an average dry film thickness increase was observed confirming a decoration of existing phenyl groups of PSt with CM moieties through electrophilic aromatic substitution. The chloromethylation adds to the molecular size of a repeating unit, hence an increase of the surface polymer molecular weight was expected. This was indeed observed. Theoretically, an increase in molecular weight directly result in an increase in the overall average dry film thickness in accordance with the formula h =oMn'pNA.

[0444] The reaction composition for the second polymer (PHEMA) formation was prepared as follows: The catalyst was prepared by dissolving TPMA (16.8 mg) in 1.4 mL HEMA by sonication for 2 minutes and adding 1.8 mL of a solution of 1.5 gCuCh -2H2O in 1 L Dl-water. To aglass container (Container A), HEMA (61.6 mL), Dl-water (66 mL), and 0.6 M carbonate buffer (66 mL of a solution of 688 g NaHCCh, 85.9 g Na2CCh in 13.5 L Dl-water) and catalyst (3.2 mL) as prepared above were added. In a separate container (Container B) a solution of NaAsc (800 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for polymer formation. Then, the pH of the polymerization was adjusted to 8.8 using concentrated H2SO4to optimize the surface polymer formation conditions.

[0445] The second polymerization initiator-modified substrate (Si-PSt-CM as prepared above), as well as a non-modified reference substrate (Si-PSt as prepared above) were placed in a reaction container and the reaction composition of Container A was poured into the reaction container. The substrates were left for 10 minutes and were subsequently flushed with Dl-water, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). After cleaning and dry ing, both substrates (of which only one were modified with CM moieties prior to the second polymer formation) were subjected to ellipsometry’ (45 points measured) to measure the average dry film thickness of the formed (collapsed) surface polymer. Below, the average dry film thicknesses (see Table 21) and WCA (see Table 22) are reported.

[0446] IPTS / 128973811 1Table 21. Average dry film thickness of 1 substrate following first and second polymerizations.

[0447]

[0448] As seen from Table 21, a significant thickness increase (approximately 300 percent) was achieved by the second polymerization (of the Si-PSt-CM substrate). In comparison, the reference Si-PSt substrate (no second polymerization initiator) had no significant thickness changes after the second polymerization (Si-PSt-P2) with HEMA monomer, confirming no polymerization took place - as expected. A distinct color change of the Si-PSt-CM substrate after the second polymerization (formation of Si-PSt-CM-PHEMA) was observed with the naked eye (from brown to blue with a red shade). No color change was observed for the Si-PSt-P2 substrate after the second polymerization (no second polymerization initiator), visually confirming no polymerization took place. The visual findings were confirmed by ellipsometry (see Table 21).

[0449] Table 22. Water contact angle on glass substrates with surface polymers.

[0450]

[0451] As seen from Table 22, chloromethylation led to significant increase in WCA, confirming the modification with the hydrophobic chloromethyl groups, expected to increase WCA. After formation of the second polymer (Si-PSt-CM-PHEMA, a WCA typical for PHEMA surface polymers (57 °) was obtained. In comparison, the reference Si-PSt-P2 (no second polymerization initiator) substrate exhibited a WCA of 77 after the second polymerization, which w as higher than typically observed for PHEMA surface polymers, and, thus, confirmed that no polymerization took place.

[0452] Transmission infrared spectroscopy (IR) w as employed to further confirm the formation of Si-PSt- CM-PHEMA surface polymers. Fig. 17 shows overlayed spectra of Si-PSt, Si-PSt-CM, Si-PSt-P2

[0453] IPTS / 128973811 1and Si-PSt-CM-PHEMA. The conversion of Si-PSt to Si-PSt-CM is observed by a splitting of peaks in the 1500 cm-1 region, indicating at least a partial conversion of the PSt phenyl groups to a substituted equivalent (chloromethyl substituents). The successful polymerization of Si-PSt-CM to yield Si-PSt-CM-PHEMA was observed by intense signals characteristic of PHEMA in the 3400 cm-1 region (O-H stretch), 2800-3000 cm-1 region (sp3C-H stretch region) and 1720 cm-1 region (C=O stretch region). For comparison, the Si-PSt-P2 spectrum was identical to the Si-PSt spectrum, confirming that the second polymer formation (PHEMA) only occurred when the Si-PSt substrate was modified by CM moieties prior to the second polymer formation, and confirming that the CM moieties acted as second polymerization initiator in the second polymerization.

[0454] Example 17

[0455] Surface polymers composed of PHEMA as first polymer molecule and varying density of the second PHEMA polymer

[0456] The reaction composition for forming the first polymer molecule was prepared as follows:

[0457] The catalyst was prepared by dissolving TPMA (84.2 mg) in 7 mL HEMA by sonication for 5 minutes and adding 9 mL of a solution of 1.5 g CuCh 2H2O in 1 L Dl-water.

[0458] To a glass container (Container A), HEMA (310 mL), Dl-water (330 mL), and 0.6M carbonate buffer (330 mL of a solution of 688 g NaHCCh, 85.9 g Na2COs in 13.5 L Dl-water) and catalyst (16 mL) as prepared above were added. In a separate container (Container B) a solution of NaAsc (3999.4 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A. and the reaction composition was left for five minutes to activate the reaction composition for polymerization. pH was adjusted to pH 8.8 by adding concentrated H2SO4 (0.4 mL) to optimize the reaction conditions. 9 CPTMS-modified substrates (S 1 to S9) (substrate Si, first polymerization initiator CPTMS, initiator-modification was performed as described in Example 2) were placed in the reaction container containing the activated reaction composition. The substrates were left for 40 minutes and were subsequently flushed with Dl-water, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were flushed with acetone and then sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, the substrate having first polymer molecules covalently bond to the CPTMS initiator sites (Si-PHEMA) was subjected to

[0459] IPTS / 128973811 1ellipsometry (45 points measured) to measure the average dry film thickness of the formed (collapsed) surface polymer. The dry film thicknesses of the substrates are reported in Table 24.

[0460] The second polymerization initiator (BiBB) was attached to the first polymer molecule as follows: The first PHEMA polymer molecule was modified either with the polymerization initiator (BiBB) or both the polymerization initiator (BiBB) and a “dummy” initiator (acetyl bromide = AcBr) in varied molar ratios. In all cases the total molar concentration of polymerization initiator and dummy initiator (BiBB + AcBr) was kept constant. The reason for varying the density of the polymerization initiator (BiBB) was to vary the density' of the second polymer molecules protruding from the first polymer molecule.

[0461] Three solutions were made and denoted “BiBB”, “AcBr” and “DMAP / Et3N” firstly prepared:

[0462] “BiBB” was prepared by mixing 12.8mL BiBB and 116mL DMF.

[0463] “AcBr” was prepared by mixing 17.3mL AcBf in 156mL DMF.

[0464] “DMAP / E13N” was prepared by mixing 306.7mg 4-dimethylaminopyridine (DMAP), 3.65mL tri ethylamine (Et3N) and lOmL DMF.

[0465] Different amounts of “BiBB” and “AcBr” added to separate containers carry ing the same quantity of "DM AP / Et3N” while keeping the total molar amount of “BiBB” and "AcBr’ ’ constant. The total volume of the solutions was adjusted to the same volume by adding different amounts of DMF to keep the total molar concentration of the polymerization initiator and dummy initiator (BiBB and AcBr) constant for all three solutions. A detailed description is presented in Table 23.

[0466] Table 23. Second polymerization initiator mixtures.

[0467]

[0468] The prepared solutions were poured into separate containers carrying 1 Si-PHEMA surface polymer molecule-modified substrate (SI to S9). The substrates were left for 10 minutes. IPTS / 128973811 1Subsequently, the substrates were sonicated for 5 minutes in DCM, followed by flushing with acetone, before being sonicated in acetone for 5 minutes. The substrates were left to dry at ambient conditions (ambient pressure and ambient temperature).

[0469] All the substrates (post modification) were analyzed by ellipsometry, and the dry film thickness are presented in Table 24. A thickness increase was observed for all the substrates. The BiBB / AcBr-modification is an acylation of the free hydroxyl group in the HEMA side chain moiety. Considering one repeating unit in the surface polymer structure, this acylation would add to the molecular size of the repeating unit, hence an increase of the surface polymer molecular weight is to be expected. This was indeed observed for the present results as an increase in molecular weight would directly result in an increase in the surface polymer thickness (in accordance with h=oMn / pNA) and confirmed successful modification.

[0470] Formation of the second polymer molecule was performed as follow s:

[0471] A TPMA solution was prepared of 84.5 mg TPMA, dissolved in 7 mL EtOH by sonication. A catalyst solution was then prepared by adding 0.18 mL CuCk solution (1.5 g CuCb 2H2O dissolved in 1000 mL), H2O (8.82 mL), 0.14 mL TPMA solution and 9.86 mL EtOH.

[0472] To a glass container (Container A), 0.6 M carbonate buffer (330 mL of a solution of 688 g NaHCOs. 85.9 g Na2COs in 13.5 L Dl-water), Dl-water (330 mL), HEMA monomer (150 mL), EtOH (155 mL) and catalyst (19 mL) as prepared above were added.

[0473] In a separate container (Container B) a solution of NaAsc (4003.7 mg in 15 mL Dl-water) was prepared. The content of Container B was poured into Container A, and the reaction composition was left for 5 minutes to activate the reaction composition for polymerization. pH w as adjusted to pH 8.8 by adding concentrated H2SO4 (0.4 mL) to optimize the reaction conditions. The activated, pH-adjusted reaction composition was poured into a separate container (Container C). The substrate holder carrying the 9 Si-PHEMA-BiBB substrates (SI to S9) was immersed in the reaction container (Container C), containing the activated reaction composition. The substrates were left for 20 minutes and w ere subsequently flushed with Dl-water, before being cleaned by sonication for 5 minutes in Dl-water. Subsequently, the substrates were flushed with acetone and then sonicated for 5 minutes in acetone, before being left to dry at ambient conditions (ambient temperature and ambient pressure). After cleaning and drying, the substrates were subjected to

[0474] IPTS / 128973811 1ellipsometry (45 points measured) to measure the average dry film thickness of the formed (collapsed) surface polymer. The dry film thicknesses of the substrates are reported in Table 24. Table 24. Surface polymer formations, “w.r.t” means "‘with respect to".

[0475]

[0476] The substrates exhibited an increasing final thickness (following second polymer molecule thickness) as a function of increasing BiBB mol%. The percentage increase in thickness (second polymer molecule thickness) compared to the thickness of the first polymer molecule was significantly higher at 10 mol% BiBB compared to the rest, z.e., from 10 to 100 mol% BiBB. The plot (Fig. 18), representing a percentage increase in thickness (second polymer molecule thickness) against BiBB mol%, exhibits a non-linear behavior (thickness profile). The inventors hypothesize that this is correlated to a higher probability of chain-termination events with an increase in BiBB mol%.

[0477] Example 18

[0478] Nanoindentation

[0479] Nanoindentation experiments were performed on an EG-PHEMA-BiBB-PHEA substrate from Example 13 and an EG-PHEMA-BiBB-PHEMA substrate from Example 5 to measure Young’s modulus of the surface-polymer coating. The average dry' thicknesses of the surface-polymer coatings, shown in Table 25, are measured on reference substrates on Si-substrates (as the average dry film thickness cannot be measured by ellipsometry on a glass substrate). The Si-substrates

[0480] IPTS / 128973811 1were polymerized together with the glass substrates, and were, thus, subjected to same polymerization conditions.

[0481] Nano-indentation experiments were performed with an Anton Paar UNHT3nanoindenter, using a Berkovich tip. The ultra-high resolution UNHT3nanoindenter is designed to examine nanomechanical properties of materials, including soft polymeric thin films. The nanoindentation experiments were performed using a trapezoidal load function which consists of a linear loading regime, a hold regime at the highest load and an unloading regime. The indenter was loaded to a maximum load of 30 pN at a loading rate of 180 pN / minute, held at the maximum load for five seconds to minimize creep effect, and then unloaded at a rate of 180 pN / minute as shown in Fig.

[0482] 12. All the indentations were carried out in ambient conditions (30% relative humidity and 21.9 °C). The nanoindenter was calibrated by indenting against fused quartz as the standard reference sample.

[0483] Ten indentations were performed on EG-PHEMA-BiBB-PHEMA at one location. In comparison, fifteen indentations were performed over three locations (five indentations at each location) on EG-PHEMA-BiBB-PHEA. The average indentation depths at a maximum load of 30 pN were 95.7 ± 12.2 nm for EG-PHEMA-BiBB-PHEMA, and 161.6 ± 8.3 nm for EG-PHEMA-BiBB-PHEA as shown in Fig. 19 and Table 25. Nanoindentation of EG-PHEMA-BiBB-PHEA yielded nearly a twofold larger indentation depth for a given applied force (30 pN) compared to EG-PHEMA-BiBB-PHEMA. Such difference in stiffness clearly demonstrates the improved softness gained with EG-PHEMA-BiBB-PHEA compared EG-PHEMA-BiBB-PHEMA, and, thus, surface polymers may be designed to display certain properties.

[0484] In Table 25, the instrumented modulus from the EG-PHEMA-BiBB-PHEA and EG-PHEMA-BiBB-PHEMA is reported. As not to be confused with the elastic modulus, the instrumented modulus gives a very close approximation, while being subject to calibration and test conditions. With that in mind, two tests carried out on the same machine with the same test procedure will yield I-to-1 comparable results, as in the case of EG-PHEMA-BiBB-PHEA and EG-PHEMA-BiBB-PHEMA.

[0485] IPTS / 128973811 1Table 25. Nanoindentation data.

[0486]

[0487] * As measured on a corresponding Si substrate.

[0488] ** Tg value obtained from literature respectively for PHEMA bulk polymer and PHEA bulk polymer.

[0489] The force-indentation curves (Fig. 19) were further used to determine the Instrumented Modulus of the substrates. The Instrumented modulus (Eit) of EG-PHEMA-BiBB-PHEA was measured to be 0.973 ± 0.04 GPa, and 2.781 ± 0.435 for EG-PHEMA-BiBB-PHEMA, see Table 25. Based on the reported glass transition temperatures (Tg) of PHEA and PHEMA (bulk polymer, not actual surface polymer), it may reasonably be assumed that, at normal ambient temperature, PHEMA second polymer molecules (formed via second polymerization) of the surface polymer EG-PHEMA-BiBB-PHEMA are “frozen” in their place due to restricted bond rotation while PHEA second polymer molecules (formed via second polymerization) of the EG-PHEMA-BiBB-PHEA surface polymer retain at least some mobility, however, the impact in the case of surface polymers as shown in Table 25 was unknown as bulk polymers and surface polymers cannot readily be compared. However, from Table 25, it appears that even with the same “inner” surface polymer (PHEMA), major changes in properties occurred when introducing the outer PHEA surface polymer instead of PHEMA. The low Instrumented modulus (Eit) of the two surface polymer fdms (see Table 25) confirmed that a property changes indeed occurred. The lower Instrument modulus of the EG-PHEMA-BiBB-PHEA indicates that this surface polymer film is softer and more rubbery than EG-PHEMA-BiBB-PHEMA. Thus, in some applications, EG-PHEMA-BiBB-PHEA may be an excellent choice for a stress accommodating layer. Furthermore, the lower instrumented hardness (modulus) of EG-PHEMA-BiBB-PHEA as compared to EG-PHEMA-BiBB-PHEMA also demonstrate a significant aptitude for plastic deformation.

[0490] IPTS / 128973811 1

Claims

Claims1. A substrate having a surface polymer on a surface of the substrate, the surface polymer comprising:first polymer molecules covalently bonded to first polymerization initiation sites on the surface of the substrate; andsecond polymer molecules covalently bonded to second polymerization initiation sites on the first polymer molecules;wherein the average dry film thickness of the surface polymer is at least 0.5 pm.

2. A substrate having a surface polymer on a surface of the substrate, the surface polymer comprising:first polymer molecules covalently bonded to first polymerization initiation sites on the surface of the substrate;second polymer molecules covalently bonded to second polymerization initiation sites on the first polymer molecules;wherein the first polymer molecules, and / or the second polymer molecules comprise copolymers.

3. A substrate according to claim 1 or 2, further comprising third polymer molecules covalently- bonded to at least third polymerization initiator sites on the second polymer molecules.

4. A substrate according to claim 3, wherein third polymer molecules are bonded covalently to some first polymerization initiator sites and / or some second polymerization initiator sites.

5. A substrate according to any one of claims 1-3, further comprising fourth polymer molecules covalently bonded to at least fourth polymerization initiator sites on the third polymer molecules.

6. A substrate according to claim 5, wherein the fourth polymer molecules are bonded covalently to some first polymerization sites, some second polymerization initiator sites, and / or some third polymerization sites.

7. A substrate according to claim 2, wherein the average dry film thickness of the surface polymer is at least 0.5 pm.IPTS / 128973811 18. A substrate according to any one of claims 1-7, wherein the average dry film thickness of the surface polymer is at least 1 pm.

9. A substrate according to any one of claims 1-8, wherein a ratio of the first polymerization initiators on the surface of the substrate to non-polymerizing initiator sites on the surface of the substrate is controlled within a certain range.

10. A substrate according to claim 8 or 9, wherein the ratio of first polymerization initiators to non-polymerizing initiator sites on the surface ofthe substrate is 1:

1. 1:25, 1:40, 1:50, 1:75, 1:100, or 1:200.

11. A substrate according to any one of claims 1-10, wherein each of the first polymerization initiator; the second polymerization initiator; the third polymerization initiator; and the fourth polymerization initiator independently is selected from 2-bromoisobutyryl bromide (BiBB), p-(chloromethyl)phenyltrimethoxy silane (CPTMS), and chloromethyl (CM) moiety.

12. A substrate according to any one of claims 1-11, wherein each of the first polymer molecule; the second polymer molecule; the third polymer molecule; and the fourth polymer molecule independently is selected from poly(2-hydroxyethyl methacrylate) (PHEMA), poly(glycidyl methacrylate) (PGMA), poly(n-butyl methacrylate) (PBuMA), poly(tert-butyl methacrylate) (PtBMA), poly(benzyl methacrylate) (PBnzMA), poly(2-ethylhexyl methacrylate) (PEHMA), poly(2-hydroxylethyl acrylate) (PHEA), and polystyrene (PSt), or a combination thereof.

13. A substrate according to claim 12, wherein each of the first polymer molecule, the second polymer molecule, the third polymer molecule, and the fourth polymer molecule independently are copolymers.

14. A substrate according to claim 12, wherein the first polymer molecule is poly(2 -hydroxy ethyl methacrylate) (PHEMA) or polystyrene (PSt).

15. A substrate according to claim 13, wherein the second polymer molecule is a copolymer of poly(2-hydroxy ethyl methacrylate) (PHEMA) and poly(benzyl methacrylate) (PBnzMA). poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(n-butyl methacrylate) (PBuMA), poly(2- IPTS / 128973811 1hydroxyethyl methacrylate) (PHEMA) and poly(2-ethylhexyl methacrylate) (PEHMA), poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl acrylate (PHEA), or polyphydroxy ethyl methacrylate) (PHEMA) and polystyrene (PSt).

16. A surface polymer formed on a surface of a substrate by:providing a substrate;exposing the substrate to a first polymerization initiator;exposing the substrate to a first monomer;exposing the substrate to a second polymerization initiator; andexposing the substrate to a second monomer.

17. A surface polymer according to claim 16, further comprising:exposing the substrate to a third polymerization initiator; andexposing the substrate to a third monomer.

18. A surface polymer according to claim 16 or 17, further comprising:exposing the substrate to a fourth polymerization initiator; andexposing the substrate to a fourth monomer.

19. A surface polymer formed on a surface of a substrate by:exposing a substrate to first polymerization initiators covalently binding to a surface of the substrate;exposing the substrate to a first monomer to form first polymer molecules from the first polymerization initiator sites;exposing the substrate to second polymerization initiators covalently binding to the first polymer molecule; andexposing the substrate to a second monomer to form second polymer molecules from at least the second polymerization initiator sites.

20. A surface polymer according to claim 19, further comprising:exposing the substrate to third polymerization initiators covalently binding to at least the second polymer molecules; andexposing the substrate to a third monomer to form third polymer molecules from at least the third polymerization initiator sites.IPTS / 128973811 121. A surface polymer according to claim 19 or 20, further comprising:exposing the substrate to fourth polymerization initiators covalently binding to at least the third polymer molecules; andexposing the substrate to a third monomer to form fourth polymer molecules from at least the fourth polymerization initiator sites.

22. A surface polymer according to any one of claims 19-21, wherein one or more of the surface polymer molecules are copolymers.

23. A surface polymer according to any one of claims 16-22. wherein the surface polymer molecules formed on the substrate have an average dry film thickness of at least 0.5 pm.

24. A surface polymer according to any one of claims 16-22, wherein the polymer molecules formed on the substrate have an average dry film thickness of at least 1 pm.

25. A surface polymer according to any one of claims 1 -24, wherein each of the first monomer, the second monomer, the third monomer, and the fourth monomer independently is comprised in a reaction composition comprising:a catalyst;a ligand;an activator; anda solvent.

26. A surface polymer according to claim 25, wherein the catalyst is obtained from Cu, Fe or Ru.

27. A surface polymer according to claim 25, wherein the ligand is selected fromN,N,N’,N'’,N”,-pentamethyldiethylene-triamine (PMDETA), tris[2-(dimethylamino)ethyl]amine (MeeTREN), tris(2-aminoethyl)amine (TREN), tris(2-pyridylmethyl)amine (TPMA). 1.1.4.7.10,10-hexa-methyltriethylenetetramine (HMTETA), tetramethylethylenediamine (TMEDA), 1, 4, 8, 11 -tetramethyl- 1,4, 8,11-tetraazacyclotetradecane (Me-iCyclam). and / or 2,2’-bipyridyl (BiPy).IPTS / 128973811 128. A surface polymer according to claim 25, wherein the activator is selected from sodium ascorbate (NaAsc). ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose, glucose with GOx, and / or pyrogallic acid.

29. A surface polymer according to any one of claims 25-28, further comprising a buffer.

30. A surface polymer according to any one of claims 25-29, wherein the reaction composition further comprises a halogen salt.

31. A surface polymer according to any one of claims 25-30, wherein the reaction composition further comprises a surfactant.

32. A surface polymer according to any one of claims 25-31, wherein the reaction composition further comprises a polyquatemium compound.

33. A surface polymer according to any one of claims 16-24, wherein each of the first polymerization initiator; the second polymerization initiator; the third polymerization initiator; and the fourth polymerization initiator independently is selected from 2-bromoisobutyryl bromide (BiBB),p-(chloromethyl)phenyltrimethoxy silane (CPTMS), and chloromethyl (CM) moiety.

34. A surface polymer according to any one of claim 16-33, wherein each of the first monomer; the second monomer; the third monomer; and the fourth monomer independently is selected from 2 -hydroxyethyl methacrylate (HEMA), and glycidyl methacry late (GMA).

35. A surface polymer according to any one of claims 16-34, wherein a ratio of the first polymerization initiators on the surface of the substrate to non-polymerizing initiator sites on the surface of the substrate is controlled within a certain range.

36. A surface polymer according to claim 35, wherein the ratio is controlled by converting a portion of the first polymerization initiators to non-polymerizing initiators.

37. A surface polymer according to claim 34 or 35 wherein the ratio of first polymerization initiators to non-polymerizing initiator sites on the surface ofthe substrate is 1:1, 1:25, 1:40, 1:50, 1:75, 1:100, or 1:200.IPTS / 128973811 138. A method for forming a surface polymer of polymer molecules on a substrate, comprising: providing a substrate;exposing the substrate to a first polymerization initiator;exposing the substrate to a first monomer;exposing the substrate to a second polymerization initiator; andexposing the substrate to second monomer.

39. A method according to claim 38 further comprising:exposing the substrate to a third polymerization initiator; andexposing the substrate to a third monomer.

40. A method according to claim 38 or 39, further comprising:exposing the substrate to a fourth polymerization initiator; andexposing the substrate to a fourth monomer.

41. A method for forming a surface polymer of polymer molecules on a substrate, comprising:providing a substrate having first polymerization initiators covalently bound to a surface of the substrate;exposing the substrate to a reaction composition comprising a first monomer to form first polymer molecules covalently bound to first polymerization initiator sites;exposing the substrate to a second polymerization initiator covalently binding to the first polymer molecules; andexposing the substrate to a second monomer to form second polymer molecules covalently bound to the first polymer molecules.

42. A method according to claim 41, further comprising:exposing the substrate to third polymerization initiators covalently binding to at least the second polymer molecules; andexposing the substrate to a third monomer to form third polymer molecules from at least the third polymerization initiator sites.

43. A method according to claim 41 or 42 further comprising:IPTS / 128973811 1exposing the substrate to fourth polymerization initiators covalently binding to at least the third polymer molecules; andexposing the substrate to a third monomer to form fourth polymer molecules from at least the fourth polymerization initiator sites.

44. A method according to any one of claims 41-43, wherein the polymer molecules formed on the substrate has an average dry film thickness of at least 0.5 pm.

45. A method according to any one of claims 41-43, wherein the polymer molecules formed on the substrate has an average dry film thickness of at least 1 pm.

46. A method according to any one of claims 41-45, wherein each of the monomer; the second monomer; the third monomer; and the fourth monomer independently is comprised in a reaction composition comprising:a catalyst;a ligand;an activator; anda solvent.

47. A method according to claim 46. wherein the catalyst is obtained from Cu, Fe or Ru.

48. A method according to claim 46, wherein the ligand is selected from N,N,N’,N”,N”,-penta-methyldiethylene-triamine (PMDETA), tris [2-(dimethylamino)ethyl] amine (MeeTREN), tris(2-aminoethyl)amine (TREN). tris(2-pyridylmethyl)amine (TPMA), 1,1,4,7,10.10-hexamethyl-tri ethylenetetramine (HMTETA), tetramethylethylenediamine (TMEDA), 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (MeiCyclam). and / or 2,2’-bipyridyl (BiPy).

49. A method according to claim 46, wherein the activator is selected from sodium ascorbate (NaAsc). ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose, glucose with GOX, and / or pyrogallic acid.

50. A method according to any one of claims 46-49, wherein the reaction composition further comprises a buffer.IPTS / 128973811 151. A method according to any one of claims 46-49, wherein the reaction composition further comprises a halogen salt.

52. A method according to any one of claims 46-49, wherein the reaction composition further comprises a surfactant.

53. A method according to any one of claims 46-49, wherein the reaction composition further comprises a polyquatemium compound.

54. A method according to any one of claims 46-53, wherein each of the first polymer molecule, the second polymer molecule, the third polymer molecule, and the fourth polymer molecule independently are copolymers.

55. A method according to any one of claims 46-54, wherein each of the first monomer; the second monomer; the third monomer; and the fourth monomer independently is selected from 2-hydroxyethyl methacrylate (HEMA), glycidyl methacrylate (GMA), n-butyl methacrylate (BuMA), tert-butyl methacrylate (tBMA), benzyl methacrylate (BnzMA), 2-ethylhexyl methacrylate (EHMA), 2-hydroxyethyl acrylate (HEA), and styrene (St), or a combination thereof.

56. A method according to claim 55, wherein the first monomer is 2-hydroxyethyl methacrylate (HEMA) or styrene (St).

57. A method according to claim 55, wherein the second monomer is 2-hydroxyethyl methacrylate (HEMA) and benzyl methacrylate (BnzMA), 2-hydroxyethyl methacrylate (HEMA) and n-butyl methacrylate (BuMA), 2-hydroxyethyl methacrylate (HEMA) and 2-ethylhexyl methacrylate (EHMA), 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxylthyl acrylate (HEA), or 2-hydroxyethyl methacrylate (HEMA) and styrene (St).

58. A method according to any one of claims 46-57, wherein a ratio of the first polymerization initiators on the surface of the substrate to non-polymerizing initiator sites on the surface of the substrate is controlled within a certain range.IPTS / 128973811 159. A method according to claim 58, wherein the ratio is controlled by converting a portion of the first polymerization initiators to non-polymerizing initiators.

60. A method according to claim 58 or 59, wherein the ratio of first polymerization initiators to non-polymerizing initiator sites on the surface ofthe substrate is 1:1, 1:25, 1:40, 1:50, 1:75, 1:100, or 1:200.

61. A device structure comprising a substrate and surface polymer according to any one of claims 1-37, and further comprising a layer of material over the surface polymer, the layer of material being physically and / or chemically bonded to the surface polymer, wherein the material of the layer and the material of the substrate have different coefficients of thermal expansion.

62. A device structure according to claim 61, wherein the substrate is a glass substrate and the layer of material is a metal layer.

63. A device structure according to claim 62, wherein the surface polymer accommodates stress between the glass substrate and the metal layer over a temperature change of at least 100 Kelvin.

64. A device structure according to claim 62, wherein the surface polymer accommodates stress between the glass substrate and the metal layer over a temperature change of at least 200 Kelvin.

65. A device structure according to claim 62, wherein the polymer accommodates stress between the glass substrate and the metal layer over a temperature change of at least 300 Kelvin.

66. A device structure according to claim 62, wherein the metal layer is a copper layer.

67. A device structure according to claim 62, wherein the surface polymer has an average dty film thickness of at least 0.5 pm.

68. A device structure according to claim 62, wherein the surface polymer has an average dry film thickness of at least 1 pm.

69. A device structure according to claim 62. wherein the surface polymer has an average dry film thickness of at least 2 pm.IPTS / 128973811 170. A device structure according to claim 62. wherein the surface polymer has an average dry film thickness of at least 5 pm.

71. A system for forming surface polymers according to the method of any one of claims 38-60, comprising:a first container containing a reaction composition for forming the first polymer molecules at first polymerization initiator sites on the surface of the substrate;a second container containing chemistry for forming second polymerization initiator sites on the first polymer molecules;a third container for forming second polymer molecules on the first polymer molecules at the second polymerization initiator sites; anda substrate displacement device for bringing at least a portion of first polymerization initiator-modified substrate into contact with the reaction composition in the first container for a first controlled time, wherein the controlled time is sufficient for first polymer molecules to be formed on the portion of the polymerization initiator-modified substrate, then for bringing the at least a portion of the substrate into contact with the chemistry in the second container for a second controlled time, wherein the second controlled time is sufficient for second initiator sites to be formed on the first polymer molecules, and then for bringing the at least a portion of the substrate into contact with the reaction composition in the third container for a third controlled time, wherein the third controlled time is sufficient for second polymer molecules to be formed on the second initiator sites on the first polymer molecules;a substrate displacement device for bringing at least a portion of first polymerization initiator-modified substrate into contact with the reaction composition in the first container for a first controlled time, wherein the controlled time is sufficient for first polymer molecules to be formed on the portion of the polymerization initiator-modified substrate, then for bringing the at least a portion of the substrate into contact with the chemistry in the second container for a second controlled time, wherein the second controlled time is sufficient for second initiator sites to be formed on the first polymer molecules, and then for bringing the at least a portion of the substrate into contact with the reaction composition in the third container for a third controlled time, wherein the third controlled time is sufficient for second polymer molecules to be formed on the second initiator sites on the first polymer molecules.IPTS / 128973811 172. The system according to claim 71, wherein one or more of the polymer molecules are copolymers.

73. A system according to claim 71, further comprising at least one container containing chemistry for forming polymerization initiators on a surface of the substrate.

74. A system according to claim 71, further comprising at least one container containing chemistry for rinsing the substrate.

75. A system according to claim 71, further comprising at least one container for drying and / or annealing the substrate.

76. A system according to claim 73, wherein the at least one container for forming polymerization initiators is a vacuum oven.

77. A system according to claim 75, wherein the at least one container for drying and / or annealing the substrate is an oven.IPTS / 128973811 1

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