Selective quenching and initiation of a polymerization reaction

Abstract

Disclosed herein are methods for quenching surface polymer formation on a substrate, for initiating a surface polymer formation on a substrate, and for quenching and re-initiating surface polymer formation on a substrate. Systems for carrying out the methods disclosed herein are also encompassed by the disclosure.

Description

[0001] Selective Quenching and Initiation of a Polymerization Reaction

[0002] Cross-Reference to Related Applications

[0003] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 623,525, titled “Selective Quenching and Initiation of a Polymerization Reaction,” and filed January 22, 2024, the disclosure of which is incorporated by reference in its entirety herein.

[0004] Field

[0005] Disclosed herein are methods for quenching (i.e., for stopping or discontinuing) a propagation of polymeric units (monomers) to form polymer chains on a surface. Also disclosed herein are methods for selectively initiating and re-initiating (reviving) the process of polymer chain formation on surfaces. Quenching, initiating and re-initiating may also be applied in methods where multiple substrates are to be decorated with surface polymers in a sequential manner. Systems for carrying out the methods disclosed herein are also encompassed by the disclosure.

[0006] Background

[0007] Forming polymeric structures on surfaces have become increasingly important in many technologies and applications. “Surface polymers”, “surface bound polymers” or “polymers on a surface” may all describe a polymeric structure having polymer chains that are chemically bonded to a surface at one end through covalent bond, although the terminology may also be used to describe polymers that a spin coated on a surface. 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”-approach (Fig. 1), polymers are usually pre-prepared 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 self-assemble on said surface forming surface bound polymers. In the “grafting fronf’-approach (Fig. 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 bonded on the surface. Accordingly, surface polymers are formed from the surface monomer-by-monomer. The “grafting to’' approach allows for simple preparation procedures and detailed characterization, since the polymers may be prepared using conventional methods, and such polymers may maintain the bonding-to-surface property of the one end of the pre-formed polymer. Then, the self-assembly procedure may be initiated using the preservation and ability of the viable ends to attach to the surface. However, the “grafting to'’-approach lacks 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 polymer 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 self-assemble 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.

[0008] 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.

[0009] 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. They may be used, for example, for storing certain chemical species, controlling transport properties, improving surface stability and properties, creating an interface in which dissimilar materials can bind or interact, and other functions. Surface polymers can subsequently join otherwise incompatible materials such as metals and plastics and improve adhesion between such otherwise incompatible materials (see, e.g., WO 2014 / 075695 Al).

[0010] 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" with a wide range of uses, varying from redox activity to biocompatibility and surface alteration, and due to the flexibility7of the surface polymers, highly tailored thin films of surface polymers can be created with respect to chemical composition, thickness, density and architecture.

[0011] However, there is still a desire to obtain additional control over the rate of formation of surface polymers.

[0012] Summary

[0013] In accordance with an aspect of the disclosure, there is provided a method for selectively quenching a surface polymer formation reaction comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising at least one monomer, at least one ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent, for forming surface polymers from the polymerization initiator-modified sites, and quenching the propagation of surface polymer formation by lowering the pH of the polymerization composition below the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst. In accordance with an aspect of the disclosure, there is provided a method for selectively quenching a surface polymer formation reaction comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising at least one monomer, at least one ligand being a nitrogen-containing ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent being a mixture with water, and reversibly quenching the propagation of surface polymer formation by lowering the pH of the polymerization composition below the pKaHi of the complex formed between the at least one ligand and the at least one catalyst to decompose the complex formed between the at least one ligand and the at least one catalyst. The pH may be lowered using an organic or inorganic acidic substance. The acidic substance may be selected from methanesulfonic acid (MSA), hydrochloric acid (HC1), sulfuric acid (H2SO4), phosphoric acid (H3PO4), 2,2,2-trifluoroacetic acid (TFA), p-toluenesulfonic acid (pTSA), and nitric acid (HNO3) as well as combinations thereof. Furthermore, the reaction composition may further comprise a buffer. The buffer may have more than one pKa value. The buffer may be selected carbonate buffer, glycine buffer, citrate buffer, phosphate buffer, acetate buffer, ammonium buffer (ammonium chloride / ammonia), formate buffer, sodium ascorbate / ascorbic acid buffer, and zwitterionic buffers such as Good's buffers as well as combinations thereof. Furthermore, the Good’s buffer may be selected from MES, PIPES, MOPS, HEPES, CHES, CAPSO and CAPS, and combinations thereof. Furthermore, an inorganic salt may be added during or prior to surface polymer formation. The inorganic salt may be selected from NaCl, NaBr, KC1, KBr, MgCh, MgBn, CaCh. HC1. HBr. LiCl, LiBr, CaBn, CuBn and CuCb as well as combinations thereof. The ligand may be selected from A.A.A’.A”, A’ ’-penta- methyldiethylene-triamine (PMDETA), tris [2-(dimethylamino)ethyl] amine (MeeTREN), tris(2- aminoethyl)amine (TREN), tris(2-pyridylmethyl)amine (TP MA), 1,1,4,7,10,10-hexamethyl- triethylenetetramine (HMTETA), tetramethylethylenediamine (TMEDA), 1,4,8,11-tetramethyl- 1.4.8.11-tetraazacyclotetradecane (Me4Cyclam), and 2.2’ -bipyridyl (BiPy) as well as combinations thereof. Furthermore, the oxygen concentration of the reaction composition is controlled during the surface polymer formation. The oxygen concentration may be below a partial pressure of 25 hPa. Furthermore, the oxygen concentration may be controlled using an oxygen scavenger. The oxygen scavenger may be selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid as well as combinations thereof. Furthermore, the at least one catalyst activator may be an oxygen scavenger selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid as well as combinations thereof. The complex formed between the catalyst and the ligand may be selected from Cu / MeeTREN, Cu / PMDETA, Cu / TPMA, Cu / TREN, Cu / HMTETA, Cu / TMEDA and Cu / Me4Cyclam, and combinations thereof. The substrate may be selected from metal, glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composites, plastics, and particles, as well as combinations thereof. Furthermore, the substrate may be nanoparticles, such as nanoparticles having a silicon core.

[0014] In accordance with an aspect of the present disclosure, there is provided a method of initiating a surface polymer formation reaction comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising at least one monomer, at least one ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent, for forming surface polymers from polymerization initiator-modified sites, wherein the pH of the reaction composition is below the pKJH of the complex formed between the at least one ligand and the at least one catalyst, and initiating surface polymer formation from the polymerization initiator-modified sites by raising the pH of the reaction composition above the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst. In accordance with an aspect of the present disclosure, there is provided a method of initiating a surface polymer formation reaction comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising at least one monomer, at least one ligand being a nitrogen-containing ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent being a mixture with water, for forming surface polymers from polymerization initiator-modified sites, wherein the pH of the reaction composition is below the pKakk of the complex formed between the at least one ligand and the at least one catalyst, and initiating surface polymer formation from the polymerization initiator-modified sites by raising the pH of the reaction composition above the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst to reassemble the complex formed between the catalyst and the ligand. The initiating surface polymer formation may be before the bringing of at least a portion of the polymerization initiator-modified substrate into contact with the reaction composition. The surface polymer formation may be re-initiated by raising the pH of the reaction composition above the pKaHi of the complex formed between the at least one ligand and the at least one catalyst. The pH may be raised using an alkaline substance. The alkaline substance may be selected from potassium hydroxide (KOH), lithium hydroxide (LiOH) tripotassium phosphate (K3PO4), sodium carbonate (NazCCh), or sodium ethoxide (CFECFbONa) as well as combinations thereof. Furthermore, the reaction composition may further comprise a buffer. The buffer may have more than one pKa value. The buffer may be selected carbonate buffer, glycine buffer, citrate buffer, phosphate buffer, acetate buffer, ammonium buffer (ammonium chloride / ammonia), formate buffer, sodium ascorbate / ascorbic acid buffer, and zwitterionic buffers such as Good’s buffers as well as combinations thereof. Furthermore, the Good’s buffer may be selected from MES, PIPES, MOPS, HEPES, CHES, CAPSO and CAPS, and combinations thereof. Furthermore, the oxygen level of the reaction composition is controlled during the re-initiation of the reaction composition. The oxygen concentration may be below a partial pressure of 25 hPa. Furthermore, the oxygen concentration may be controlled using an oxygen scavenger. The oxygen scavenger may be selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose wi th GOx, and pyrogallic acid as well as combinations thereof. The ligand may be selected from TV, TV, TV’, TV”, 7V”’- 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), tetramethylethylene-diamine (TMEDA), 1,4,8,11- tetramethyl-l,4,8,l l-tetraazacyclotetradecane (MerCy clam), and 2,2 ’-bipyridyl (BiPy) and combinations thereof. Furthermore, the reaction composition may comprise an inorganic salt selected from NaCl, NaBr, KC1, KBr, MgCb, MgBn, CaCb, HC1. HBr. LiCl, LiBr, CaBn, CuBn and CuCb as well as combinations thereof. Furthermore, the reaction composition may comprise a buffer. Furthermore, the catalyst activator may be an oxygen scavenger. The oxygen scavenger may be selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid, and combinations thereof. The complex formed between the catalyst and the ligand is selected from Cu / MeeTREN, Cu / PMDETA, Cu / TPMA, Cu / TREN, Cu / HMTETA, Cu / TMEDA, and Cu / MerCyclam. and combinations thereof. The substrate may be selected from metal, glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composites, plastics, and particles, as well as combinations thereof. Furthermore, the substrate may be nanoparticles, such as nanoparticles having a silicon core.

[0015] In accordance with the present disclosure, there is provided a method for forming surface polymers comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, comprising: at least one monomer, at least one ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent, to form surface polymers from the polymerization initiator-modified sites, quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKJ-fc of the complex formed between the at least one ligand and the at least one catalyst, and raising the pH of the reaction composition above the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst to re-initiate the formation of surface polymers. In accordance with the present disclosure, there is provided a method for forming surface polymers comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, comprising at least one monomer, at least one ligand being a nitrogen-containing ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent being a mixture with water, to form surface polymers from the polymerization initiator-modified sites, reversibly quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKaHz of the complex formed between the at least one ligand and the at least one catalyst to decompose the complex formed between the at least one ligand and the at least one catalyst, and raising the pH of the reaction composition above the pK>H2 of the complex formed betw een the at least one ligand and the at least one catalyst to reassemble the complex formed between the at least one ligand and the at least one catalyst to re-initiate the formation of surface polymers. The pH may be lowered using an acidic substance. The acidic substance may be an organic or an inorganic acid substance. The acidic substance may be selected from methanesulfonic acid (MSA), hydrochloric acid (HC1), sulfuric acid (H2SO4), phosphoric acid (H3PO4), 2,2,2-trifluoroacetic acid (TFA), / 2-toluenesulfonic acid (pTSA), and nitric acid (HNO3 as well as combinations thereof. Furthermore, the pH may be raised using an alkaline substance. The alkaline substance may be selected from potassium hydroxide (KOH), lithium hydroxide (LiOH) tripotassium phosphate (K PO4), sodium carbonate (Na2CO ), and sodium ethoxide (CHsCH2ONa) as well as combinations thereof. Furthermore, the reaction composition may further comprise a buffer. The buffer may have more than one pKa value. The buffer may be selected carbonate buffer, glycine buffer, citrate buffer, phosphate buffer, acetate buffer, ammonium buffer (ammonium chloride / ammonia), formate buffer, sodium ascorbate / ascorbic acid buffer, and zwitterionic buffers such as Good’s buffers as well as combinations thereof. Furthermore, the Good’s buffer may be selected from MES, PIPES, MOPS, HEPES, CHES, CAPSO and CAPS, and combinations thereof. Furthermore, the oxygen level of the reaction composition may be controlled during the re-initiation of the reaction composition. The oxygen concentration may be kept below a partial pressure of 25 hPa. The oxygen concentration may be controlled using an oxygen scavenger. The oxygen scavenger may be selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid as well as combinations thereof. The ligand may be selected from N,N, A’, / V' .r'"-pentamethyldiethylene-tnamine (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-tetraazacyclotetradecane (MerCyclam), and 2,2’-bipyridyl (BiPy) as well as combinations thereof. Furthermore, the reaction composition may comprise an inorganic salt selected fromNaCl, NaBr, KC1, KBr, MgCk, MgBn. CaCh, HC1, HBr, LiCl, LiBr, CaBr?. CuBn and CuCb, as well as combinations thereof. The substrate may be selected from metal, glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composites, plastics, and particles, as well as combinations thereof. Furthermore, the substrate may be nanoparticles, such as nanoparticles having a silicon core.

[0016] In accordance with an aspect of the present disclosure, there is provided a method for forming surface polymers comprising: providing a reaction composition comprising at least one monomer, a least one ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator and at least one solvent bringing at least a portion of a first polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said substrate, quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKaH? of the complex formed between the at least one ligand and the at least one catalyst, withdrawing said first substrate from the reaction composition, re-initiating the surface polymer formation by raising the pH of the reaction composition above the pKJ-b of the complex formed between the at least one ligand and the at least one catalyst, bringing at least a portion of a second polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said second substrate, and optionally quenching the surface polymer formation by lowering the pH of the reaction composition below the pKaH2 of the complex formed between the at least one catalyst and the at least one ligand prior to withdrawing said second substrate from the reaction composition. In accordance with an aspect of the present disclosure, there is provided a method for forming surface polymers comprising: providing a reaction composition comprising at least one monomer, a least one ligand being a nitrogen-containing ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent being a mixture with water, the reaction composition having a pH above the pK.H? of the complex formed between the ligand and the catalyst, bringing at least a portion of a first polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said substrate, reversibly quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKJH of the complex formed between the at least one ligand and the at least one catalyst to decompose the complex formed between the at least one ligand and the at least one catalyst, withdrawing said first substrate from the reaction composition, re-initiating the surface polymer formation by raising the pH of the reaction composition above the pKJTz of the complex formed between the at least one ligand and the at least one catalyst to reassemble the complex formed between the at least one catalyst and the at least one ligand, and bringing at least a portion of a second polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said second substrate, and optionally reversibly quenching the surface polymer formation by lowering the pH of the reaction composition below the pKaH2 of the complex formed between the at least one catalyst and the at least one ligand to decompose the complex formed between the catalyst and the ligand prior to withdrawing said second substrate from the reaction composition. The acidic substance may be an organic or an inorganic acid substance. The acidic substance may be selected from methanesulfonic acid (MSA), hydrochloric acid (HC1), sulfuric acid (H2SO4), phosphoric acid (H3PO4), 2.2.2-trifluoroacetic acid (TFA). / Moluenesulfonic acid (pTSA). and nitric acid (HNO3 as well as combinations thereof. Furthermore, the pH may be raised using an alkaline substance. The alkaline substance may be selected from potassium hydroxide (KOH), lithium hydroxide (LiOH) tripotassium phosphate (K3PO4), sodium carbonate (NazCOs), and sodium ethoxide (CHsCH2ONa) as well as combinations thereof. Furthermore, the reaction composition may further comprise a buffer. The buffer may have more than one pK> value. The buffer may be selected carbonate buffer, glycine buffer, citrate buffer, phosphate buffer, acetate buffer, ammonium buffer (ammonium chloride / ammonia), formate buffer, sodium ascorbate / ascorbic acid buffer, and zwitterionic buffers such as Good's buffers as well as combinations thereof. Furthermore, the Good’s buffer may be selected from MES, PIPES, MOPS, HEPES, CHES, CAPSO and CAPS, and combinations thereof. Furthermore, the oxygen level of the reaction composition is controlled during the re-initiation of the reaction composition. The oxygen concentration may be kept below a partial pressure of 25 hPa. The oxygen concentration may be controlled using an oxygen scavenger. The oxygen scavenger may be selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOX, and pyrogallic acid, as well as combinations thereof. The ligand may be selected from MA.A'. ' .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-hexamethyltriethylenetetramine (EIMTETA), tetramethylethylenediamine (TMEDA), 1,4,8.11 -tetramethyl- 1.4.8.11-tetraazacyclotetradecane (NteiCyc- lam), and 2,2’-bipyridyl (BiPy) as well as combinations thereof. Furthermore, the reaction composition may comprise an inorganic salt selected fromNaCl, NaBr, KC1, KBr, MgCh, MgBn, CaCh, HC1, HBr, LiCl, LiBr, CaBr2, CuBn and CuCh, as well as combinations thereof. The substrate may be selected from metal, glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composites, plastics, and particles, as well as combinations thereof. Furthermore, the substrate may be nanoparticles, wherein nanoparticles may have a silicon core.

[0017] The methods described above may be such, wherein the ligand may selected fromN,N,N’,N”,N”'- pentamethyldiethylenetriamine (PMDETA), tris [2-(dimethylamino)ethyl] amine (MeeTREN), tris(2-aminoethyl)amine (TREN), tris(2-pyridylmethyl)amine (TPMA), 1, 1, 4,7, 10,10-hexamethy- Itriethylenetetramine (HMTETA), tetramethylethylenediamine (TMEDA), 1,4,8,11-tetramethyl- 1,4, 8,11-tetraazacyclotetradecane (Me-iCyclam), and 2, 2‘ -bipyridyl (BiPy) as well as combinations thereof, wherein the catalyst may be selected from copper (Cu), iron (Fe), ruthenium (Ru), or titanium (Ti), wherein the catalyst activator may be an oxygen scavenger selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid as well as combinations thereof and wherein the oxygen control agent may be an oxygen scavenger selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid.

[0018] In accordance with the present disclosure, there are provided systems for forming surface polymers on a substrate according to any method described herein, wherein the systems may comprise: a reaction composition container for containing a reaction composition; and a substrate displacement device for bringing at least a portion of a polymerization initiator-modified substrate into contact with the reaction composition in the reaction composition container, and for removing the polymerization initiator-modified substrate from the reaction composition; and a means for quenching the surface polymer formation reaction on the substrate; wherein the substrate displacement device is configured to maintain the portion of the polymerization initiator-modified substrate in contact with the reaction composition to enable surface polymers to be formed on the portion of the polymerization initiator-modified substrate. The systems may further comprise a pH control agent dispenser for providing the acid or base for the quenching and / or the initiating and / or the re-initiating. Furthermore, the pH control agent dispenser may be enabled for quenching the surface polymer formation reaction on the substrate following withdrawal of the substrate from the reaction composition. The systems may further comprise a quenching container for quenching the surface polymer formation by lowering the pH of any reaction composition remaining on the surface of the polymerization initiator-modified substrate below the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst, and wherein the substrate displacement device is configured to move the polymerization initiator-modified substrate from the reaction composition chamber to the quenching container.

[0019] Description of the drawings

[0020] 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: Fig. 1 illustrates the ‘"grafting to” concept schematically.

[0021] Fig. 2 illustrates the “grafting from” concept schematically.

[0022] Fig. 3 illustrates an idealized data set for the acidic quenching of an ongoing polymerization.

[0023] Fig. 4 illustrates theoretical, stable surface polymer formation rate in case of a linear dependency between surface polymer length and polymerization time.

[0024] Fig. 5 illustrates theoretical, stable surface polymer formation rate in case of a non-linear dependency between surface polymer length and polymerization time.

[0025] Fig. 6 is a schematic illustration of a system for forming surface polymers on at least a portion of a substrate.

[0026] Fig. 7 is a schematic illustration of an exemplary substrate displacement device, the substrate displacement device comprising a roll-to-roll processing device, in accordance with an embodiment.

[0027] Fig. 8 is a process flow chart illustrating an iterative process for controlling the pH of the reaction composition.

[0028] Fig. 9 is a process flow chart illustrating an iterative process for controlling the oxygen concentration of the reaction composition. Fig. 10 is a detailed schematic illustration of the reaction composition container comprising the reaction composition shown in Fig. 5. in accordance with an embodiment.

[0029] Fig. 11 is a process flow chart illustrating the different processing steps comprised in a system for forming surface polymers in accordance with an embodiment.

[0030] Fig. 12 pertains to Example 7 and shows UV / Vis data of Cu / MeeTREN complex in Dl-water at different pH values.

[0031] Fig. 13 pertains to Example 7 and shows UV / Vis absorption of Cu / MeeTREN complex in DI- water at X=699, 1=870 nm as function of pH.

[0032] Fig. 14 pertains to Example 7 and shows UV / Vis data of Cu / PMDETA complex in Dl-water at different pH values.

[0033] Fig. 15 pertains to Example 7 and shows UV / Vis absorption of Cu / PMDETA in Dl-water at 1=699, 1=870 nm as function of pH.

[0034] Fig. 16 pertains to Example 7 and shows UV / Vis data of Cu / TPMA in DI-water / EtOH at different pH values.

[0035] Fig. 17 pertains to Example 7 and shows UV / Vis absorption of Cu / TPMA in DI-water / EtOH at 1=699, 1=870 nm as function of pH.

[0036] Fig. 18 pertains to Example 8 and shows decomposition and reassembly of Cu / MeeTREN in glycine-buffered Dl-water by UV / Vis data.

[0037] Fig. 19 pertains to Example 9 and shows quenching with an acidic substance of an ongoing surface polymer formation after different polymerization times.

[0038] Fig. 20 pertains to Example 9 and shows the calculated extent of quenching.

[0039] Fig. 21 pertains to Example 10 and shows ellipsometric data (thickness of formed surface polymers) with time when a reaction composition was subjected to quenching and reinitiation.

[0040] Fig. 22 pertains to Example 11 and shows ellipsometric data (thickness of formed surface polymers) with time, when a reaction composition was subjected to two cycles of quenching and re-initiation.

[0041] Fig. 23 pertains to Example 12 and shows ellipsometric data (thickness of formed surface polymers) with time, when a reaction composition was subjected to quenching and reinitiation with H2SO4 as acidic substance and LiOH as alkaline substance.

[0042] Fig. 24 pertains to Example 13 and shows ellipsometric data (thickness of formed surface polymers) with time, when a reaction composition was subjected to quenching and reinitiation Fig. 25 pertains to Example 14 and shows ellipsometric data (thickness of formed surface polymers) after a first surface polymer formation with quenching and a second surface polymer formation to obtain a surface block copolymer.

[0043] Fig. 26 pertains to Example 15 and shows thermogravimetric (TGA) data of silicon nanoparticles (SiNP) subjected to surface polymer formation in a reaction composition quenched by acidification after different polymerization times.

[0044] Fig. 27 pertains to Example 15 and shows organic wl% of surface polymer formed on silicon nanoparticles (SiNP) as function of time before quenching by acidification.

[0045] Fig. 28 pertains to Example 16 and shows thermogravimetric (TGA) data of silicon nanoparticles (SiNP) subjected to surface polymer formation in a reaction composition, where the reaction composition was quenched and then re-initiated.

[0046] Fig. 29 pertains to Example 16 and shows organic wt% of surface polymer formed on silicon nanoparticles (SiNP) before quenching and formed surface polymers after re-initiation.

[0047] Fig. 30 shows three quenching events and subsequent surface polymer formations, see Example

[0048] 17.

[0049] Detailed description of the invention

[0050] Disclosed herein is a method for selectively quenching a surface polymer formation reaction comprising adding a substance to the reaction composition in which the surface polymer formation reaction is taking place to adjust the pH of the reaction composition to a pH value at which the surface polymer formation reaction may no longer occur.

[0051] Disclosed herein is a method for selectively re-initiating a surface polymer formation reaction comprising adding a substance to the reaction composition in which the surface polymer formation reaction is taking place to adjust the pH of the reaction composition to a pH value at which the surface polymer formation reaction may again occur.

[0052] Disclosed herein is a method for selectively quenching a surface polymer formation reaction comprising adding a substance to the reaction composition in which the surface polymer formation is taking place to adjust the pH of the reaction composition to a pH value at which the surface polymer formation reaction may no longer take place, followed by selectively re-initiating a surface polymer formation reaction by adding a substance to the reaction composition in which the surface polymer formation reaction is taking place to adjust the pH of the reaction composition to a pH value at which the surface polymer formation reaction may again take place.

[0053] In general, surface polymers may be formed on at least a portion of a substrate using various procedures.

[0054] 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. SARA-ATRP and SET-LRP are described, e.g., in https: / / www.cmu.edu / maty / atrp-how / procedures-for- initiation-of-ATRP / SARA-ATRP-or-SET-LRP.html. Both the SET-LRP and (ARGET) ATRP method CuCh or CuBn in the case of ARGET ATRP, and 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.

[0055] Surface-Initiated Surface Polymer formation is described in WO 2024 155981 and WO 2019 196999. WO 2019 196999 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 since 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).

[0056] In surface polymer formation reactions, the reagents typically comprises at least catalyst, ligand for the catalyst, monomer and solvent. This also applies within the present context, where a reaction composition comprising at least one monomer, at least one ligand, at least one catalyst, at least one catalyst activator, and at least one solvent may be used for surface polymer formation. The catalyst and the ligand form a complex, catalyzing surface polymer formation from available polymerization initiator-modified sites on a surface of a substrate. Depending on, i.a, catalyst, ligand and monomer used, surface polymers may be propagated (formed) with a certain rate and / or a certain rate profile. Depending on the reaction kinetics and the rate of a surface polymer formation, control of the time window in which polymer formation occurs may be of interest to obtain specific surface polymer characteristics such as chain length, viability of functional chain ends for further polymer formation (the ability to initiate an additional, subsequent surface polymer formation event (block polymer formation)), and polydispersity index. Polymerization control generally prescribes well-defined time points for surface polymer formation initiation and surface polymer formation termination. Initiation of a surface polymer formation is typically well-defined as the point in time where the polymerization initiator-modified surface is brought into contact with the reagents needed for surface polymer formation. Termination of a surface polymer formation may similarly be well-defined as the point in time where the surface (at which surface polymers are formed) is removed from contact with reagents for surface polymer formation. However, e.g.. in cases where the substrate comprises micro- or nanoscale entities such as nanomaterials, recovery of a substrate from a polymerizing reaction composition may require time-demanding steps such as filtration or centrifugation. Since a surface polymer formation reaction is a time-dependent chemical process, a surface polymer formation reaction may continue in the time interval spent on recovering a substrate from the reaction composition, leading to uncertainties in the de facto polymerization time. This may apply to all types and shapes of substrates.

[0057] By utilizing the addition of a substance which quenches the polymerizing ability of a reaction composition within a short time relative to the total polymerization time, a time interval for substrate surface polymer formation may be defined with low uncertainty, allowing for improved control of a time-dependent surface polymer formation. Selection of the time interval will depend on “manufacturability'’', e.g., throughput, cost, pre-processing and post-processing of substrates.

[0058] By utilizing the addition of a substance which reverses the effects of quenching substance addition to a reaction composition, a quenched reaction composition may be re-initiated to allow for additional surface polymer formation events to proceed in said reaction composition. Within the present context, the expressions “re-initiate’', “reactivate"’ and “revive” may be used interchangeably. To solve the aforementioned challenges with precisely defined polymerization times, the state of the art suggests a strategy to access and oscillate between activated and deactivated states of a catalyst in the surface polymer formation, i.e., the usage of light-induced radical polymerizations, where propagation of polymers slows down in the absence of light and resumes once light is supplied. On a large scale, uniform irradiation across the entire body of a reaction composition is challenging. Furthermore, for compositions containing light-absorbing substrates, e.g., nanomaterials, shadowing effects may impede penetration of light and thus minimize control over the polymerization reaction. A related known strategy relies on simplified electrochemically mediated atom transfer radical polymerizations (seATRP) which depend on continuous redox chemistry’ to ensure monomer turnover, and thus may be paused by disabling the current. On a large scale, efficient electrochemical stopping and starting a polymerization reaction occurs only in a fraction of the liquid used for the polymerization, namely that in close proximity to the electrode. Another known strategy is such which utilizes the addition of a chemical species displaying high binding affinity’ toward the catalyst and has been shown where irreversible catalyst poisoning allows for termination of the polymer formation reaction. In oxygen-sensitive SET-LRP and ARGET ATRP polymerizations, the polymer formation takes place under inert atmosphere, since exposure to oxygen (atmospheric) terminates polymer propagation due to very fast inactivation of the catalyst.

[0059] The inventors have surprisingly found that a surface polymer formation reaction can be selectively quenched by adjusting the pH of the reaction composition below the value, where the complex formed between the at least one ligand and the at least one catalyst may form a stable complex (a complex that is not degraded or decomposed). This offers an elegant and easy, reproducible method for controlling surface polymer formation events. The inventors have found that the pH value at which the surface polymer formation quenches is dependent on the pKa value of the complex formed between the at least one catalyst and the at least one ligand used in the surface polymer formation. Thus, an ongoing polymer formation reaction can be selectively quenched by lowering the pH below the pKa value of the complex between the at least one catalyst and the at least one ligand. It is further contemplated that the polymer forming ability of a reaction composition can be kept “at hold” at certain pH values and activated by increasing the pH above the pKa value of the complex formed between the at least one catalyst and the at least one ligand. In particular, the method of selectively quenching a surface polymer formation reaction as disclosed herein comprises: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition comprising: at least one monomer, at least one ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent, to form surface polymers from the polymerization initiator-modified sites, and quenching the surface polymer formation by lowering the pH of the reaction composition below the pKJ-h of the complex formed between the at least one ligand and the at least one catalyst. At a pH below the pKaHi of the complex formed between the ligand and the catalyst, the complex formed between the ligand and the complex will decompose, thus, the catalyst / ligand complex may no longer be active for catalyzing surface polymer formation.

[0060] The pH is suitably lowered using an acidic substance. Non-limiting examples of such acidic substances are organic or inorganic acidic substances, such as methanesulfonic acid (MSA) (organic), hydrochloric acid (HC1) (inorganic), sulfuric acid (H2SO4) (inorganic), phosphoric acid (H3PO4) (inorganic), 2,2,2-trifluoroacetic acid (TFA) (organic), p-toluenesulfonic acid (pTSA) (organic), and nitric acid (HNO3) (inorganic). Combinations of such acidic substances are also comprised.

[0061] Within the present context, pH and acid dissociation constants (pKa values) apply to complexes between a catalyst and a ligand, acids, bases, and solvents and mixtures thereof, where pH and Ka can meaningfully be determined. The pH value translates the concentration of hydrogen ion into a number between 0 and 14 in an aqueous environment. Since the complexes formed between a catalyst and a ligand used herein are more alkaline, the term pKaH is used, which refers to the pKa of the conjugate acid. The higher the pK.H value, the stronger the base. For species which may be protonated more than once, pKaHi refers to the pKa of the conjugate acid obtained after the “first” protonation, and pKJHb refers to the pKa of the conjugate acid obtained after the “second” protonation; pKaHi is in this case always higher than pKaHz, i.e., pKaHi > pKaH2. Specific pKa and pKaH values may be calculated using known titration methods, or, where available, be looked up in various publications and handbooks.

[0062] Well-suited ligands within the present context comprise nitrogen-containing ligands. Non-limiting 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, A V ' A \Ar''-pentamelhyldiethylene-triamine (PMDETA). tris- [2-(dimethylamino)ethyl] amine (Me6TREN), tris(2-aminoethyl)amine (TREN), tris(2-pyridyl- methyl)amine (TPMA), Cu / HMTETA ( 1,1, 4, 7, 10, 10-hexamethyltri ethylenetetramine), Cu / TMEDA (tetramethylethylenediamine), Cu / Me4Cyclam (1,4,8, 11 -tetramethyl- 1,4,8, 11- tetraazacyclotetradecane), 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 may be 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 used.

[0063] The catalyst of the reaction composition as defined herein may be based on a transition metal (as defined in the Periodic Table of Elements). Non-limiting examples of catalysts are compounds derived from transition metals like copper (Cu), iron (Fe), and ruthenium (Ru). . Specific examples of such catalyst compounds include CU2O, CuO, CuCl, CuCk, CuBr, CuBn, FeCk, FeCh, RuCb. and RuCh, as well as combinations thereof. The catalyst concentration in the reaction composition may typically be in the range 0.0001-1 mM. The concentration of catalyst in the reaction composition may be in the range 0.0001-0.32 mM, for example 0.001 mM, 0.01 mM, 0.02 mM, 0.04 mM, 0.08 mM, 0. 16 mM. or 0.32 mM. The activator for the catalyst (e.g., oxygen scavenger) may be used in excess compared to the catalyst. Excess catalyst activator may, e.g., be 10-250 times. In accordance with the methods disclosed herein, catalyst activator may be added several times during surface polymer formation to control surface polymer formation with progressing time. In a certain embodiment the catalyst is based on Cu, and is prepared from Cu oxides, or Cu chlorides as specified above.

[0064] Herein, the terms “complex formed between a ligand and a catalyst'’, “complex formed between a catalyst and a ligand”, and “catalyst / ligand complex” may be used interchangeably.

[0065] Herein, the term “catalyst” is used to denote the transition metal when the transition metal is coordinated with a ligand. One, two, or three ligands may form complexes with one transition metal catalyst. The term “catalyst compound” is used to denote the transition metal in combination with another ion. e.g., Cu oxides, and Cu chlorides, on which the catalyst may be based. In accordance with the principles of the present disclosure regarding the discussion of pKa values of the complex formed between the catalyst and the ligand, the inventors have determined the pKa values of certain complexes between copper (Cu) as catalyst and certain ligands (see the below Table 1) by titration (cf. Example 7). The pKaEh values of these complexes were confirmed by UV / Vis spectroscopic analysis to be the pH where protonation causes the characteristic absorbance profile of the catalyst / ligand complex to disappear, meaning that the complex is not, at that pH, a stable species. The pKaH? values of other catalyst / ligand complexes not included in Table 1 can be determined analogously.

[0066] Table 1. Catalyst / ligand complex pKaHi and pKaH2 values as determined by titration.

[0067] By way of example, when Cu is used as catalyst and MeeTREN is used as ligand, decreasing the pH below the pKJH leads to loss of color of the catalyst / ligand complex and UV / Vis absorption bands associated with the catalyst / ligand complex disappear, indicative of the dissociation of the complex between the catalyst and the ligand, leading to loss of polymer forming activity, leading to quenching of the surface polymer formation. The catalyst / ligand (complex formed between a ligand and a catalyst) is believed to decompose, causing reversible quenching of the surface polymer formation.

[0068] The inventors have surprisingly found that the catalyst and the ligand may be reassembled and again form a catalyst / ligand complex (cf. Example 8). when the pH of the reaction composition is raised above a pH corresponding to the pK.H? of the catalyst / ligand complex, leading to reinitiation of the surface polymer formation activity of the catalyst / ligand complex.

[0069] Thus, in another aspect, the present disclosure provides a method of initiating a surface polymer formation reaction comprising: bringing at least a portion of a polymenzation initiator-modified substrate into contact with a reaction composition comprising: at least one monomer, at least one ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent, wherein the pH of the reaction composition is below the pKJ-fi of the complex formed between the at least one ligand and the at least one catalyst, initiating surface polymer by raising the pH of the reaction composition above the pKal b of the complex formed between the at least one catalyst and the at least one ligand. Raising the pH above the p Tb of the complex formed between the ligand and the catalyst causes the catalyst / ligand complex to reassemble, and thus the formation of surface polymers may be initiated.

[0070] It is to be understood that the initiating surface polymer formation may be before the bringing at least a portion of the polymerization initiator-modified substrate into contact with the reaction composition. Initiating surface polymer formation may also take place following bringing at least a portion of the polymerization initiator-modified substrate into contact with the reaction composition. Initiating surface polymer formation may also take place with the bringing at least a portion of the polymerization initiator-modified substrate into contact with the reaction composition.

[0071] The pH may suitably be raised using an alkaline substance. Non-limiting examples of such alkaline substances include potassium hydroxide (KOH), lithium hydroxide (LiOH), tripotassium phosphate (K3PO4), sodium carbonate (Na2CO?). or sodium ethoxide (CHsC^ONa). as well as combinations thereof.

[0072] Accordingly, the catalyst / ligand complexes described herein makes possible the selective quenching of a surface polymer formation by addition of an acidic substance as well as make possible the selective re-initiation of a surface polymer formation of a quenched surface polymer formation by addition of an alkaline substance.

[0073] Thus, in another aspect, the present disclosure provides a method of forming surface polymers comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition to form surface polymers from the polymerization initiator-modified sites comprising: at least one monomer, at least one ligand, at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent, to form surface polymers from the polymerization initiator-modified sites, and quenching the surface polymer formation by lowering the pH of the reaction composition below the KaFb of the complex formed between the at least one catalyst and the at least one ligand, and raising the pH of the reaction composition above the pKJ-b of the complex formed between the at least one catalyst and the at least one ligand to re-initiate the formation of surface polymers. The surface polymer formation may be reversibly quenched due to decomposition of the complex formed between the ligand and the catalyst by lowering the pH below the pKaH2 of the catalyst / ligand complex. The surface polymer formation may be re-initiated by reassembly of the complex formed between the ligand and the catalyst by raising the pH above the pKJH of the catalyst / ligand complex.

[0074] For selectively quenching and re-initiating a surface polymer formation reaction, the catalysts and ligands mentioned above are suited. Likewise, acidic and alkaline substances mentioned above are suited for quenching and re-initiation, respectively.

[0075] It is to be understood that the surface polymer formation reaction may be quenched in order to recover the substrate from the reaction composition, or the reaction composition may be quenched for a certain time and then re-initiated to continue surface polymer formation, either on the same substrate or on a subsequent substrate.

[0076] Thus, in another aspect, the present disclosure provides a method of forming surface polymers comprising: providing a reaction composition comprising: at least one monomer, at least one ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex, at least one catalyst activator, and at least one solvent, bringing at least one portion of a first polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said first substrate, quenching the formation of surface polymers by lowering the pH of the reaction composition below the KaH2 of the complex formed between the at least one ligand and the at least one catalyst, withdrawing said first substrate from the reaction composition, re-initiating the formation of surface polymers by raising the pH of the reaction composition above the pKJ-fc of the complex formed between the at least one ligand and the at least one catalyst, and bringing at least a portion of a second polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said second substrate, and optionally quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKaH2 of the complex formed between the at least one ligand and l ' l the at least one catalyst prior to withdrawing said second substrate from the reaction composition. The surface polymer formation may be reversibly quenched due to decomposition of the complex formed between the ligand and the catalyst by lowering the pH below the pKaH2 of the catalyst / ligand complex. The surface polymer formation may be re-initiated by reassembly of the complex formed between the ligand and the catalyst by raising the pH above the pKaEb of the catalyst / ligand complex.

[0077] In the above methods, the at least one ligand may be a nitrogen-containing ligand. Non-limiting examples of nitrogen-containing ligands are given above. In the above methods, the solvent may be a mixture with water (i.e. an aqueous solvent). Non-limiting examples of solvents and mixtures are given below.

[0078] To further control the rate of the surface polymer formation, an oxygen control agent may be used in the methods described above during one or more of the steps.

[0079] With the expression ‘Tate of surface polymer formation” is meant that within a given timeframe, surface polymerization (propagation of polymer chains from polymerization initiation sites on the surface) occurs as a function of time to an extent where a certain surface polymer average dry film thickness on a surface is obtained. In some cases, the relationship between surface polymer average dry film thickness and polymerization time is linear as exemplified by Fig. 3. In other cases, the relationship between surface polymer average dry film thickness and polymerization time is nonlinear as exemplified by Fig. 4.

[0080] By the wording “stable rate” is meant the average thickness of surface polymers formed throughout multiple surface polymer formation events of the same duration (on multiple substrates in a sequential or consecutive manner) is within the standard deviation of the measured average dry film thickness. The acceptable variance in the average dry film thickness may depend on the average dry film thickness of the surface polymer and also on the intended application.

[0081] In general, three types of surface polymer “coatings” are known, namely:

[0082] 1) Preformed polymers which are deposited onto a substrate either as a polymer melt by e.g. a molding process, by doctor blading 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.

[0083] 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. The straight and linear polymer conformation is highly unfavored by entropy and is thus not generally observed for polymers in solution. However, 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” methodology7described below.

[0084] 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. Given the small size of such polymerization initiator molecules relative to a coiled coil polymer as described above, the density of such initiators on the surface can be much higher than that which is obtained when grafting polymer coiled coils directly to the surface in the “grafting to”-approach described above. Following polymerization initiator modificati- on / deposition, polymer chains are grown from these surface anchored initiators by extension of the polymer chain by 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 coiled 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.

[0085] It is to be understood that by the term “thickness of a surface polymer"’ is meant a surface polymer formed by propagating polymer chains (extension of a polymer chain by a monomer unit) from polymerization-initiators on the surface of a substrate during a certain time where the substrate is in contact with the reaction composition. The thickness is often measured as the dry film thickness by ellipsometry'. Thus, a targeted surface polymer thickness may be obtained within the applied predefined polymerization time, that is an average dry film thickness within the standard deviation during multiple surface polymer formation events as determined by dry film thickness of collapsed surface polymers. Generally’ speaking, a substrate with a surface polymer (for ellipsometry) is herein considered dry’ when no visible solvent film, droplets, or residues are observed with the naked eye on the surface of the substrate. Other methods of obtaining a dry substrate may be used, some of which include withdrawal of the substrate(s) from the reaction composition, followed by rinsing by sonication in Dl-water for 5 minutes, followed by sonication in acetone for 5 minutes, and dry ing in ambient air 1-30 minutes. In some cases, the substrates may be flushed with acetone after withdrawal from the reaction composition, followed by air-dry ing in an oven at 80°C for 15 minutes. Still, in some cases, the substrate(s) may be flushed with acetone, then sonicated in acetone for 5 minutes and left to dry at 80°C for 10 minutes. Alternative, the substrate(s) may be flushed with iPrOH, then sonicated in iPrOH for 5 minutes and left to dry’ under nitrogen flow for 10-30 minutes. 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’. Other means such as reflectometry or by measuring a step edge in the coating by atomic force microscopy or profilometry may be used to determine a thickness of a surface polymer. Generally speaking, a substrate with a surface polymer fdm is considered dry when no visible solvent fdm, droplets, or residues are observed on the surface of the substrate. Measurements such as atomic force microscopy 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.

[0086] The properties of surface polymers formed on the surface of a substrate depend on the length of surface polymers (number of monomeric units in the chain(s)) formed on the substrate. This is also referred to as “thickness’7of surface polymer layer. The achievable thickness depends on several factors, e.g., availability and density of polymerization initiators on the substrate, the monomer for surface polymer formation and reaction conditions such as the rate of surface polymer formation. Controlling and predicting the thickness of the formed surface polymer with high precision may prove very valuable. Thus, ensuring a fundamental understanding and repeatability of a surface polymer formation on a given substrate increases the predictability of the resulting surface polymer thickness and surface polymer composition.

[0087] Controllability and predictability of surface polymer formation are related to managing the pH of the reaction composition during surface polymer formation. Thus, increased control and predictability of the surface polymer formation may be facilitated by maintaining the pH of the reaction composition above a pKaH value of the complex formed between the catalyst and the ligand, in particular above the pKaHi of the complex formed between the catalyst and the ligand, above the pKJ / b of the complex formed between the catalyst and the ligand, or between the KaH i and pKJHb of the complex formed between the catalyst and the complex.

[0088] To obtain a desired formed surface polymer thickness, it may be valuable to know when to terminate the surface polymer formation, and to ensure that this termination occurs with a sufficient rate and efficiency. This may indeed be ensured by termination surface polymer formation by quenching the surface polymer formation as described herein. Thereby, further surface polymer formation may be minimized between the withdrawal of substrates and / or subsequent handling of substrates. The quenching should aim at taking place so as to minimize the time interval between the quenching event and the quenching effect. For macroscopic substrates, quenching of surface polymer formation is usually performed by physically removing the substrate from the reaction composition, followed by washing off any remaining reaction composition, thereby minimizing further formation of surface polymers. Such a strategy, however, may be impracticable in cases where high numbers of particularly micro- or nanoscopic materials serve as substrates. In the case of, e.g., liquid-phase surface polymer formations on nanoparticles, the usual strategy for recovering the substrate is centrifugation followed by decantation of the polymer- forming reaction composition and optionally further washing steps. Such a process may extend over several minutes, meaning that the surface polymer formation de facto may continue for a period in addition to the intended period, thus, introducing a discrepancy between the predicted and resulting surface polymer thickness. Thus, it may be desirable to immediately terminate the polymerization no matter the size and shape of the substrate. Quenching of a polymerization formation may take place outside the polymerization bath (the reaction composition) by treating the substrate and any residual reaction composition on the substrate with an acidic substance to quench the surface polymer formation ability of any residual reaction composition on the substrate or within the formed surface polymer. The methods disclosed herein offer an alternative to the known methods of terminating surface polymer formation.

[0089] In Fig. 3, the quenching principle described herein is shown schematically. Following addition of an acidic substance, the quenching effectively minimizes further surface polymer formation.

[0090] The methods disclosed herein allow for reversible quenching, i.e., a quenching process which may become re-initiated by subsequent basification of the previously acidified reaction composition. Hereby, it is possible to control the activity of a given reaction composition in a binary fashion depending on the pH of the reaction composition; at a pH higher than the pH at which the catalyst / ligand complex decomposes, the surface polymer formation will occur, and at or below a pH at which the catalyst / ligand complex decomposes the surface polymer formation will be minimized. As explained above, pKa values of the complex formed between the catalyst and the ligand, are used to find the pH value for quenching and re-initiation, respectively.

[0091] In order to ease reaching such target pH quenching and re-initiation values, buffer systems may be employed which features pKa values at the target pH values (in the range of the pKJb value of the catalyst / ligand complex in question). Amino acids generally have more than one pKa value, one pertaining to a carboxylic acid moiety (lower pKa value), and a second pertaining to a primary or a secondary amine moiety (higher pKa value). Glycine, for instance, exhibits pKa values at 2.35 and 9.60. respectively. These two values are suitable for a reaction composition which may be quenched reversibly; at pH 9.60 and above, the surface polymer formation will occur, and at pH 2.35 or below, the surface polymer formation will be minimized.

[0092] The term “buffer” is defined herein as an agent which, when added to the reaction composition, can within a certain pH range withstand changes in pH during the course of the surface polymer formation. Buffer systems include combinations of a weak acid and its conjugate base, or a weak base and its conjugate acid. Non-limiting examples of buffers are carbonate buffer, glycine buffer, citrate buffer, phosphate buffer, acetate buffer, ammonium buffer, formate, sodium ascorbate / ascorbic acid, and Good’s buffers. Good’s buffers include a wide range of buffers, including MES, PIPES, MOPS, HEPES, CHES, CAPSO and CAPS to mention a few. The buffer may be employed as aqueous solutions or non-aqueous solutions in an amount sufficient to maintain the desired pH. In some embodiments, the buffer may be added as a pure substance.

[0093] The buffer may further be useful during the surface polymer formation in order to facilitate surface polymer formation. Different buffers have different buffering ranges, and in an embodiment the buffer is chosen such that the pH of the reaction composition is above a pKJT value of the catalyst / ligand complex, such as above the pKaH2 value or above the pKaHi value of the catalyst / ligand complex. By way of example, an N-cyclohexyl-2-ammoethanesulfonic acid (CHES) buffer system may be used to maintain a pH value in the interval 8.6-10.0, or a glycine buffer system may be used to maintain pH in the interval 8.6-10.6. By controlling the pH > pKaHi, the surface polymerization rate may be kept high and uniform, and the bulk polymer formation may be kept low. At pKaHi > pH > pKaH2 the rate of the surface polymer formation may be kept stable.

[0094] During and after quenching and / or re-initiation of the surface polymer formation, it may be beneficial to control the concentration of dissolved molecular oxygen in the reaction composition. Thus, an oxygen control agent may suitably be included in the reaction composition. The oxygen control agent may chemically remove O2 dissolved in the reaction composition, thereby controlling the oxygen concentration in the reaction composition. The chemical removal of O2 may suitably be done by a substance with oxygen scavenging properties. Oxygen scavenging is here understood to be the continuous consumption of molecular oxygen which is or becomes dissolved in the reaction composition. It is presently believed that the principal reaction pathway responsible for the beneficial oxygen scavenging is a reduction reaction, that is. the oxygen scavenger may be a substance capable of reducing molecular oxygen dissolved in the reaction composition. Non-limiting examples of oxygen scavengers are sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid.

[0095] Oxygen dissolved in the reaction composition may also be removed physically, e.g., by purging with an inert gas such as argon or nitrogen, by sonicating, or by vacuum degassing.

[0096] The amount of molecular O2 in the reaction composition may be measured and expressed by a partial pressure. A specific partial pressure in hPa relates to a concentration in M through Henry’s law. Information needed to convert a partial pressure p(C>2) to a molar concentration [O2] includes Henry’s solubility parameter (Hscp) for a given species in a given solution (for O2 in H2O at rt, Hscp= 1.3T0’3M atm1), the partial pressure of the species, the temperature of the medium (due to the temperature dependency of equilibrium constants) and ionic strength of the medium (due to a typically decreasing gas solubility at higher salinities). For binary solvent mixtures, the Henry’s law solubility parameter is dependent on the individual Hscpvalues for the individual solvents on their pure form, as well as an interaction parameter of the solvents derived from Wohl expansion of excess chemical potential. (Note: 1 hPa corresponds to 1 mbar.)

[0097] The concentration of O2 (amount of dissolved O2) in the reaction composition is thus related to p(Ch) (the partial pressure of O2) in the reaction composition. For a given reaction composition as defined herein. p(Ch) should in general not exceed 25 hPa. i.e., the oxygen control agent should be added in an amount so as to keep p(Ch) below 25 hPa or at 25 hPa during surface polymer formation. The amount of oxygen dissolved in a reaction composition can be measured in hPa using a sensor with a sensitivity' within this range. Within the present context, the amount of oxygen dissolved in the reaction composition may also be referred to as "‘concentration of O2” or “partial pressure of O2”.

[0098] The amount of O2 dissolved in the reaction composition should in general not exceed 25 hPa in order to maintain stable rate during the surface polymer formation. It is believed this minimizes oxidation of the active catalyst / ligand complex to its oxidized deactivating (inactive) form. Controlling the oxygen concentration affects the equilibrium between the activating catalyst / ligand complex and its oxidized deactivating form and provides an improved control over the rate of surface polymer formation. To initiate the surface polymer formation, the activating catalyst / ligand complexes react with polymerization initiators (attachment of polymerization initiators to the surface is described later) to generate propagating radicals, that undergo polymer formation with monomers. On the other hand, the oxidized deactivating form of the catalyst / ligand complex may react with propagating radicals and form capped dormant species (from which further polymerization does not occur). Dissolved O2 present in the reaction composition will oxidize the activating catalyst / ligand complex to its oxidized deactivating form and thereby change the equilibrium between activating catalyst / ligand complex and the oxidized deactivating form, and thereby hamper surface polymer formation. The catalyst activator on the other hand continuously (re)generate the activating catalyst / ligand complex from the oxidized deactivating catalyst / ligand complex. Due to the high rate with which the activating catalyst / ligand complex may be consumed through oxidation by O2, continuous generation of the activating catalyst / ligand complex facilitated by the catalyst activator may be counteracted by the presence of O2, incapacitating the surface polymer formation which driven by the activating catalyst / ligand complex. Besides, O2 may also react with active radical chain ends (propagating radicals) and quench the polymer formation. Hence, by ensuring the partial pressure of O2 dissolved in the reaction composition does not exceed 25 hPa, stable rate of surface polymer formation may be obtained. Thus, adding excess oxygen control agent may allow for improved control of the surface polymer formation.

[0099] In some cases, the oxygen control agent may react with O2 present in the reaction composition and form H2O2. H2O2 may further react in a metal-catalyzed Fenton-like reaction (see J. Catal. 2013, 301, 54-64.) to generate OH radicals that initiates bulk polymerization in the reaction composition. For surface polymer formation, bulk polymer formation is generally undesirable, as it (a) alters the reaction composition and ultimately may reduce the activity and the lifetime of the reaction composition and (b) increases the likelihood that post-cleaning will be needed due to strong physical binding of the formed bulk polymers to the substrate. By keeping the partial pressure of dissolved oxygen from exceeding 25 hPa, the formation of H2O2 is minimized, and hence also the undesirable bulk polymer formation. An example of a H2O2 generating oxygen control agent is sodium ascorbate in combination with a Cu catalyst. Importantly, in cases where one or more processes in the reaction composition is capable of continuously and rapidly consuming dissolved O2, the reaction composition may be kept and operated under ambient atmosphere which contains O2 with no loss in surface polymerization ability.

[0100] The reaction composition comprises at least one catalyst activator. 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, tin 2-ethylhexanoate, sodium phenoxide, sodium dithionite, and a mixture of iron powder and sodium chloride. The catalyst activator may suitably be added in excess compared to the catalyst. Excess may, e.g., be 10-250 times.

[0101] The oxygen control agent as well as the catalyst activator for the catalyst may be added several times during surface polymer formation and / or quenching or re-initiation, respectively, to control reaction composition conditions.

[0102] The unique reversibility of the quenching described herein allows for reactivating a quenched reaction composition so as to re-initiate surface polymer formation. Thus, a reaction composition may be reused in one or more subsequent surface polymer formation events. In particular, it may be possible to obtain the same average polymer thicknesses on subsequent substrates (given similar polymerization times and polymerization conditions) as before the quenching was performed. As an example, a reaction composition which was quenched by acidification may be brought essentially back to the pH level assumed by the reaction composition before the quenching event through the addition of substance raising the pH, i.e., an alkaline substance. By reverting essentially to the pH value from before the quenching event, the ligand may no longer be protonated, and the catalyst / ligand complex once again may exist as a stable species, and, thus, the continued surface polymer formation may be achievable.

[0103] The reaction composition may further comprise a halide compound for increasing the “livingness” of the surface polymer formation. A “living” polymerization refers to a surface polymer formation where the rate of termination is minor in comparison to the rate of propagation of surface polymer chains (extension of a surface polymer by monomeric units). As a result, living polymer formations show a linear relationship between polymer chain length and time. A living polymer formation also allows for propagating block copolymers. 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, CuBn and CuCh 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 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 effects; (1) a lowering of the rate with which surface polymers grow initially due to a lower number of propagating chains, and (2) a lowering of the rate with which chain termination between two propagating surface polymer chain-end radicals occur (through recombination or disproportionation), leading to an increased living character of the surface polymer formation. In an embodiment, the catalyst is Cu, the ligand is MegTREN, PMDETA, TREN, HMTETA, TMEDA, or Me4Cyclam and the halide compound is NaCl.

[0104] The reaction composition to be used herein comprises at least one solvent. The solvent may be any solvent that provides sufficient solubility’ of the components of the reaction composition. Suitable solvents include but are not limited to: alcohols, dipolar aprotic solvents (for examples, tetra- hydrofuran, 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.

[0105] The solvent used may be aqueous. Thus, the solvent may be a mixture of water and an organic solvent. Suitable solvents include, but are not limited to, alcohols, dipolar aprotic solvents (for example, tetrahydrofuran, methyl acetate, ethyl acetate, butyl acetate, dimethyl sulfoxide, dimethyl formamide), methylene carbonate, ethylene carbonate, propylene carbonate, ethyl lactate alcohol, toluene, ionic liquids, and supercritical CO2. The solvent may be chosen so as to provide sufficient solubility7of the components of the reaction composition. The ratio (volume-% (vol%)) between water and organic solvent may be 10:90, 20:80, 30:70. 40:60, 50:50, 60:40, 70:30, 80:20, or 90:10 as well as range therebetween. In one embodiment, the solvent may be a combination of methanol and water, ethanol and water, or isopropanol and water.

[0106] The monomers for surface polymer formation may be any such desired for the final product.

[0107] Non-limiting examples of appropriate monomer types include anionic, cationic, zwitterionic, protic and aprotic monomers, and include acrylates, methacrylates, halogen-substituted alkenes, acrylamides, methacrylamides, and styrenes, as well as mixtures thereof. The generic monomer structure comprises a polymerizable part (an alkenyl 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.

[0108] For acrylate monomers, non-limiting examples of functional moieties include but are not limited to: alkyl groups, sulfonates, fluorosulfonates, carboxyls, metal carboxylates, ethers, poly(ether) groups, bis(sulfonyl)amides, fluorinated sulfonates, perfluoroalkyl carboxylate, borate, fluorinated borate, borate ester derivatives, tetraphenylborate, bis(trifluoromethane)sulfonimide, triflimides and derivatives thereof, halogenated alkyl chains, and mono-, di-, and tri-alkoxy silanes.

[0109] The polymerizable part and the functional part of monomer can, in certain embodiments, be connected by linker moiety. Non-limiting examples of appropriate linker chemistries include but are not limited to: alkyl chains, esters, ethers, poly(ethers), amines, amides, aryls, and any combination(s) thereof. Non-limiting examples of appropriate acrylate monomers containing alkyl linkers include but are not limited to: methyl acrylate, ethyl acrylate, and lauryl acrylate. Nonlimiting 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. Nonlimiting examples of monomers without linker chemistry’ include but are not limited to: acrylic acid, and lithium acrylate, and sodium acrylate.

[0110] For methacry late 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, sulfonates, fluorosulfonates, bis(sulfonyl)amides, fluorinated sulfonates, perfluoroalkyl carboxylate, borate, fluorinated borate, borate ester derivatives, tetraphenylborate, bis(trifluoromethane)sulfonimide, triflimides, and derivatives thereof, halogenated alkyl chains, and mono, di, and tri-alkoxy silanes.

[0111] 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.

[0112] Non-limiting examples of methacrylate monomers include but are not limited to: methacrylic acid, lithium methacry late, sodium methacry late, methyl methacrylate (MMA), potassium 3-sulfpropyl methacrylate, 2-hydroxyethylmethacrylate (HEMA), glycidyl methacrylate (GMA), ethyl methacrylate. n-butyl methacrylate, tert-butyl methacrylate (tBMA), lauryl methacrylate, (((perfluorobutyl)sulfonyl)oxy)methyl methacrylate and 3-(A-((trifluoromethyl)sulfonyl)sulfamo- yl)propyl methacrylate, 1H, 17 / ,2 / / ,277-heptadecafluorodecyl methacrylate (HFDMA), 2-((tri- ethoxysilyl)oxy)ethyl methacry late, and 2-(3-(triethyoxsilyl)propoxy)ethyl methacrylate.

[0113] Non-limiting examples of acrylate monomers include but are not limited to: methyl acrylate (MA), tert-butyl acrylate ( / BA). laury l acrylate, and 2-hydroxyethylacrylate (HEA).

[0114] Non-limiting examples of appropriate halogen-substituted alkene monomers include but are not limited to: vinyl chloride, vinylidene difluoride, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene.

[0115] Non-limiting examples of appropriate acry lamide monomers include but are not limited to: acrylamide, A-Ao-propylacrylamide, A-tert-butylacrylamide, and A-hydroxyethyl acrylamide (HE Am).

[0116] Non-limiting examples of appropriate methacrylamide monomers include but are not limited to: A-Ao-propylmethacrylamide, methacrylamide, AAm-buly I methacryl ate (tBMA). and JV-hydroxy- ethyl methacrylamide (HEMA).

[0117] Non-limiting examples of appropriate styrene monomers include but are not limited to styrene, 4- methylstyrene, 2,3,4,5,6-pentafluorostyrene, / ?-divinylbenzene. 4-chlorostyrene, sodium 4- vinylbenzenesulfonate. lithium 4-vinylbenzenesulfonate, and 4-vinylphenyl 1, 1,2, 2, 3, 3, 4,4,4- nonafluorobutane- 1 -sulfonate.

[0118] 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 conductivity, and / or permeability. Monomers may be chosen to improve interface stability of a surface in question. Furthermore, introduction of functional groups or combination of functional groups may provide improvement over various desired properties, like density, dielectric constants, diffusion barrier, wettability, etc. Monomers may suitable 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 a reaction medium. In each application, an amount of monomer may be chosen to obtain desired polymerization kinetics, solubility of the monomer, and cost of the monomer. In most cases, the amount of monomer may be in the range of 0.5 vol% to 50 vol%.

[0119] Following formation of the surface polymer, the surface polymer 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-hydroxyethyl methacrylate is denoted HEMA, and after polymerization, the polymer molecule is denoted PHEMA.

[0120] In a particular embodiment of the present disclosure, the surface polymer is a polymer brush. Throughout the disclosure herein, the term “surface polymer’" may also include polymer brush.

[0121] Some methods for preparing a substrate for surface polymer formation have been described in the art. A brief description of the usually used processes is given herein. However, it is to be understood that alternative processes may also be suited and workable within the context of the present disclosure.

[0122] To propagate surface polymer chains from the surface of the substrate, polymerization initiators may firstly be attached to a portion of the surface of interest for surface polymer formation. The attachment process is further described below. The procedures may in general apply to all types of substrates. It is to be understood that modifying a substrate with initiators will generally result in a multiplicity' of initiators being attached to the surface of the substrate. The initiators may be attached to available surface modification sites on the substrate. Prior to attachment of polymerization initiators, the surface of the substrate may be cleaned using various techniques, including sonication in ammonia, ABC-clean A200, a solution of DI-watecNFfcFbCh (5:1 :1), acetone, and / or water. Following attachment of polymerization initiators, the substrate may be annealed at ambient conditions or at elevated temperatures.

[0123] If only specific areas of a material surface are to be exposed to polymerization initiators, the particular area(s) on the surface may be blocked, e.g., chemically or by using a foil, seal or cover, or etched, or masked, protected, or defined by lithographic patterning. Also, anon-polymerization initiator (“dummy” initiator, i.e. a substance that cannot initiate surface polymer propagation) may be used together with the polymerization initiator to “dilute” the attachment of polymerization initiators. “Dummy” initiators may be a substance which is suited for further modification, e.g., attachment of a functional group or moiety. “Dummy” initiators may also be a substance adding certain chemical properties to the resulting substrate with surface polymers.

[0124] 1-step silane grafting:

[0125] Surface modification substances (polymerization initiators and / or “dummy” initiators) may be attached to at least a surface or a portion of a surface in one step by silane grafting of trialkoxysilane with substituted benzyl / benzyl halide or substituted tertiary / tertiary halide groups. Silane grafting is normally performed by vapor deposition, in solution, by spray coating, or painton coating.

[0126] 1-step diazonium grafting:

[0127] Surface modification substances (polymerization initiators and / or “dummy” initiators) may be attached to at least a surface or a portion of a surface in one step by grafting aryl diazonium salts with substituted benzyl groups / benzyl halide groups. The diazonium grafting is normally performed either by activating the aryl diazonium salt electrochemically or chemically or by spontaneous reaction. 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. 2-step diazonium grafting 2-step:

[0128] Another route of initiator attachment is by a 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, the polymerization initiator is attached by performing a nucleophilic acyl substitution reaction with an acid or acid-chloride or -bromide containing a -C-X moiety7(polymerization initiator moiety ) with X being a halogen such as Cl or Br. A ’dummy" initiator is attached by performing a nucleophilic acyl substitution reaction with an acid or acid-chloride or -bromide containing a -C-X moiety (nonpolymerization initiator) with X being H or -CH3. The nucleophilic group may7be subjected to nucleophilic acyl substitution reaction with an acid or acid-chloride or -bromide containing a -C- X moiety with X being Cl, Br, H or CH3 to add polymerization initiator and / or “dummy' initiator’, respectively. The polymerization initiator moiety of the surface modification may be, e.g., benzyl halide, secondary alkyl-halide and tertiary^ alkyl-halide, whereas the non-polymerization initiator may be the same with the halide being substituted by H or CH3.

[0129] 2-step silane grafting:

[0130] The first step in the 2-step silane grafting procedure is grafting of a silane that contains a nucleophilic group (alcohol or amine). In the second step, the polymerization initiator is attached by performing a nucleophilic acyl substitution reaction with an acid or acid-chloride or -bromide containing a -C-X moiety7with X being a halogen such as Cl or Br. A dummy initiator is attached by performing a nucleophilic acyl substitution reaction with an acid or acid-chlonde or -bromide containing a -C-X moiety with X being H or -CHs.

[0131] Other processes for attaching surface modification substances (polymerization initiators and / or non-polymerization initiators) may be applied. An example is the polymerization initiator p- (chloromethyl)phenyltrimethoxysilane (CPTMS) which may be attached using a vapor deposition method or a dipping method. Another example is the polymerization initiator / ?-(chloro- methyljphenyltrimethoxysilane (CPTMS) in combination with the “dummy” initiator (3-glycidyl- oxypropyl)trimethoxysilane (GPTMS), the latter which display an epoxy (epoxide) group suited for further modification by ring-opening of the epoxy (epoxide) group.

[0132] The presence of polymerization initiators on the surface of the substrate may be “diluted” by the simultaneous presence of “dummy” initiators. The “dummy” initiator may be added in a certain percentage together with the polymerization initiator, thus, competing with the polymerization initiator about available attachment sites on the substrate surface. Suitable “dummy'’ initiators include such specified above where X is H or CHs and functional “dummy” initiators as GPTMS mentioned above. Dilution of the polymerization initiator with a “dummy” initiator may be used to adjust the density of the polymerization initiators on the surface of the substrate, thus, aiding in controlling density (“grafting density”, i.e. the number of surface polymer chains per unit area of the substrate) of subsequently formed surface polymers. The density of the initiators (both polymerization initiators and non-polymerization / ”dummy” initiators) influences the density of the subsequently formed surface polymer propagated from the polymerization initiators. As mentioned above, the density7of polymerization initiators is intended to mean the number of polymerization initiators per unit area of the substrate. The density of polymerization initiators to non-polymerization (“dummy”) initiators may be controlled by, e.g., co-grafting of the polymerization initiator and the non-polymerization initiator in varying percentages. Non-limiting examples of suitable percentage ratios (molecular-% (mol%) of polymerization initiator to non- polymerization initiator) may be in the range 100:0 (no non-polymerization initiator), 90: 10, 80:20, 70:30, 60:40. 50:50, 40:60, 30:70, 20:80, and 10:90. The initiator density7affects the morphology of surface polymers formed on the surface, as indicated in Fig. 3.

[0133] Substrates for surface polymer formation are described in the following. 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 polymerization initiators, and secondly formation of surface polymers from said polymerization initiator sites. Suited substrates include, but are not limited to, metal (like aluminum, steel, nickel, gold, silver, platinum, chrome, copper, iron and alloys), glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composites, plastics, semiconductors, compound semiconductors (e.g., GeAs and InP), and particles (e.g., Si, metal, metal alloys and coated particles as well as a combination thereof presented on the same said surface). 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, 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 viewed as one (nano)particle. Formation of surface polymers:

[0134] Surface polymer is then grown or formed from the surface-attached initiators upon contact with a reaction composition as defined.

[0135] Surface polymer thickness may be of any thickness. By way of example, e.g., from 1-1.000 nm. The thickness of surface polymer may depend on the specific intended application and may be from 1-500, 1-250 nm, 5-100 nm, 120-250 nm, 10-80 nm, or 10-30 nm thick, measured as the dry film thickness of collapsed surface polymer. The thickness refers to the dry film thickness of surface polymer formed. The dry' film thickness is dependent on the density' (anchoring points per area) of end bonded polymer chains and the length of the individual chains.

[0136] In certain embodiments, surface polymer layer can possess specific properties obtained through block co-polymers, random polymers, or binary mixed polymer, where two or more disparate monomers are used to grow the surface polymer in different surface polymer architectures. In such embodiments the individual components (different monomers) of block co-polymers. random polymers or binary mixed polymers can contribute different properties resulting in a surface polymer with a combination of desired properties.

[0137] Surface polymer layer can be applied or formed by repeating certain of the above steps to build up block co-polymers from chain end alkyl halide units of the formed surface polymer. The same or different monomers can be applied relative to the monomers used to form previous layers. Forming additional layers of surface polymer can be repeated multiple times to obtain a more complex or thicker surface polymer. Surface polymers can also be formed using two or more different monomers propagates from one type or different types of initiators thereby forming random or mixed surface polymers, respectively. 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.

[0138] For forming surface polymers, the substrate and the reaction composition are typically kept in contact with each other for a suitable period (residence time), sufficiently to form surface polymers essentially having an average dry film thickness within a desired range. The residence time may be as long as needed. Suited residence times include, but is not limited to, up to 24 hours, e g., 2 seconds, 5 seconds, 10 seconds, 20 seconds. 30 seconds, 40 seconds, 50 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 include, but are not limited to, such from 5 °C up to 120 °C, such as from room temperature (approximately 20°C) to 120°C. Specific temperatures include, but are not limited to, 5°C 10°C, 15°C, 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. 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 dry ing.

[0139] As used herein, the terms “a substrate7’ and “the substrate” are intended to include both a single substrate and a plurality of substrates in any form and shape.

[0140] Surface polymers may suitably be formed on a portion of a substrate or on all surfaces available on a substrate. Surface polymers may be formed on available surfaces at the same time (e.g.. in the case of single-piece substrates) or on available surfaces in a sequential manner (e.g., in the case of reel-to-reel processing of fibers, threads, wires etc.).

[0141] In accordance with an aspect of the present disclosure there are provided systems for forming the aforementioned surface polymers on a poly merization initiator-modified substrate. In other words, on a substrate that has been treated with a polymerization initiator, thus, forming polymerization initiating sites on at least a portion of the substrate. For example, a surface of the substrate on which it is desired to form the aforementioned surface polymers, has been subjected to polymerization initiator modification. The polymerization initiators enable surface polymers to form on the substrate when it is subsequently brought into contact with the aforementioned reaction composition. For present purposes it is immaterial where the polymerization initiators are applied to the substrate, provided that this is done prior to bringing the substrate into contact with the reaction composition. In some embodiments it is envisaged that the substrates may be precoated with the polymerization initiator and provided to the system comprising the polymerization initiator coating. In other embodiments it is envisaged that application of the polymerization initiator coating may occur within the system, and suitable apparatus may be provided to achieve this where needed. Fig. 6 is a non-limiting schematic illustration of a system 100 for forming surface polymers on at least a portion of a substrate. The system 100 comprises a reaction composition container 104 containing the aforementioned reaction composition 105. Container 104 may relate to any vessel or chamber suitable for holding the reaction composition. At least a portion of a polymerization initiator-modified substrate 102 is brought into contact with the reaction composition 105, for example by at least partly immersing a desired surface of substrate 102 into the reaction composition, thereby enabling surface polymers to form on the substrate.

[0142] Optionally, system 100, may comprise one or more further containers, each container comprising different compositions and / or agents for treating the substrate 102, either prior to the substrate being brought into contact with the reaction composition 105, or afterwards. For example, where substrate 102 has not been pre-treated with a polymerization initiator, then the system 100 may further comprise a container 106 holding a polymerization initiator chemi stry 107, thus, forming the polymerization initiator-modified substrate 102 in the container 106. In another example, substrate 102 is removed from the reaction composition 105 and moved to container 109 holding a quenching solution 111 for quenching the surface polymer formation as described herein. Furthermore, according to an aspect of the invention, the quenching solution may be provided to the surface of the substrates by a spray fixture in container 109.

[0143] Fig. 6 relates to an embodiment in which the substrate has been pre-coated with a polymerization initiator. In such embodiments, and as illustrated in Fig. 6, a cleaning container 114 may be provided, comprising a cleaning agent or cleaning device 116. The cleaning agent / device 116 may be used to clean the surface of substrate 102 prior to bringing it into contact with reaction composition 105 held by the reaction composition container 104. This may be achieved by, at the very least, subjecting at least a portion of the substrate 102 on which it is desired to form surface polymers on, to cleaning procedures in container 114 using cleaning agent / device 116. In this w ay, any impurities which may interfere with the formation of the surface polymers, are removed from the surface of substrate 102, prior to bringing substrate 102 into contact with the reaction composition 105. System 100 may additionally include a substrate displacement device 103 for bringing the substrate 102 at least partly into contact with the reaction composition 105 held by the reaction composition container 104 for a controlled time to ensure surface polymers form. The displacement device 103 may be used to remove the substrate 102 from the reaction composition 105 following surface polymer formation. Thus, the substrate displacement device 103 may be configured to maintain the surface of substrate 102 at least partly in contact with the reaction composition 105 to enable surface polymers to form on at least a portion of the surface of the substrate, and the substrate displacement device 103 may be configured to maintain the substrate 102 in contact with the reaction composition 105 for a predetermined amount of time. However, it may be required to have a more precise control over when surface polymer formation is stopped, and the surface polymer formation reaction may be stopped by chemical quenching by changing the pH of the reaction composition as described herein. Furthermore, in some embodiments it may not be sufficient to have surface polymer formation begin immediately when a substrate is placed in the reaction composition 105 - this may be due, for example, to the need to wait for air bubbles to be removed from the substrate and substrate holder surfaces, using agitation, ultrasonic agitation, or other means, prior to beginning surface polymer formation. Therefore, the reaction composition may be set at a pH where the surface polymer formation reaction does not proceed (at a pH below pKaH2 for the complex formed between the catalyst and the ligand) and the reaction is initiated at a desirable time after the substrate has been placed in the reaction composition by increasing the pH of the reaction composition above pKaH2. Furthermore, in some embodiments by controlling the pH of the reaction composition the surface polymer formation reaction can be quenched for a first substrate prior to removal from the reaction composition 105 and then the reaction can be re-initiated prior to placing a second substrate in the reaction composition 105.

[0144] In embodiments where the system 100 may comprise two or more containers, such as illustrated in Fig. 6, in addition to bringing substate 102 into contact with the compositions contained by each container, the substrate displacement device 103 is configured to transport substrate 102 to and from each container. For example, as illustrated in Fig. 6, the substrate displacement device 103 is configured to first transport substrate 102 into contact with cleaning agent / device 116 in container 114, and / or a polymerization initiator composition 107 if the substrate is not pre-coated with a polymerization initiator as mentioned previously, held in the polymerization initiator container 107, and subsequently to transport the substrate 102 from the poly merization initiator container 107 to the reaction composition container 104, where the substrate is brought at least partly into contact with the reaction composition 105 held by the reaction composition container 104. In the latter example, the substrate may in embodiments be cleaned between initiator coating and surface polymer formation. The substrate displacement device 103 may relate to any device capable of transporting the substrate from one container to another container. For example, the substrate displacement device 103 may relate to a mechanical device. In particular, it is envisaged that the substrate displacement device 103 may comprise any one of: a conveyor system; a programmable mechanical arm; and / or a roll-to-roll processor / mechanism.

[0145] A conveyor system as used herein may refer to a mechanical system that is used to move a material, such as the substrate, which in embodiments may be in a substrate holder on its own or with other substrates, from one process container to another, typically comprising a movable conveyor, powered by a drive system and having a series of rollers or pulleys that support and guide the belt. In use, the substrate may be placed on the conveyor which passes the substrate through the one or more containers comprised in the system. In this way, as the conveyor is powered, the substrate is passed through the component(s) held by each container within the system.

[0146] In some embodiments a programmable mechanical arm, such as a robotic arm, may be used to transport the substrate, which may be in a holder as described above.

[0147] In some embodiments the substrate may be a nanoparticle material in which case a special holder may be utilized for containing the particles within the volume of the particle holder - so the particles do not disperse throughout the reaction composition container 104 and become difficult to remove. In further embodiments, the nanoparticle material may be collected from reaction composition using a centrifuge or separated through a membrane.

[0148] A roll-to-roll processor or mechanism is particularly advantageous for use where the substrate may be flexible and elongated, such as a cable, wire, foil, or any other elongated flexible substrate. Fig. 7 illustrates such an embodiment, in which the substrate displacement device relates to a roll-to- roll processor 118, comprising a sending roll 121, a receiving roll 122 and a plurality of rollers 120. At least some of the rollers 120 and the receiving roll 122 are driven, thereby enabling a flexible elongated substrate 123 to be passed from sending roll 121 through the reaction composition 105 in container 104 to the receiving roll 122. The roll-to-roll mechanism can be utilized as a replacement to the substrate displacement device 103 in FIG. 6 when elongated flexible substrates are being processed. Being able to quench and re-initiate the surface polymer formation reaction may be useful should the roll to roll feed of processor 118 stop and need to be started again, since the reaction can be stopped by quenching for the period when the roll-roll mechanism is not operating and re-initiated when the mechanism restarts.

[0149] In yet further embodiments, at least one of the plurality of containers may comprise an annealing oven for annealing the formed surface polymers. In a similar manner as described previously, the substrate displacement device 103 may be configured to transport the substrate with the formed surface polymers to an annealing oven 109 and to bring the substrate with surface polymers into position for annealing. The annealing oven is equipped with a heating device for annealing the formed surface polymers and a gas environment 111 in the oven may be controlled as needed - for example, to avoid oxidation by using only non-oxidizing gases.

[0150] Fig. 10 is a more detailed schematic illustration of the reaction composition container 104 containing the reaction composition 105 of Fig. 6 or Fig. 7, in accordance with an embodiment. The reaction composition container 104 may be equipped with one or more sensors. The one or more sensors may be configured to measure a characteristic of the reaction composition 105, which characteristic may relate to a physical or chemical characteristic of the reaction composition 105, such as the pH of the reaction composition or the molecular oxygen concentration in the reaction composition. The sensor data may be used to determine whether a value of the measured characteristic lies within a predetermined threshold for the surface polymer formation process, such as initiation, quenching and reinitiation. If the measured characteristic is determined to lie outside the predetermined threshold, then the chemistry of the reaction composition may be adjusted by dispensing a polymerization control agent into the reaction composition to adjust the value of the measured characteristic. In this way, it is possible to ensure that the values of the one or more characteristics of the reaction composition are within a range suitable for forming surface polymers on the substrate. A control unit operatively connected to the one or more sensors, may be used to control one or more dispensers for dispensing one or more control agents to control the chemistry of the reaction composition, for example a rise in pH can be corrected by dispensing acid into the reaction composition 105 in the container 104. The measured characteristic may relate to any one of the aforementioned physical or chemical characteristics of the reaction composition. Furthermore, the control unit 210 can be used to shift the pH of the reaction composition 105 to either quench, initiate, or re-initiate the surface polymer formation reaction by instructing the pH control agent dispenser to dispense appropriate acid or base and using feedback from the pH sensor 216 to determine the correct dose of the acidic substance or the alkaline substance to use. Furthermore, the system of Fig. 10 may be used for providing pH control to the quenching container 109, when the quenching process is physically separate from the formation process of surface polymers.

[0151] Similarly, the chemistry of the reaction composition may be adjusted by dispensing any one or more of the components of the reaction composition into the reaction composition. For example, the components may relate to any one or more of: at least one monomer, at least one ligand, at least one catalyst, at least one catalyst activator, and at least one solvent. In some embodiments, the control unit may be configured to output a control signal for controlling operation of a dispenser for dispensing one or more components of the reaction composition into the reaction composition, in response to the measured characteristic of the reaction composition, or in response to an observed time variance of the characteristic. For example, a value of the measured characteristic may be monitored over a time period using the one or more sensors. The control unit may determine to output a control signal to control operation of one or more dispensers to dispense the one or more components on the basis of an observed variation over time of the measured characteristic. The observed variation may be indicative that the chemi stry of the reaction composition is varying such that the surface polymer formation process is falling out of specification - for example, surface polymer formation is reduced and / or compromised. The dispensing of one or more components of the reaction composition into the reaction composition may help to maintain one or more chemical properties of the reaction composition, to enable the formation of surface polymers.

[0152] In some embodiments, dispensing of the one or more control agents and / or components of the reaction composition may occur periodically. In such embodiments, sensor measurement data may be used to ensure the chemical and / or physical characteristics of the reaction composition are as desired. However, dispensing of the one or more control agents and / or components of the reaction composition, and more specifically the outputting of one or more control signals by the control unit to control the dispensers, may be independent of any specific sensor measurement. (The latter method of maintaining the reaction composition can be based on known rates of consumption of components of the reaction composition or on known variation over time of pH or molecular oxygen concentration, for example.) In yet further embodiments, dispensing of the one or more control agents and / or components of the reaction composition, and more specifically the outputting of one or more control signals by the control unit, may be directly dependent on one or more measured characteristics of the reaction composition. Similarly, the outputting of one or more control signals by the control unit to control dispensing of the one or more control agents and / or components of the reaction composition may be dependent on a measured sensor signal indicative of a change in a measured characteristic of the reaction composition. Combinations of some of these different methods may also be advantageous, for example using dispensing of agents and / or components for maintenance of the reaction composition over shorter time intervals without use of sensor measurements, combined with adjustments being made based on regular sensor measurements made at longer time intervals.

[0153] Furthermore, the outputting of one or more control signals by the control unit may implement surface polymer formation initiation, quenching or reinitiation as described herein.

[0154] For non-limiting purposes only, the illustrated examples in Figs. 8 through 10 illustrate embodiments where the control unit outputs one or more control signals for controlling one or more dispensers, dependent on a measured sensor signal indicative of a predetermined threshold value associated with a characteristic of the reaction composition not being met, or dependent on a change in pH required to initiate, quench or reinitiation the surface polymer formation process.

[0155] With reference to Fig. 10 and in accordance with some embodiments, the reaction composition container 104 may comprise a pH sensor 216 operatively coupled to a control unit 210. The pH sensor 216 may consist of a probe or electrode that is inserted into the reaction composition 105 to be measured. The pH sensor 216 and control unit 210 may be used to determine if the pH of the reaction composition 105 is within a suitable range for surface polymer formation. For example, the control unit 210 may be programmed to determine if the pH value of the reaction composition measured by the pH sensor 216 is below a predetermined threshold at which surface polymer formation can still take place. In some embodiments, the pH threshold may be selected as being equal to or greater or lower than a pKaH value of the catalyst ligand complex used in the reaction composition 105. For example, in some embodiments the predetermined pH threshold value may be equal to or greater than the pKaHi value of the catalyst ligand complex. In some embodiments the predetermined pH threshold value may be equal to or greater than the pKaFb value of the catalyst ligand complex. In some embodiments the predetermined pH threshold value may be equal to or lower than the pKaH2 value of the catalyst ligand complex. In yet further embodiments, the pH threshold may relate to a suited range, for example, less than or equal to pKaHi and greater than or equal to pKJD.

[0156] The control unit 210 may be configured to control the operation of one or more chemical agent dispensers 202. 204. For example, one of the dispensers may relate to a pH control agent dispenser 202, configured to dispense a volume of pH control agent 106 into the reaction composition 105. The control unit 210 may control the operation of the one or more dispenser 202, 204 via one or more output control signals. For example, the pH control agent dispenser 202 may be configured to dispense the pH control agent 206 into the reaction composition 105 dependent on receipt of a pH control signal from control unit 210. Control unit 210 may be configured to output the pH control signal when a pH sensor signal indicative of the pH of the reaction composition 105 being below the predetermined threshold is received by the control unit 210. Adding a pH control agent to the reaction composition 105 adjusts the pH of the reaction composition 105. In this way, by adding pH control agent to the reaction composition 105 when the pH changes relative to the threshold value, it is possible to control the pH of the reaction composition 105 and to ensure that it remains in a range suitable for format on of surface polymers on substrate 102 with the desired kinetics.

[0157] In some embodiments, the reaction composition container 104 may also comprise a molecular O2 sensor 218 operatively coupled to a control unit 210. The molecular O2 sensor 216 may consist of a probe or electrode that is inserted into the reaction composition 105 to be measured. The molecular O2 sensor 218 and control unit 210 may be configured to determine if the molecular oxygen concentration of the reaction composition 105 is above a predetermined threshold value. The predetermined threshold value may be chosen as the molecular oxygen concentration threshold above which the reaction composition’s 105 ability’ to form surface polymers is compromised. For example, in some embodiments the threshold value may be less than or equal to 25 hPa. The molecular O2 sensor 218 may be operatively coupled to the control unit 210 in a similar manner to the pH sensor 216. Control unit 210 may be configured to output an oxygen control signal to an oxygen control agent dispenser 204, when the molecular O2 sensor signal indicative of the molecular oxygen concentration of the reaction composition 105 being greater than the predetermined threshold is received by the control unit 210 from the molecular O2 sensor 218. Dispensing an oxygen control agent, such as any one of those mentioned herein (e.g. sodium ascorbate), into the reaction composition 105 helps to reduce the molecular oxygen concentration within the composition. By selectively dispensing an oxygen control agent into the reaction composition 105 when the molecular oxygen concentration exceeds a desired threshold value, it is possible to maintain the molecular oxygen concentration of the reaction composition 105 within the desired range, which facilitates the formation of surface polymers and the stable kinetics of the surface polymer formation.

[0158] With reference to Fig. 10 and in accordance with some embodiments the reaction composition container 104 may comprise a recirculation circuit 211 including a pump, or other device to provide efficient mixing of the reaction composition to help ensure any dispensed control agents are more uniformly distributed in the reaction composition 105 and around the substrate(s). In other embodiments, other mechanical or ultrasonic mixing may be applied. The recirculation circuit may comprise a filter for removing particulates and bulk polymer should they be present in the reaction composition; in other embodiments, filters may be positioned in parts of the container other than the recirculation circuit, where there is a good circulation of reaction composition.

[0159] Fig. 8 is a process flow chart illustrating an exemplary method that may be carried out, in accordance with an embodiment, by control unit 210 of Fig. 10 to control operation of the pH control agent dispenser 202. A pH sensor signal is received by control unit 210, at step 302. If the pH sensor signal is determined, at step 304, as being indicative of the pH of the reaction composition 105 being less than the predetermined pH threshold value, as recited previously, then control unit 210 generates and outputs a pH control agent dispenser trigger signal, at step 306. In turn, this causes the pH dispenser 202 to dispense the pH control agent into the reaction composition 105, at step 308. In some embodiments it is envisaged that control unit 210 may receive pH sensor signals on a periodic basis. Accordingly, in such embodiments if it is determined, at step 304, that the received pH sensor signal is not indicative of the pH of the reaction composition 105 being below the pH threshold, then control unit 210 simply waits for receipt of a pH sensor signal indicative of the pH being below the threshold to control operation of the pH control agent dispenser 202.

[0160] Steps 302 through 308 may be iteratively repeated until the measured pH of the reaction composition 105 is greater than or equal to the predetermined pH threshold value. For example, in certain embodiments the pH control agent dispenser 202 may be configured to dispense a predetermined dose (e.g., volume) of pH control agent upon receipt of the first control signal from control unit 210. However, in some scenarios, multiple doses of pH control agent may be needed to increase the pH of the reaction composition 105 to the pH threshold value or more, in which case steps 302 through 308 are iteratively repeated until a sufficient number of doses of pH control agent have been dispensed into the reaction composition 105 to reach the pH threshold value or more.

[0161] Fig. 9 is a process flow chart illustrating an exemplary method that may be carried out, in accordance with an embodiment, by control unit 210 of Fig. 10 to control operation of the oxygen control agent dispenser 204. An O2 sensor signal is received by control unit 210, at step 402. If the received O2 sensor signal is determined, at step 404, as being indicative of the molecular oxygen concentration of the reaction composition 105 being greater than the predetermined oxygen threshold value, as disclosed previously, then control unit 210 generates and outputs an oxygen control agent dispenser trigger signal (e.g., the second control signal), at step 406. In turn, this causes oxygen control agent dispenser 204 to dispense the oxygen control agent 208 into the reaction composition 105, at step 408. If it is determined, at step 404 that the molecular oxygen concentration is not above the predetermined threshold, then control unit 210 simply waits for receipt of an O2 sensor signal that is indicative of the molecular oxygen concentration being greater than the predetermined threshold value to control operation of the oxygen control agent dispenser 204.

[0162] In a similar way as disclosed in relation to Fig. 8, steps 402 through 408 may be iteratively repeated until the measured oxygen value of the reaction composition 105 is less than or equal to the predetermined molecular oxygen concentration. In some embodiments, oxygen control agent dispenser 204 may be configured to dispense a predetermined dose (e.g., volume) of oxygen control agent 208. In some scenarios it is envisaged that multiple doses of oxygen control agent 208 may need to be dispensed to reduce the molecular oxygen concentration of the reaction composition 105 to the predetermined molecular oxygen concentration or less, in which case steps 402 through 408 may be repeated until a sufficient number of doses have been dispensed to reduce the molecular oxygen concentration of the reaction composition 105 to the predetermined molecular oxygen concentration or less. In some embodiments, the oxygen control agent dispenser 204 may be configured to dispense a predetermined dose of oxygen control agent 208 into the reaction composition 105 at predetermined times, e.g., when a substrate is brought into contact with the reaction composition 105.

[0163] In some embodiments it is envisaged that the control unit may be configured to output dispenser control signals as the value of the relevant measured characteristic of the reaction composition approaches the predetermined threshold value. This enables the relevant control agent to be dispensed into the reaction composition before the value of the relevant characteristics falls outside the predetermined threshold.

[0164] In some embodiment the control agent dispensers may be configured to implement a variable dosing regimen in which, for example, the dose of control agent to be dispensed is proportional to the measured value of the characteristic of the reaction composition.

[0165] Whilst Figs. 8 and 9 disclose embodiments in which monitoring of the oxygen and pH characteristics of the reaction composition occur independently, it is to be appreciated that the plurality of characteristics of the reaction composition may be monitored in combination. Furthermore, it is to be appreciated that the dispensing of control agents into the reaction composition may impact two or more characteristics of the reaction composition. For example, dispensing of an oxygen control agent may impact the pH of the composition, and similarly dispensing of a pH control agent may impact the molecular oxygen concentration of the reaction composition.

[0166] In some embodiments it may be advantageous to control the environmental conditions in which the system is implemented, and in particular in which the surface polymers are formed. For example, this may help to reduce contaminants and other impurities contaminating the reaction composition and / or the substrate. Similarly, controlling environmental conditions such as, but not limited to, pressure, temperature, humidity, and / or inert atmosphere, may be beneficial to the process for forming surface polymers. To achieve this, in some embodiments, the system may be implemented in an environmentally controlled chamber. For example, the aforementioned containers may sit within one or more environmentally controlled chambers. In some embodiments all of the containers may sit within one or more chambers. In some embodiments a subset of the containers may sit within one or more chambers. For example, it is envisaged that in some embodiments the polymerization initiator container may sit within a chamber, whilst the reaction composition container, may sit outside a chamber. Similarly, in some embodiments it is envisaged that cleaning of the substrate prior to polymerization initiator formation may also occur in an environmentally controlled chamber, in which case the associated cleaning agent container also sits within an environmentally controlled chamber.

[0167] Whilst the system of Fig. 6 is illustrated as comprising four containers comprising a reaction composition, a cleaning agent or cleaning device, initiator chemistry and an annealing oven it is to be appreciated that the system may comprise any number of containers, more or less than shown, comprising a plurality of different components and / or agents for treating the substrate. In particular, it is envisaged that the system may comprise a plurality of containers comprising a plurality of cleaning agents. Similarly, the system may comprise one or more annealing containers, configured to anneal the substrate at different stages in its processing, that is prior to attachment of polymerization initiators, prior to surface polymer formation and / or subsequent to surface polymer formation.

[0168] In accordance with some embodiments, both cleaning and / or annealing containers may be positioned to treat the substrate at different stages, including for example prior to or after polymerization initiator application, and prior to or after surface polymer formation.

[0169] Fig. 11 is an exemplary process flow chart illustrating the different stages at which the substrate may be cleaned and / or annealed. The system may comprise an initial cleaning stage in which the substrate is cleaned by bringing it into contact with a cleaning agent or cleaning device comprised in a cleaning container, as described previously, at step 501. Examples of cleaning agents include HF and piranha solution to chemical etch surface oxides and organic contaminants; organic solvents to remove organic contaminants, by-products, and residual process chemicals; and water, acids, and bases to remove inorganic contaminants, by-products, and residual process chemicals. Examples of cleaning devices include ovens and vacuum ovens for thermal cleaning; ultrasonic baths for ultrasonic cleaning; electro-cleaning devices; and spray cleaning devices. This may be followed by the application of polymerization initiators to the portion of the substrate on which it is desired to form the surface polymer, at step 503. This may be achieved, as described previously, by bringing the portion of the substrate on which it is desired to form the surface polymers into contact with a polymerization initiator agent, for example vaporized initiator or a solution containing an initiator. Once the polymerization initiators have been formed, the polymerization initiator-modified substrate may optionally be cleaned, by bringing it into contact with a cleaning agent, at step 505; and / or may be optionally annealed, at step 507. Annealing may be carried out as described previously. At step 509, the portion of the substrate on which it is desired to form the surface polymers may be brought into contact with the reaction composition to form surface polymers on the desired portion of the substrate, which may involve initiation, quenching or reinitiation of the surface polymer formation as described previously. Following the formation of the surface polymers on the portion of the substrate, the substrate, and more specifically the formed surface polymers may be optionally cleaned, using a cleaning agent, at step 511; and / or may be optionally annealed, at step 513. Accordingly, the system configured to cany7out all the steps of Fig. 11 may comprise a plurality of cleaning containers each comprising a cleaning agent; a plurality of annealing containers equipped with annealing components / devices. Accordingly, it is to be appreciated that the process of cleaning and / or annealing the substrate may occur before and / or after polymerization initiation; and before and / or after surface polymer formation. The system configured to carry out all the steps of Fig. 11 may further comprise separate containers for surface polymer formation and surface polymer quenching, as described herein.

[0170] In yet further embodiments, it is envisaged that the cleaning agent may be applied to the desired portion of the substrate using an applicator, such as, but not limited to, a spraying device. In such embodiments, it is envisaged that the substrate displacement device may be configured to simply bring the substrate into range of the applicator, such that the applicator may apply the cleaning agent to the desired portion of the substrate. The applicator may be connected to a reservoir containing the cleaning agent.

[0171] In accordance with some embodiments, the system may comprise one or more additional containers containing compositions for forming one or more additional layers or blocks of surface polymers on the substrate. Accordingly, it is envisaged that each layer or block of surface polymer formed on the substrate may be formed by bringing the desired portion of the substate into contact with a reaction composition comprising a different monomer. In this way multiple layers of surface polymer may be formed. The different layers may relate to the same surface polymers, in which case the different containers may contain reaction composition with same monomer, or the different layers may relate to different surface polymers, in which case the reaction compositions held in the different containers contain monomer different from the first. In some embodiments, so-called random surface polymer may be formed. Random surface polymer can be formed applying a reaction composition with multiple different monomers. Random surface polymer may be formed either as first surface polymer layer or further surface polymer layer.

[0172] Some embodiments may comprise a post-treatment container containing a post-treatment agent, and wherein the substrate displacement device is configured to bring the desired portion of the substrate into contact with the post-treatment agent. In some embodiments, post-treatment may comprise post-treatment of formed surface polymers, to convert certain chemical functional groups in surface polymers to other chemical functional groups or to crosslink chemical functional groups in a surface polymer to chemical functional groups in a neighboring surface polymer. Examples of relevant chemical reactions in the post-treatment include deprotection of a protected carboxylic acid, nucleophilic substitution, ring-opening reactions, and anion exchange. In other embodiments, post-treatment may comprise infusion with nano- or micro-particles into the surface polymers. Nano- and microparticles may be inorganic species.

[0173] In some embodiments, the system may comprise a drying device configured to dry the substrate prior to or after bringing the substrate into contact with the compositions held in any one of the containers comprised in the system. The drying may be achieved, e.g., by air blowing or by heating.

[0174] Some embodiments may comprise an etching container containing an etching agent, and wherein the substrate displacement device is configured to bring the desired portion of the substrate into contact with the etching agent. In some embodiment, etching may comprise an etching device for etching patterns on the substrate. Etching may suitably be by plasma etching or HF etching.

[0175] In yet further embodiments, the containers comprised by the system may comprise one or more devices for performing measurements or metrology on the substrate prior to or following each procedure in the surface polymerization, and in particular on the formed surface polymers. Such measurements include, but are not limited, to any one or more of: measuring, removing and analyzing by-products and / or reaction composition components, measuring thickness of the formed surface polymers, and / or measuring the size of particulate bulk polymers formed by filtering off bulk polymers. In accordance with some embodiments, the reaction composition container may comprise one or more further sensors configured to measure characteristics of any one of the following components of the reaction composition: solvent, monomer, ligand, catalyst, catalyst activator.

[0176] In accordance with some embodiments, the system may comprise a plurality of reaction composition containers configured in parallel, such that a plurality of different substrates may be prepared with surface polymers in parallel.

[0177] In some embodiments, the reaction composition container may comprise a recirculation device, configured to circulate components of the reaction compositions, in particular during and / or after dispensing of the one or more polymerization control agents. This may improve the dissemination of the polymerization control agent within the reaction composition. See for example recirculation circuit 211.

[0178] Further examples of sensor that may be provided in the reaction composition container are: conductivity measuring devices, turbidity measuring devices, electrochemical measuring devices, potentiostatic devices. Furthermore, the reaction composition container may further be provided with any one or more of the following devices: ultrasonication devices, temperature controlling devices, UV light generating devices, inert atmosphere generating devices, IR light generating devices. Such devices may assist in monitoring, controlling and / or optimizing the formation of surface polymers on the substrate. Furthermore, the reaction composition container may be configured with one or more dispensers configured to dispense any agent for supplementing reagents (e.g., monomer, ligand, catalyst, catalyst activator, and / or solvent) in the reaction composition. Such dispenser may in some cases comprise a mixing station for mixing prior to dispersing any solutions into a container. One or more sensors may also be incorporated to measure different parameters.

[0179] The one or more containers may comprise a sealing device (e.g.. a lid) for reducing evaporation of the held compositions, and / or reducing possible interaction with the ambient atmosphere. The one or more containers may comprise means for inert gas purge to reduce explosion risks or minimize interaction of the various compositions with the ambient atmosphere. The inert gas purge may, e.g., be applied through a bubbler to increase dew points. Any one of the containers may comprise sample ports for taking samples of the compositions held in the containers for analysis using external equipment.

[0180] Some methods for preparing a substrate for surface polymer formation have been described in the art. A brief description of the usually used processes is given herein. However, it is to be understood that alternative processes may also be suited and workable within the context of the present disclosure.

[0181] Examples

[0182] Example 1

[0183] Pre-cleaning of silicon wafers

[0184] This example describes a procedure for pre-cleaning of substrates for surface polymer formation. One or more substrates may be pre-cleaned according to the procedure described.

[0185] Silicon wafer substrates (r = 5.08 cm, cut to 1 / 4thof a wafer. Test CZ-Si wafer, 4 inch, thickness = 525 ± 25 pm, (100), p-type (Boron), purchased from MicroChemicals GmbH) were cleaned prior to further processing using the following method:

[0186] Racks containing the substrates were placed in an aqueous solution of ammonia (15 vol% DI- water / 85 vol% ammonia, commercially available, 25% p. a. from Chemsolute, cleaning liquid) and sonicated for 10 minutes. Then, the substrates were flushed with Dl-water and sonicated in DI -water for 10 minutes. Thereafter, the racks containing the substrates were transferred to a 5% solution of ABC clean A200 (from ABC-Clean ApS) and sonicated for 10 minutes at in a Bandelin Sonorex Super RK100 sonicator (35 kHz ultrasound frequecy, 80 W nominal ultrasonic power). This step was followed by flushing the substrates in Dl-water (conductivity <0.5 pS) and sonicating the substrates in Dl-water for 5 min with previously described equipment. Finally, the substrates were flushed with acetone (>99%, Chemsolute), and left to dry at room tempera- ture / ambient pressure. Example 2

[0187] Chemical vapor deposition of (p-chloromethyl )phenyltrimethoxy silane (CPTMS)

[0188] This example illustrates a procedure for covalently attaching polymerization initiators to a substrate. One or more substrates may be subjected to the procedures described below.

[0189] Silicon wafer substrates, cleaned as described in Example 1, were used for surface modification with (p-chloromethyl)phenyltrimethoxysilane (CPTMS) polymerization initiators using a chemical vapor deposition method.

[0190] The substrates were placed in a rack and placed in a vacuum oven (Faithful Vacuum Drying Oven- DZ-BCII) with 16 vials of 100 pL CPTMS (polymerization initiator liquid, commercially available, 95% grade from Gelest) at approximately 45°C for 150 minutes. The gauge pressure was lowered to -1.0 bar, whereby the CPTMS evaporated, and the substrates were left for 150 minutes. Thereafter, the substrates were removed and placed in an oven (Binder model FD 56) at approximately 80°C for 5 minutes to anneal the silane layer. The surface modification was verified using water contact angle (WCA) analysis on a Krtiss Mobile Surface Analyzer. The water contact angle (WCA) for both blank Si and CPTMS modified Si are provided in Table 2. Compared to the blank Si substrate the CPTMS modified substrate displays an increased WCA, indicative of an increased hydrophobicity caused by the successful installation of the organic CPTMS layer.

[0191] Table 2. Water contact angles of untreated and surface modified substrates.

[0192] Example 3

[0193] Preparation of a reaction composition for surface polymerization

[0194] This example illustrates the preparation of 1000 mL of a reaction composition.

[0195] To a glass container (container A) was added 16 ml copper / ligand catalyst solution consisting of tris[2-(dimethylamino)ethyl]amine (MeeTREN, 76 pL, >98% grade from abcr or Alfa Aesar), DI- water (15.924 mL), and Cu(II) (324 mg / L, obtained from a solid copper source). To this solution was added a solvent system consisting of Dl-water (484 mL) and ethanol (410 mL, 96% grade from KiiltoClean). Container A was sonicated for 1 minute to reduce air pockets in solution. In a separate glass container (container B), sodium ascorbate (4.00 g. >98% grade from Sigma- Aldrich) was dissolved in Dl-water (15 mL). The content of container B was mixed into container A. After 5 minutes to activate the catalyst / ligand complex, a monomer consisting of methyl methacrylate (MMA, 75 mL, 99% grade containing <30 ppm MEHQ, from Sigma- Aldrich) was added to container A. The liquid was ready to use for surface polymer formation.

[0196] Example 4

[0197] Preparation of a reaction composition with a glycine buffer for surface polymer formation

[0198] This example illustrates the preparation of 1000 mL reaction composition containing a buffer. Buffers were chosen so as to be soluble in the used solvent system. The employed buffer may be chosen such that its coordination to copper is much weaker than the employed ligand. For example, the ligand MeeTREN binds copper strongly, meaning that its usage is compatible with a broad array of buffers, whereas PMDETA binds copper comparatively weaker, meaning that it may be less suited for use in combination with certain buffers which themselves coordinate copper.

[0199] The reaction composition was prepared as described in Example 3, except with the addition of glycine (2807 mg, 99.5% grade, from Chemsolute) and NaOH (750 mg, from Th. Geyer GmbH & Co. KG) to container A prior to sonication. The amounts specified herein, total of 1000 mL, may be scaled to accommodate the preparation of smaller or larger volumes of reaction compositions.

[0200] The use of a buffer with the solvent allow s for further controlling the pH level of a reaction composition. Buffer systems which stabilize the pH level in two or more pH regions (has 2 or more pBGH values) allow for a rapid alternation between said pH regions in the case where a suitable amount of acid and / or base is added.

[0201] Example 5

[0202] Method for assessment of surface polvmer brush) forming ability (rate study) of a reaction

[0203] This example illustrates a procedure for assessing the rate with which polymer brushes are formed over time in the reaction composition of Example 3. This procedure serves as a reference in subsequent examples. 7 silicon wafer substrates (same grade as described in Example 1) were pre-cleaned as described in Example 1, and polymerization initiators were attached on the surface as described in Example 2. Reaction compositions were prepared as described in Example 3. The substrates were then immersed simultaneously in the reaction composition, and individually recovered from the reaction composition according to the following procedure. At minute 0, defined as 5 minutes after addition of (a solution of) catalyst activator (NaAsc). all substrates were immersed into the reaction composition. At subsequent timestamps, at minutes 2, 5, 7.5, 10, 20, 30, and 40, one substrate was recovered at each instance from the reaction composition. In this way, 7 substrates subjected to the same reaction composition but for different durations of time (residence time) are obtained, allowing for the assessment of the surface polymer growth as a function of time.

[0204] The pH of the reaction composition w as measured using a pH meter (Metrohm 913 pH meter or Metrohm 914 pH / DO / Conductometer).

[0205] After surface polymer formation, the substrates were cleaned by sonication in Dl-water (grade as Example 1) for 5 minutes, followed by sonication (with specification as described in Example 1) for 5 minutes. The substrates were allow ed to dry in ambient air at ambient pressure.

[0206] After cleaning and div ing the surface polymerized substrates, the dry film thicknesses of the formed (collapsed) surface polymers were analyzed using ellipsometry (J. A. Woollam M-2000 Ellipsometer). For each substrate, the dry film thicknesses (in nm) of the surface polymers were plotted against time (in minutes) at which the substrate was recovered. In this way, the rate of surface polymer formation w as evaluated as a function of time. From here, the “rate” of a given reaction composition is referred to as the thickness (in nm) of surface polymers which were obtained as a function of time.

[0207] Example 6

[0208] Method for the surface brush) forming ability (lifetime) of a reaction

[0209] This example illustrates a procedure for assessing the surface polymer forming abil i t over time of a reaction composition. This procedure serves as a reference in subsequent examples. Silicon wafer substrates (12, same grade as described in Example 1) were pre-cleaned as described in Example 1, and polymerization initiators were attached to the surface as described in Example 2. Reaction compositions were prepared as described in Example 4. The substrates were then immersed in the reaction composition, each at a time in a continuous manner according to the following procedure. At minute 0, defined as the point of monomer addition and 5 minutes after addition of (a solution of) catalyst activator (NaAsc), the first substrate was immersed into the reaction composition for 10 minutes. At minute 10, the first substrate was removed, and another substrate was immersed in the liquid for 10 minutes. This was repeated until a total number of 12 substrates were subjected to surface polymer (polymer brush) formation for 10 minutes each, over the course of 120 minutes, in a sequential / consecutive manner.

[0210] The pH of the reaction composition was measured using a pH meter (Metrohm 913 pH meter or Metrohm 914 pH / DO / Conductometer). In some cases, the concentration of dissolved oxygen in the reaction composition was monitored using an Ch-selective sensor (Pyroscience FireSting- GO2). The read-out partial pressure may be converted into a dissolved oxygen content given in molarity utilizing Henry’s Law as described above.

[0211] After surface polymer formation, the substrates were cleaned by sonication in Dl-water (grade as Example 1) for 5 minutes, followed by sonication (with specification as described in Example 1) for 5 minutes. The substrates were allowed to dry in ambient air at ambient pressure.

[0212] After cleaning and drying the surface polymerized substrates, the dry film thicknesses of the formed (collapsed) polymer brushes were analyzed using ellipsometry (J.A. Woollam M-2000 Ellipsometer). For each substrate, the dry film thicknesses (in nm) of the surface polymers were plotted against time (in minutes) at which the 10 minutes of polymerization concluded. In this way, the surface polymer forming ability of the bath containing the reaction composition were evaluated in 10-minute interv als throughout the 120 minutes of the lifetime study.

[0213] Example 7

[0214] UV / Vis spectroscopic analysis to determine correlation between catalvst activity and pH intervals In this example, the pH range in which the Cu / MeeTREN complex may catalyze surface polymer formation is examined via UV / Vis spectroscopic analyses. The Cu / MeeTREN complex (with Cu in its Cu(II) oxidation state (inactive for surface polymer formation), specifically) displays a distinct absorption spectrum which is distinguishable from scenarios where Cu exists without com- plexation to MeeTREN, obtained in cases where a low pH causes decomposition of the Cu / MeeTREN complex.

[0215] UV / Vis spectroscopic analysis (LLG-uni<S7’EC 2 Spectrophotometer) was performed for a Cu / MeeTREN solution prepared as described in Example 3, established to be of a native pH of 11.8. The hereby obtained UV / Vis spectrum was compared to UV / Vis spectra of the same Cu / MeeTREN solution at lower pH levels, facilitated by small incremental additions of H2SO4 (commercially available, 95-97% grade from Chemsolute), with continuous pH measurements. With this method, UV / Vis spectra of the Cu / MeeTREN solution were obtained in the range of pH 11.8 to 2.2. These UV / Vis spectra, as well as a reference spectrum of Cu(II)Ch in Dl-water (with no ligand) are shown in Fig. 12. For the Cu / MeeTREN complex solution at native pH, two absorption maxima were found at max 1 = 700 nm and km ax 2 = 870 nm, respectively, ascribed to the characteristic absorption profde of a Cu / MeeTREN complex. As the solution was acidified to pH 9.0. minimal change in the UV / Vis spectrum was seen. Following further gradual acidification to pH 5.0, the peak at / .max i diminished while the peak at Amax2 increased. The pH at which this change was most rapid (pH 8.4) coincides with the pKaHi of the Cu / MeeTREN complex (Fig. 13). At pH < 5.0, the UV / Vis spectrum of the Cu / MeeTREN solution undergoes further changes reducing both peaks at / .max I and / .max2. At pH < 3.0, the UV / Vis spectrum of the Cu / MeeTREN solution coincided with that of non-ligated Cu(Il)C12 in Dl-water, meaning that full decomposition of the Cu / MeeTREN complex had occurred. The second transition is interpreted as the second protonation of the Cu / MeeTREN complex leading to decomposition of Cu / MeeTREN complex. This occurs around pH 4.1, herein translated to a pICTb value of 4. 1. These observations indicate the pH intervals in which the Cu / MeeTREN catalyst complex exists as a stable species and, hence, may catalyze surface polymer formation: At pH > 8.4, high catalytic effect and polymerization rate is expected; at 8.4 > pH > 4.1, catalytic effect and stable, controlled polymerization rate is expected; at pH < 4.1 low' or no catalytic effect is expected. Thus, quenching of surface polymerization is expected to take place below the pICTb value.

[0216] Other copper / ligand complexes (different from MeeTREN) may be analyzed in a similar manner, indicating the pH intervals with complexation between the ligand and the catalyst in order to determine the pH at which surface polymer formation quenching occurs. Similarly, pH range studies for the Cu / PMDETA catalyst complex were determined by the UV / Vis spectroscopy method described for Cu / MesTREN. The results are shown in Figs. 14 (UV / Vis) and 15 (absorption as function of pH); at pH > 8.6, high catalytic effect and polymer formation rate is expected; at 8.6 > pH > 3.4, controlled catalytic effect and surface polymer formation rate is expected; at pH < 3.4, low or no catalytic effect is expected.

[0217] Similarly, pH range studies for the Cu / TPMA catalyst complex is shown in Figs. 16 (UV / Vis) and 17 (absorption as function of pH); at pH > 7.4, high catalytic effect and surface polymer formation rate is expected; at 7.4 > pH > -0.4, stable and controlled catalytic effect and surface polymer formation rate is expected; at pH < -0.4, low or no catalytic effect is expected.

[0218] Using UV / Vis spectroscopic analysis in the described fashion allows for rapid determination of the pH ranges wherein a given catalyst / ligand complex exists as a stable species, as well as pH ranges where the catalyst / ligand complex does not exist as a stable species. This knowledge may then be utilized set the pH conditions of a reaction composition for quenching and re-initiation of the surface polymer formation, and, thus, modulate pH of the reaction composition at a suitable time to traverse the boundary between two pH values. In one iteration, the pH of a reaction composition may be decreased from a pH range where the catalyst / ligand complex exists as a stable species, to a pH range where the complex does not exist as a stable species; as a result, the polymer-forming ability of the reaction composition may be quenched due to catalyst / ligand complex decomposition, in the sense that the polymer-forming ability is markedly reduced. Such a manipulation may be highly beneficial, for example to stop a polymer-forming process at a specific point in time where the target surface polymer thickness has been achieved.

[0219] Example 8

[0220] UV / Vis spectroscopical demonstration of Cu / ligand complex decomposition and reassembly facilitated by acid or base addition.

[0221] In this example, the decomposition of a copper / ligand complex followed by reassembly of the copper / hgand complex is shown via UV / Vis spectroscopic analyses by addition of either an acidic (decomposition) or alkaline substance (reassembly), respectively.

[0222] A catalyst / ligand complex solution (Cu / MeeTREN) as described in Example 4, established to be of a native pH of 9.3. was subjected to UV / Vis spectroscopic analysis (LLG-uni>S77iC 2 Spectrophotometer). The pH was adjusted to pH 2.35 by the addition of HC1 (37% aq.) as acidic substance, and a second UV / Vis spectrum was recorded. The pH was readjusted to pH 9.3 (corresponding to the pH before acid addition) by the addition of NaOH (10 M aq.) as alkaline substance, and a third UV / Vis spectrum was recorded.

[0223] The obtained UV / Vis spectra (Fig. 18) show the initial existence of the Cu / MeeTREN complex at pH 9.3, followed by significant decomposition (lack of a characteristic catalyst / ligand complex absorption profile) when pH was adjusted to pH 2.35 by addition of an acidic substance, and the reassembly of the Cu / MeeTREN complex (recovery of a characteristic catalyst / ligand complex absorption profile) when pH was readjusted to pH 9.3 by addition of an alkaline substance. It was hereby shown that the decomposition of Cu / MeeTREN complex upon pH lowering may be reversed quantitatively by subsequent base addition to obtain what appears to be full reassembly, thus, reversible quenching was obtained. As a result, the surface polymer-forming ability7of a reaction composition comprising Cu / MeeTREN complex may be re-initiated from a state of being quenched by lowering the pH below the pKafk value of the Cu / MeeTREN complex. In combination with the ability to quench the polymer-forming ability of a reaction composition (as described in Example 7), the abi 1 i ty to reactivate (re-initiate) a quenched reaction composition may be highly beneficial to the reusability, utility, and overall economic viability of a setup, depending on application-specific demands.

[0224] Example 9 of surface poly mer formation - analy sis

[0225] This example demonstrates the utility and efficiency of quenching an ongoing surface polymer formation through acidification of the reaction composition. Utilizing the knowledge obtained from UV / Vis spectroscopical studies (decomposition of a catalyst / ligand complex by acidification as described in Example 7), the addition of an acidic substance to lower pH below the pKaH2 value of the catalyst / ligand complex during an ongoing polymerization was investigated. At a pH value under a certain threshold (pKaH2 of the catalyst / ligand complex), minimal further surface polymer formation occurs. At the same time, the surface polymer already formed at the point of quenching remains stable (is not degraded by acidification). Silicon wafer substrates (7 substrates, same grade as described in Example 1) were pre-cleaned as described in Example 1, and polymerization initiators were attached to the surface as described in Example 2.

[0226] To a glass container (container A) was added N,N,N',N'',N"-pentamethyldiethylene-triamine (PMDETA, 60.0 pL. >99% grade from Sigma-Aldrich), Dl-water (15.94 mL, grade specified in Example 1) and CuCh 2(H2O) (13.6 mg, > 99.5% grade, from Sigma-Aldrich). To this solution was added a solvent system consisting of Dl-water (374 mL) and Ao-propanol (537 mL, 96% grade from KiiltoClean). Container A was sonicated for 1 minute to reduce air pockets in solution. In a separate glass container (container B), sodium ascorbate (4.00 g, >98% grade from Sigma- Aldrich) was dissolved in Dl-water (15 mL). The content of container B was mixed into container A. After 5 minutes, a monomer consisting of tert-butyl methacrylate (tBMA, 75 mL, >98% grade, stabilized with MEHQ, from TCI Chemicals) was added to container A. The liquid was ready to use for surface polymer formation.

[0227] Substrates were subjected to the reaction composition as described in Example 5. One substrate was recovered at minutes 2, 5, 7.5, 10, 20, 30, and 40, respectively. After recovery of the 7thsubstrate at minute 40, the substrates were cleaned by sonication in Dl-water (grade as Example 1) for 5 minutes, followed by sonication (with specification as described in Example 1) for 5 minutes. The substrates were allowed to dry in ambient air at ambient pressure.

[0228] Three additional rate experiments were conducted in parallel in a similar manner in individual reaction compositions prepared as described for the initial rate experiment, in three different containers, except with acidification by addition of methanesulfonic acid (MSA, 3000 pL, > 99% grade from Sigma- Aldrich) before recovery of the 1stsubstrate (minute 10, first container), the 2ndsubstrate (minute 20, second container), or the 3rdsubstrate (minute 30, third container), respectively. Acidification resulted in a rapid lowering of pH, from the intrinsic pH of 8.2 of the reaction composition to a pH of 1.8, a value being below the pFLTb of the Cu / PMDETA complex (cf. Example 7). The thicknesses of the surface polymers (polymer brushes) were obtained for each substrate by average dry film ellipsometry. Results are reported in Table 3 and visualized in Fig. 19. It was observed that in all 3 experiments, the time-dependent increase of the surface polymer thickness after acidification (quenching) was markedly lowered from the time of acidification towards the end of the surface polymer formation experiment. This demonstrated that adding an acidic substance effectively caused decomposition of the Cu / PMDETA complex, thus, quenching the surface polymer formation.

[0229] The inventors believe the slope (a in y=ax+b) in Fig. 19 to be defining of the extent of quenching, i.e. the percentage reduction in surface polymer formation upon quenching by addition of acidic substance, measured as the decrease in polymer brush grow th over time. Thus,

[0230] (1) Extent of quenching

[0231] For plots of changes in the linear correlation between polymer brush thickness and time upon quenching the reaction, see Fig. 20A-D (for reference plot without quenching, quenching after 10 minutes, quenching after 20 minutes, and quenching after 30 minutes, respectively). In each case, a clear decline in the slope mentioned above is apparent at the time point for acid addition.

[0232] Table 3. Comparison of surface polymer (polymer brush) formation rates before and after quenching.

[0233] From these data, it can be concluded that the extent of quenching was at least 94%. Thus, a surface polymer formation can effectively be quenched by addition of an acidic substance to lower the pH of the reaction composition below the pKaH2 of the catalyst complex (here Cu / PMDETA). Furthermore, the results indicate that a given thickness of formed surface polymer on a substrate can be obtained by quenching the surface polymer formation at an appropriate point in time during surface polymer formation. Thus, quenching may be a valuable strategy in surface polymer formations.

[0234] Example 10

[0235] Re-initiation of a reaction composition for surface polymer formation by addition of an alkaline substance

[0236] In this example, the addition of an alkaline substance for raising the pH above the pKaH2 of a catalyst / ligand complex to re-initiate surface polymer formation was investigated. Using the findings from UV / Vis spectroscopical analyses (reassembly of a catalyst / ligand complex by basification as described in Example 8), the addition of an acidic substance to lower pH of the reaction composition below the pKaH2 value of the catalyst / ligand complex (quenching), followed by the addition of an alkaline substance to raise the pH of the reaction composition above the pKaH2 value of the catalyst / ligand complex is investigated.

[0237] Silicon wafer substrates (12, same grade as described in Example 1) were pre-cleaned as described in Example 1, and polymerization initiators were attached to the surface as described in Example 2. The reaction composition was prepared as described in Example 4, with the addition of a magnetic stirring bar to the container holding the reaction composition. The intrinsic pH of the reaction composition was measured to 9.6. The substrates were then immersed in the reaction composition, each at a time in a sequential manner according to the following procedure. At minute 0, defined as the point of monomer addition and 5 minutes after addition of (a solution of) catalyst activator (NaAsc), the 1stsubstrate was immersed in the reaction composition for 10 minutes. At minute 10, the 1stsubstrate was removed, and the 2ndsubstrate was immersed in the reaction composition for 10 minutes. At minute 20 before extraction of the 2ndsubstrate, the reaction composition was stirred at 300 RPM while MSA (4.8 mL, > 99% grade from Sigma- Aldrich) was added, resulting in acidification of the reaction composition. The substrate was then extracted from the reaction composition. Upon stabilization of pH at 2.4 (assessed by continuous measurements by a pH meter), the stirring was stopped, and the 3rdsubstrate was immersed in the reaction composition for 10 minutes. At minute 30, the 3rdsubstrate was removed, and the 4lhsubstrate was immersed in the reaction composition for 10 minutes. At minute 40, the 4thsubstrate was removed, and the reaction composition was stirred at 300 RPM while NaOH (8 mL, 10 M in Dl-water) w as added, resulting in the basification of the reaction composition. Upon stabilization of pH at 9.6 (assessed by continuous measurements by a pH meter), the stirring was stopped, and the 5thto 10th substrate were immersed in the reaction composition, each at a time for 10 minutes, between minutes 50-120. Then, the 12 substrates were cleaned, and analyzed as described in Example 6. Surface polymer thicknesses and pH values recorded for individual substrates are shown in Table 4; ellipsometric data and pH are plotted in Fig. 21, in addition to O2 measurements (Pyroscience FireSting-GO2) which show an increase in the concentration of dissolved molecular oxygen in the time interval where pH is below the pKa value of ascorbic acid.

[0238] Table 4. Comparison of surface polymer formation rates before and after addition of quenching agent and reactivation agent.

[0239] The results shown in Table 4 clearly demonstrate the high utility of the reversible quenching (quenching followed by re-initiation). Upon quenching the reaction composition by acidification at a given point in time (in this instance, after 20 minutes), the pH is lowered below the pKaH of the Cu / Me6TREN complex, and the surface polymer formation does not proceed. Then, upon subsequently reactivating (re-initiating) the surface polymer forming ability of the reaction composition, the pH level may be brought back to the initial value before acidification, and the surface polymer forming ability of the reaction composition is restored for surface polymer formations on additional substrates. Obtained surface polymer thicknesses on substrates which are surface polymerized before quenching are highly similar to surface polymer thicknesses on substrates which are polymerized after reactivation (re-initiation of polymerization reaction). Thus, selectively quenching and selectively re-initiating a surface polymerization reaction may be highly valuable in various applications, and it appears possible to provide an “on / off’ cycle of surface polymer formation.

[0240] Example 11

[0241] Multiple cycles of quenching and reactivation of a reaction composition

[0242] This example demonstrates the ability of a reaction composition to undergo quenching and reinitiation for surface polymer formation multiple times without compromising the surface polymer-forming ability when the pH is above the pK H? value of the catalyst / ligand complex. Tn this example, Cu / MesTREN was used.

[0243] Silicon wafer substrates (12 in total, same grade as described in Example 1) were pre-cleaned as described in Example 1, and polymerization initiators were attached to the surface as described in Example 2. The reaction composition was prepared as described in Example 4, and a reaction composition lifetime study was performed as described in Example 4, with the addition of a magnetic stirring bar to the container holding the reaction composition. The intrinsic pH of the reaction composition was measured to 9.6. The substrates were then immersed in the reaction composition, each at a time in a sequential manner according to the following procedure. At minute 0, defined as the point of monomer addition and 5 minutes after addition of (a solution of) catalyst activator (NaAsc), the 1stsubstrate was immersed in the reaction composition for 10 minutes. At minute 10, the 1stsubstrate was removed, and the 2ndsubstrate was immersed in the reaction composition for 10 minutes. At minute 20 before extraction of the 2ndsubstrate, the reaction composition was stirred at 300 RPM while MSA (4.8 mL, > 99% grade from Sigma- Aldrich) was added, resulting in acidification of the reaction composition. The 2ndsubstrate was then extracted from the reaction composition. Upon stabilization of pH at 2.4 (assessed by continuous measurements by a pH meter), the stirring was stopped, and the 3rdsubstrate was immersed in the reaction composition for 10 minutes. At minute 30, the 3rdsubstrate was removed, and the 4thsubstrate was immersed in the reaction composition for 10 minutes. At minute 40, the 4thsubstrate was removed, and the reaction composition was stirred at 300 RPM while NaOH (8 mL, 10 M in Dl-water) was added, resulting in the basification of the reaction composition. Upon stabilization of pH at 9.6 (assessed by continuous measurements by a pH meter), the stirring was stopped, and the 5thsubstrate was immersed in the reaction composition for 10 minutes. At minute 50, the 5thsubstrate was removed, and the 6thsubstrate was immersed in the reaction composition for 10 minutes. At minute 60 before extraction of the 6thsubstrate, the reaction composition was stirred at 300 RPM while MSA (4.8 mL, > 99% grade from Sigma- Aldrich) was added, resulting in acidification of the reaction composition. The substrate was then extracted from the reaction composition. Upon stabilization of pH at 2.4 (assessed by continuous measurements by a pH meter), the stirring was stopped, and the 7thsubstrate was immersed in the reaction composition for 10 minutes. At minute 70, the 7thsubstrate was removed, and the 8thsubstrate was immersed in the reaction composition for 10 minutes. At minute 80, the 8thsubstrate was removed, and the reaction composition was stirred at 300 RPM while NaOH (8 mL, 10 M in Dl-water) was added, resulting in the basification of the reaction composition. Upon stabilization of pH at 9.6 (assessed by continuous measurements by a pH meter), the stirring was stopped, and the 9thto 12thsubstrate were immersed in the reaction composition, each at a time for 10 minutes, between minutes 90- 120. Upon completion of the experiment, the 12 substrates were cleaned, and analyzed as described in Example 6. Surface polymer thicknesses and pH values recorded for individual substrates are show n in Table 5; ellipsometric data and pH are plotted in Fig. 22, in addition to O2 measurements (Pyroscience FireSting-GO2) which show an increase in the concentration of dissolved molecular oxygen in the time interval where pH is below the pKa value of ascorbic acid.

[0244] Table 5. Comparison of PB formation rates before and after addition of 1staddition of acidic substance, 1staddition of alkaline substance, 2ndaddition of acidic substance, and 2ndaddition of alkaline substance. The results shown in Table 5 demonstrate the ability of the reaction composition to undergo multiple quenching / reactivation (re-initiation) cycles while maintaining high uniformity and predictability in terms of the thickness of surface polymer formed in 10 minute-intervals both before the first and second quenching, and after the first and second re-initiation. Substrates inserted in the reaction composition, when the reaction composition was quenched, show minimal formation of surface polymers. It is thereby shown that the quenching by acidification is highly reversible upon basification, and that the surface polymer-forming ability of the reaction composition after the first or second reactivation is not changed significantly when compared to its initial performance before the first quenching event. The inventors believe that the current method may be employed for more quenching / reactivation cycles than 2, e.g., 3, 4, or 5 cycles, with a similar low deviance in the thickness of formed surface polymers. The number of quenching / reactivation cycles employed as desired, and the polymerization time (here exemplified by 10 minutes) may be tailored to suit a specific application as desired.

[0245] Example 12

[0246] Substances for quenching and re-initiating surface polymer formation

[0247] This example demonstrates the application of acid H2SO4 and base LiOH to quench and re-initiate, respectively, a surface polymer formation.

[0248] Silicon wafer substrates (6 in total, same grade as described in Example 1) were pre-cleaned as described in Example 1, and polymerization initiators were attached to the surface as described in Example 2. The reaction composition was prepared as described in Example 4, with the addition of a magnetic stirring bar to the container in which the surface polymer formation took place. The intrinsic pH of this solution was measured to 9.6. The substrates were then immersed in the reaction composition, each at a time in a sequential manner according to the following procedure. At minute 0, defined as the point of monomer addition and 5 minutes after addition of (a solution of) catalyst activator (NaAsc), the 1stsubstrate was immersed in the reaction composition for 10 minutes. At minute 10, the 1stsubstrate was removed, and the 2ndsubstrate was immersed in the reaction composition for 10 minutes. At minute 20 before extraction of the 2ndsubstrate, the reaction composition was stirred at 300 RPM while H2SO4 (2.0 mL, 95-97% grade from Chemsolute) was added, resulting in acidification of the reaction composition. The substrate was then extracted from the reaction composition. Upon stabilization of pH at 2.4 (assessed by continuous measurements by a pH meter), the stirring was stopped, and the 3rdsubstrate was immersed in the reaction composition for 10 minutes. At minute 30, the 3rdsubstrate was removed, and the 4thsubstrate was immersed in the reaction composition for 10 minutes. At minute 40, the 4thsubstrate was removed, and the reaction composition was stirred at 300 RPM while LiOH (30 mL, 3.33 M in Dl-water) was added, resulting in the basification of the reaction composition. Upon stabilization of pH at 9.1 (assessed by continuous measurements by a pH meter), the stirring was stopped, and the 5thand 6thsubstrate were immersed in the reaction composition, each at a time for 10 minutes, until minute 60. Then, the 6 substrates were cleaned, and analyzed as described in Example 6. Surface polymer thicknesses and pH values recorded for individual substrates are shown in Table 6; ellipsometric data and pH are plotted in Fig. 23, in addition to O2 measurements (Pyroscience FireSting-GO2) which show an increase in the concentration of dissolved molecular oxygen in the time interval where pH is below the pKa value of ascorbic acid. Table 6. Comparison of surface polymer formation rates before and after addition of acidic substance and alkaline substance.

[0249] The results shown in Table 6 demonstrate the successful quenching and re-initiation of a reaction composition for surface polymer formation, and it is inferred that the traits of such acidic and alkaline substances responsible for such quenching and re-initiation are their ability to modulate the pH via increasing or decreasing the amount of free protons in solution, thus, causing decomposition and reassembly of the Cu / MeeTREN complex, and not merely an effect caused by their counterions (such as sulfonates or alkali metal cations). The authors believe that abroad range of common, commercially available pH-modulating substances may be utilized in a similarly successful manner; for example, acids such as HCL H3PO4, 2.2.2-trifluoroacetic acid, p- toluenesulfonic acid, and / or nitric acid, and bases such as potassium hydroxide, tripotassium phosphate, sodium carbonate, and / or sodium ethoxide may successfully be used for quenching and re-initiation, respectively. The ability to choose between different acids and bases for quenching and reactivating the surface polymer- forming ability of a reaction composition is a clear advantage, as some applications may involve substrates, containers, or surface polymers which are sensitive toward certain substances but tolerant toward others.

[0250] Example 13

[0251] Quenching and re-initiating a reaction composition

[0252] This example demonstrates the quenching and reactivation (re-initiation) of a reaction composition. Silicon wafer substrates (8 substrates, same grade as described in Example 1) were pre-cleaned as described in Example 1, and polymerization initiators were attached to the surface as described in Example 2. The reaction composition was prepared by adding to container A 16 ml of copper / ligand complex solution comprised of A,A,A',JV",A"-pentamethyldiethylenetriamine (PMDETA, 60.0 pL. >99% grade from Sigma- Aldrich), Dl-water (15.940 mL, grade specified in Example 1) and CuC12-2(H2O) (13.6 mg, > 99.5% grade, from Sigma-Aldrich)). To this solution was added a solvent system with a buffer comprising Dl-water (374 mL), iPrOH (537 mL, >99.8% grade from Chemsolute), A-cyclohexyl-2-aminoethanesulfonic acid (CHES, 7753 mg, >99% grade from Sigma- Aldrich) and NaOH (610 mg). Container A was sonicated for 1 minute to reduce air pockets in solution. In a separate glass container (container B), sodium ascorbate (4.00 g. >98% grade from Sigma- Aldrich) was dissolved in Dl-water (15 mL). The content of container B was mixed into container A. After 3 minutes, tert-butyl methacrylate monomer ( / BMA. 75 mL, >98% grade, stabilized with MEHQ, from TCI Chemicals) was added to container A. The pH of this solution was measured to 9.3. The Cu / PMDETA complex was activated by sodium ascorbate and ready for surface polymer formation.

[0253] A quenching and re-initiation experiment was performed as described in Example 10, including quenching by addition of MSA (4.56 mL) at minute 20, and reactivation by addition of NaOH (10 M aq., 8.50 mL) at minute 40. although in this case the experiment concluded after 80 minutes. Surface polymer thicknesses and pH values recorded for individual substrates are shown in Table 7; ellipsometric data and pH are plotted in Fig. 24.

[0254] Table 7. Comparison of surface polymer formation rates before and after addition of acid / quenching agent and base / reinitiation agent.

[0255] The results shown in Table 7 further confirm the ability to quench and re-initiate a reaction composition for surface polymer formation. In this experiment, the monomer is / BMA. and the choice of monomer determines the surface polymer (polymer brush) which is formed. Modulating the reaction composition in terms of employed catalyst / ligand complex (in this case, Cu / PMDETA) is likewise highly desirable, as different catalyst ligand complexes may lead to polymerization rates as well as maximal surface polymer thicknesses different from other catalyst / ligand complexes. The ability to perform quenching and re-initiation in various solvents, with various monomers and catalyst / ligand complexes, e.g., due to solubility of components of the reaction composition and surface polymer wetting. It may further be an advantage to include a buffer in the reaction composition to support stability of the reaction composition following acidification or basification as some applications may prescribe certain pH values in terms of surface polymer or substrate stability.

[0256] Example 14

[0257] Stability and preservation of chain-end functionality of surface polymers upon quenching by acidification - formation of block copolymers

[0258] This example demonstrates the quenching of a surface polymer formation by acidification and subsequently subjected to further surface polymer formation initiated from preserved end functionalities of the first layer of surface polymers (end functionality comprises a polymerization initiator), i.e., formation of a block copolymer. In this experiment, the acid-quenched substrate is subjected to further surface polymer formation with an additional polymer layer by submerging the acid-quenched substrate in a second activated reaction composition, thereby forming a block copolymer on the surface of the substrate (grown from the firstly formed surface polymer layer).

[0259] A silicon wafer substrate (same grade as described in Example 1) was pre-cleaned as described in Example 1, and polymerization initiator was attached to the surface as described in Example 2.

[0260] The substrate was subjected to a first reaction composition containing the monomer tBMA, prepared as described in Example 9. The substrate was subjected to the first reaction composition for a total of 40 minutes, with the addition of methanesulfonic acid (MSA, 3000 pL, > 99% grade from Sigma-Aldrich) after 30 minutes, quenching the first reaction composition and producing a first surface polymer layer of PtBMA on the substrate. The substrate was then cleaned as described in Example 9.

[0261] This substrate was subsequently subjected to a second reaction composition containing the monomer MMA, prepared as described in Example 3, for 10 minutes before cleaning as described in Example 9, producing a second surface polymer layer of PMMA on top of the first surface polymer layer of PtBMA, i.e. a block copolymer.

[0262] The dry film thicknesses of the formed (collapsed) surface polymer (polymer brushes) after the first and second surface polymer formations, respectively, were obtained by ellipsometry' (Fig. 25). Results are summarized in Table 8.

[0263] Table 8. Comparison of surface polymer thicknesses of a 1stsurface polymer after quenching, and a block copolymer obtained from a subsequent polymerization.

[0264] By comparing the surface polymer thicknesses after the 1stsurface polymer formation (<20 nm of PtBMA) and the 2ndsurface polymer formation (>80 nm of Woc£-co-PtBMA-PMMA), it is seen that both polymerization events were able to form of surface polymers on the substrate. As the 2ndpolymerization event was conducted with no further supplements of moieties acting as polymerization initiators, this demonstrates that the propagating polymer chain ends survived the 1stpolymer formation reaction as well as the steps in-between the polymer formation reactions (quenching and cleaning). Accordingly, this indicates that the chain-end functionality responsible for further propagation is retained upon quenching of the surface polymer formation by acidification. Acidification is therefore a non-destructive tool for minimizing the surface polymer formation which allows for further formation of surface polymers, either by reactivating the quenched reaction composition (as demonstrated in Examples 10 and 1 1), or by subjecting the substrate to another activated reaction composition (as demonstrated in this example). The quenching strategy described herein is thus applicable also for the formation of block copolymers which expands the surface polymer characteristics obtainable.

[0265] Example 15

[0266] Quenching the formation of surface polymers on silicon nanoparticle material as substrate

[0267] This example shows the applicability of the herein disclosed quenching by acidification of the surface polymer formation on silicon nanoparticle material.

[0268] Silicon nanoparticles (SiNP) were first treated with HF to form a H-terminated Si-surface, followed by the grafting of a polymerization inhibitor 4-vinylbenzene chloride (VBC) decorated with a polymerization initiator in the following manner: In a polypropylene conical flask equipped with a magnetic stirbar, 20 g SiNP material (20 g. >97% grade with < 1 % oxygen content, D50 = 100 nm from MTI corporation) was suspended in methanol (920 mL, >99.85% grade from ChemSolute) by stirring it for 10 minutes and sonicating in a bath sonicator for 10 minutes. The suspension was returned to a stirplate and 80 mL HF (48%, aq.) was added to the flask. The contents of the flask were then stirred for 10 minutes (500 RPM), sonicated in a bath sonicator for 10 minutes, and stirred for 10 minutes (500 RPM). The suspension containing the SiNP material was divided evenly between two centrifuge bottles and recovered by centrifugation (5 minutes at 3900 RPM, Eppendorf 5810 centrifuge). The supernatant was discarded, and the obtained Si nanoparticle material recovered. The recovered nanoparticle material was suspended in 0.5 % HF in methanol (10 mL 48% HF (aq.) in 990 mL MeOH, >99.85% grade from ChemSolute) by sonication in a bath sonicator (5 minutes), shaken on an orbital shaker table (MaxQ 2000, Thermo Scientific) (5 minutes) and sonicated in a bath sonicator (10 minutes). The suspended SiNP material was then recovered by centrifugation (5 minutes at 3900 RPM), by discarding the supernatant. Finally, the nanoparticle material was suspended in argon-purged toluene (900 mL) by sonication in a bath sonicator (5 minutes), shaken on an orbital shaker table (5 minutes), and sonicated in a bath sonicator (10 minutes).

[0269] To surface-graft 4-VBC, the HF-treated SiNP material suspended in toluene was parted evenly between 4 glass bottles with screw cap lids (250 mL, Labsolute) which were equipped with magnetic stirbars and placed on magnetic stirplates and stirred at 300 RPM. The Bluecap bottles were closed with septa while keeping an argon flow in the bottles. VBC (142.5 mL, 90% grade from Sigma- Aldrich) was passed through AI2O3 columns, and then distributed evenly to the 4 glass bottles. Then, 4-decylbenzyl diazonium tetrafluoroborate (1.6 g (which was pre-synthesized by suspending 4-decylaniline (9.54 g. 97% grade from Sigma-Aldrich) in glacial acetic acid (42 mL, >99.5% grade from ChemSolute) and propionic acid (42 mL, >99.5% grade from Sigma-Aldrich), adding HBF4 (48% aq. , 49 mL, from ThermoFisher Scientific), cooling to 3° C in an ice bath, carefully adding NaNCh (4.13 g, >97% grade from Sigma- Aldrich), stirring for 2 h, adding DI- water (45 mL) at 10 °C, resulting in a solid which was filtered, washed 4 times with DI- water, and dried in vacuo), was distributed evenly in the 4 bottles.

[0270] After 2 hours the suspended SiNP material was transferred to centrifuge bottles and recovered by centrifugation (5 minutes at 3900 RPM). The supernatants were discarded, and the crude VBC- functionalized SiNP material was subjected to 2 cycles of the following workup: the SiNP material was resuspended by adding di chloromethane (DCM, 50 mL, >99.9% grade from ChemSolute) to each centrifuge bottle and the bottles were sonicated for 10 minutes in a bath sonicator and shaken on an orbital shakerboard until the SiNP material was well resuspended. Then, methanol (250 mL, >99.85% grade from ChemSolute) was added to each of the centrifuge bottles, which were then centrifuged (5 minutes at 3900 RPM). The supernatant was discarded.

[0271] The SiNP material was then dried and ground by mortar and pestle to obtain the purified VBC- functionalized SiNP material as a fine powder for usage in the subsequent surface polymer formation.

[0272] In each of 4 glass containers Al. A2. A3, and A4 containing a magnetic stirring bar, the following reaction compositions were prepared: VBC-functionalized SiNP material (2.5 g) and iPrOH (175 mL, >99.8% grade from Chemsolute) were added, and a good suspension was obtained by sonicating for 10 minutes followed by stirring at 300 RPM for 10 minutes. Dl-water (48.75 mL), 7.8 mL copper / ligand complex solution consisting of tris [2-(dimethylamino)ethyl] amine (MesTREN, 37 pL, >98% grade from abcr or Alfa Aesar), Dl-water (7.763 mL), and Cu(II) (324 mg / L, obtained from a solid copper source, however, solid copper not being present in the catalyst / ligand complex solution), and tBMA (18.75 mL, >98% grade, stabilized with MEHQ, from TCI Chemicals) were added. In this way, 4 identical reaction compositions were obtained.

[0273] In each of 4 glass containers Bl, B2, B3, and B4, NaAsc (1.00 g, >98% grade from Sigma- Aldrich) were dissolved in Dl-water (3.75 mL) to produce 4 identical activator solutions (activator for the Cu / MeeTREN complex).

[0274] To each of the compositions Al, A2, A3, and A4 were added one of the activator solutions Bl, B2, B3, and B4 at the same time (defined as minute 0), leading to the initiation of surface polymer formation on the VBC-functionalized SiNP material. Each composition was subjected to 10 minutes of sonication, 10 minutes of stirring at 300 RPM, 10 minutes of sonication, and 10 minutes of stirring at 300 RPM, totaling a duration for 40 minutes.

[0275] To each of the 4 reaction compositions were added MSA (0.75 mL, (>99% grade from Sigma- Aldrich) at different points in time to reach pH 1.8; at minutes 2, 5. 10. and 40, respectively. The pH of 1.8 is below the pKaH2 of the Cu / MEeTREN complex, causing decomposition of the complex. In analogy to Example 9, the polymerization occurring in each reaction vessel was expected to be quenched upon MSA addition, such that polymerization would occur to 4 different extents (and, thus, different surface polymer thicknesses).

[0276] Immediately after MSA addition to the 4threaction composition at minute 40, each product was worked up by pouring them into individual centrifuge bottles and centrifuging them for 5 minutes at 3900 RPM, the supernatants were discarded, and the crude surface polymer-functionalized SiNP material was subjected to 2 cycles of the following workup: the SiNP material was resuspended by adding DCM (20 mL, >99.9% grade from ChemSolute) to each centrifuge bottle and the bottles were sonicated for 5 minutes in a bath sonicator. Then, methanol (200 mL, >99.85% grade from ChemSolute) was added to each of the centrifuge bottles, which were then centrifuged (5 minutes at 3900 RPM). The supernatant was discarded.

[0277] The purified surface polymer-functionalized SiNP material was dried and ground by mortar and pestle to obtain homogeneous powders and subjected to thermogravimetric analysis. This method relies on thermally decomposing any components which are susceptible to such in the temperature interv al of the employed temperature ramp-up. In particular, for composite materials such as those containing an inorganic (silicon) core with an organic (polymer) shell, heating from room temperature to >500 °C will result in a mass loss which corresponds to the mass of organic (polymer) material prior to heating, while the remaining mass after heating may be prescribed to the inorganic (silicon) core. The obtained data allows for describing the percentage of the initial mass which was organic (surface polymer). Results are summarized in Table 9; for plots of remaining wt% as a function of temperature, as well as organic wt% as function of time before quenching each surface polymer formation, see Figs. 26 and 27.

[0278] Table 9. Data from thermogravimetric (TGA) analysis. The results obtained from thermogravimetric analysis show that the acidification of a reaction composition is an efficient method of quenching a surface polymer formation on initiator-coated SiNP substrate. While each material was subjected to their respective reaction composition for a total duration of 40 minutes, it was here shown that the act of acidifying a reaction composition had a distinct effect on its surface polymer-forming abili ty. A clear correlation was seen between the point in time for acidification and the resulting amount of polymer present on the SiNP material after reaction workup; when MSA was added at an earlier time after reaction onset, a lower organic weight% was obtained. Therefore, these data consolidate the quenching effect obtained by quenching a surface polymer formation by lowering of the pH of the reaction composition below the pKakh of the reaction composition. These results furthermore show that quenching can also successfully be performed on particulate material, nanoparticles in this case. The inventors therefore believe that a similar quenching efficiency would be obtained for other substrates classified as nanomaterials, such as nanopowders, nanofibers, nanotubes, or fullerenes.

[0279] Example 16

[0280] Reactivation of a quenched reaction composition for reuse in the surface polymer formation of initiator-coated silicon nanoparticle material as substrate

[0281] This example shows the concept of re-initiating surface polymer formation of a reaction composition which has been quenched by acidification (cf. Example 15). This allows for surface polymer formation on several consecutive batches of initiator-coated silicon nanoparticles (SiNP material) using a single reaction composition multiple time. The polymerization time was defined as the time between substrate addition and quenching by acidification, to reach a pH below the pKaFk of the copper / ligand complex.

[0282] Silicon nanoparticles (SiNP material) were subjected to pre-treatment with HF and subsequently grafting with 4-vinylbenzene chloride according to Example 15. The SiNP material was then dried and ground by mortar and pestle to obtain the purified VBC-functionalized SiNP material as a fine powder for usage as substrate in surface polymer formation.

[0283] In glass container Al containing a magnetic stirring bar a reaction composition were prepared in the following manner: 7.8 mL copper / ligand complex solution comprising tris[2-(dimethyl- aminojethyl] amine (MeeTREN, 14.6 pL, >98% grade from abcr or Alfa Aesar), DI -water (3.11 mL), and Cu(II) (324 mg / L, obtained from a solid copper source; no solid copper present in the resulting solution) were added, as well as DI- water (19.5 mL), iPrOH (70.0 mL, >99.8% grade from Chemsolute) and tBMA (7.5 mL, >98% grade, stabilized with MEHQ, from TCI Chemicals). In glass container B, sodium ascorbate (0.40 g, >98% grade from Sigma-Aldrich) was dissolved in DLwater (1.50 mL). The contents of container B were added to container Al, resulting in activation of the copper / ligand complex for polymer formation. The pH of the resulting reaction composition was measured to 9.9 with a pH meter (Metrohm 913 pH meter). 5 minutes after activation, while stirring at 400 rpm, a first batch of VBC-functionalized SiNP material (1.00 g) was added to container AL The reaction composition was subjected to 10 minutes of sonication, followed by 10 minutes of stirring. Immediately hereafter, the reaction composition was quenched by acidification through the addition of MSA (0.3 mL, >99% grade from Sigma- Aldrich), and the pH was ascertained to be < 4. 1 (the pKafb value of the Cu / MeeTREN complex). From this quenched reaction composition, the first batch of surface polymer-functionalized SiNP material was recovered by centrifugation (5 minutes at 3900 RPM) and decantation of the supernatant from glass container Al into a glass container A2. The quenched reaction composition, now situated in container A2, was re-initiated by basification through the careful addition of NaOH (aq., 10 M.) until the pH could be measured to be 9.9 (the value measured before acid addition). At this point, a second batch of VBC-functionalized SiNP material (1.00 g) was added to container A2. The reaction composition in container A2 was subjected to sonication, stirring, acidification, and centrifugation in an identical manner as that in container AL resulting in the formation of a second batch of surface polymer-functionalized SiNP material.

[0284] Both the first and second batch surface polymer-functionalized SiNP material were subjected to 2 cycles of workup as described in Example 15, resulting in two separate homogeneous powders, and subjected to thermogravimetric analysis. Results are summarized in Table 10; for plots of remaining wt% as a function of temperature, as well as organic wt% as function of time before quenching each polymerization, see Figs. 28-29. Table 10. Data from thermogravimetric analysis (TGA).

[0285] The data presented in Table 10 shows that the surface polymer formation on both the first and second substrate batch of SiNP material was successful, and that surface polymer formation occurred to similar extents. In conjunction with the results presented in Example 15 which demonstrated the successful quenching by acidification, these TGA data show that the basification of a reaction composition is efficient to restore the surface polymer-forming ability of a quenched reaction composition. Notably, in this example catalyst / ligand complex activator (sodium ascorbate) was only added prior to the first polymerization event, and not before the second. However, both surface polymer formations proceeded when the reaction composition pH was adjusted to pH 9.9. This means that reversible quenching was successful and may serve to “pause’’ the surface polymer formation, and that reverting to the initial (high) pH can serve to “resume” the surface polymer formation on SiNP due to the reassembling of the copper / ligand complex. Thus, the findings emphasize the reusability of a reaction composition following quenching and reinitiation. One batch of substrate may be subjected to surface polymer formation for a strictly controlled timeframe (depending on the time interval between polymerization start and acidification (quenching) of the reaction composition), the reaction composition can be basified (re-initiated), and a second batch of substrate can subjected to surface polymer formation for a second strictly controlled timeframe. The inventors believe that acidifying and basifying to quench and re-initiate, respectively, a reaction composition is possible for a number of cycles such that more than 2 substrate batches may be subjected to surface polymer formations in a single reaction composition. Thus, the quenching and re-initiation is believed to be applicable to a wide array of substrates for applications where strict control of the timeframe for surface polymer formation is desired. Example 17 . mer formation with conservation of itv by transfer from a reaction to a secondary

[0286] This example describes the transfer of a substrate from a reaction composition to a quenching composition during an ongoing polymerization. Furthermore, the ability to subsequently repolymerize the quenched substrate in the same reaction composition is shown, thus demonstrating the survival of the surface polymer chain end functionality during the quenching.

[0287] Silicon wafer substrates (3, same grade as described in Example 1) were pre-cleaned as described in Example 1, and polymerization initiators were attached to the surface as described in Example 2. The reaction composition was prepared as described in Example 4. The intrinsic pH of the reaction composition was measured to 9.6. The quenching composition was prepared in a separate glass container by adding Dl-water (484 mL), glycine (2807 mg, 99.5% grade, from Chemsolute), and methanesulfonic acid (MSA. > 99% grade from Sigma- Aldrich) was added until pH 2.35. The substrates were then immersed simultaneously in the reaction composition, and individually recovered from the reaction composition according to the following procedure. At minute 0, defined as 5 minutes after addition of (a solution of) catalyst activator (NaAsc), all substrates were immersed into the reaction composition. At subsequent timestamps, at minutes 5, 10. and 20, one substrate was transferred from the reaction composition to the quenching composition. In this way, 3 substrates subjected to the same reaction composition but for different durations of time are obtained, allowing for the assessment of the surface polymer growth as a function of time. Then, the 3 substrates were cleaned, and analyzed as described in Example 6. After analysis by ellipsometry, the 3 substrates were repolymerized by subjection to the reaction composition for 10 minutes, before transferring all substrates from the reaction composition to the quenching composition. Then, the 3 substrates were cleaned, and analyzed as described in Example 6. Surface polymer thicknesses recorded for individual substrates are shown in Table 11 and plotted in Fig. 30. Table 11. Comparison of surface polymer thicknesses obtained as function of time before transfer of substrates from the reaction composition to the quenching composition.

[0288] The results shown in Table 4 demonstrate that transfer of a substrate from a reaction composition to a quenching composition during an ongoing polymerization led to stopping the growth of the surface polymer. The substrate which was polymerized for 20 minutes before quenching was characterized by a higher thickness than the substrate which was polymerized for 10 minutes, and the substrate which was polymerized for 5 minutes before quenching was characterized by the lowest thickness. Furthermore, the ability to subsequently repolymerize the quenched substrate in the same reaction composition was demonstrated in that all 3 quenched substrates were characterized by a higher thickness after repolymerization, thus, demonstrating the survival of the surface polymer chain end functionality during the quenching. The results further demonstrated the usefulness of quenching outside the reaction composition using a liquid with a pH below the pKaH2 of the catalyst / ligand complex.

[0289] List of reference numerals

[0290] 100 System

[0291] 102 Substrate

[0292] 103 Substrate displacement device

[0293] 104 Reaction composition container

[0294] 105 Reaction composition

[0295] 106 Polymerization initiator chemistry container

[0296] 107 Polymerization initiator chemistry7

[0297] 109 Quenching container / Annealing oven

[0298] 111 Quenching solution / Oven gas

[0299] 1 14 Cleaning agent container

[0300] 116 Cleaning agent

[0301] 118 Roll-to-roll processor

[0302] 120 Roller

[0303] 121 Sending roll

[0304] 122 Receiving roll

[0305] 123 Flexible elongated substrate

[0306] 202 Dispenser

[0307] 204 Dispenser

[0308] 206 pH control agent

[0309] 208 O2 control agent

[0310] 210 Control unit

[0311] 216 pH sensor

[0312] 218 O2 sensor

[0313] 211 Recirculation circuit

[0314] 302 Process flow step for control of pH control agent dispenser

[0315] 304 Process flow step for control of pH control agent dispenser

[0316] 306 Process flow step for control of pH control agent dispenser

[0317] 308 Process flow step for control of pH control agent dispenser

[0318] 402 Process flow step for control of molecular oxygen control agent dispenser

[0319] 404 Process flow step for control of molecular oxygen control agent dispenser

[0320] 406 Process flow step for control of molecular oxygen control agent dispenser 408 Process flow step for control of molecular oxygen control agent dispenser

[0321] 501 Clean step in an example surface polymer formation flow

[0322] 503 Anneal step in an example surface polymer formation flow

[0323] 505 Clean step in an example surface polymer formation flow 507 Anneal step in an example surface polymer formation flow

[0324] 509 Formation step in an example surface polymer formation flow

[0325] 511 Clean step in an example surface polymer formation flow

[0326] 513 Anneal step in an example surface polymer formation flow

Claims

Claims1. A method for selectively quenching a surface polymer formation reaction comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising: at least one monomer; at least one ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex; at least one catalyst activator; and at least one solvent; for forming surface polymers from the polymerization initiator-modified sites; and quenching the surface polymer formation by lowering the pH of the reaction composition below the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst.

2. A method for selectively quenching a surface polymer formation reaction comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition having a pH above the pKattz of the complex formed between the at least one catalyst and the at least one ligand, the reaction composition comprising: at least one monomer; at least one ligand being a nitrogen-containing ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex; at least one catalyst activator; and at least one solvent being a mixture with water; and to form surface polymers from the polymerization initiator-modified sites; and reversibly quenching the surface polymer formation by lowering the pH of the reaction composition below the pKJfc of the complex formed between the at least one ligand and the at least one catalyst to decompose the complex formed between the at least one ligand and the at least one catalyst.

3. A method according to claim 1 or 2, wherein pH is lowered using an organic or an inorganic acidic substance.

4. A method according to any one of claims 1 to 2, wherein the acidic substance is selected from methanesulfonic acid (MSA), hydrochloric acid (HC1), sulfuric acid (H2SO4), phosphoric acid (H3PO4), 2.2.2-trifluoroacetic acid (TFA), -toluenesulfonic acid (pTSA). and nitric acid (HNO3), and combinations thereof.

5. A method according to any one of claims 1 to 43, wherein the reaction composition further comprises a buffer.

6. A method according to claim 5, wherein the buffer has more than one pKavalue.

7. A method according to claim 5 or 6, wherein the buffer is selected from carbonate buffer, glycine buffer, citrate buffer, phosphate buffer, acetate buffer, ammonium (ammonium chloride / ammonia) buffer, formate buffer, sodium ascorbate / ascorbic acid buffer, and Good’s buffers, and combinations thereof.

8. A method according to claim 7, wherein the Good's buffer is selected from MES, PIPES, MOPS, HEPES, CHES, CAPSO and CAPS, and combinations thereof.

9. A method according to any one of claims 1 to 8, wherein the reaction composition further comprises an inorganic salt.

10. A method according to claim 9, wherein the inorganic salt is selected from are NaCl, NaBr, KC1, KBr, MgCh, MgBn, CaCh, HC1, HBr, LiCl, LiBr, CaBn. CuBn and CuCh as well as combinations thereof.

11. A method according to any one of claims 1 to 10, wherein the substrate is selected from metal, glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composites, plastics, and particles.

12. A method according to claim 11, wherein the substrate is nanoparticle material, optionally including nanoparticles having a silicon core.

13. A method of initiating a surface polymer formation reaction comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising: at least one monomer; at least one ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex; at least one catalyst activator; and at least one solvent; for forming surface polymers from polymerization initiator-modified sites; wherein the pH of the reaction composition is below the pKath of the complex formed between the at least one ligand and the at least one catalyst; and initiating surface polymer formation from the polymerization initiator-modified sites by raising the pH of the reaction composition above the pKaH of the complex formed between the at least one ligand and the at least one catalyst.

14. A method of initiating a surface polymer formation reaction comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising: at least one monomer; at least one ligand being a nitrogen-containing ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex; at least one catalyst activator; and at least one solvent being a mixture with water; for forming surface polymers from polymerization initiator-modified sites; wherein the pH of the reaction composition is below the pKaH of the complex formed between the at least one ligand and the at least one catalyst; and initiating surface polymer formation from the polymerization initiator-modified sites by raising the pH of the reaction composition above the pKJb of the complex formed between the atleast one ligand and the at least one catalyst to reassemble the complex formed between the catalyst and the ligand.

15. A method according to claim 13 or 14, wherein the surface polymer formation is re-initiated by raising the pH of the reaction composition above the pKaHi of the complex formed between the at least one ligand and the at least one catalyst.

16. A method according to any one of claims 13 to 15, wherein the pH is raised using an alkaline substance.

17. A method according to claim 16, wherein the alkaline substance is potassium hydroxide (KOH), lithium hydroxide (LiOH) tripotassium phosphate (K3PO4), sodium carbonate (Na2CO3), or sodium ethoxide (CHsCH2ONa), and combinations thereof.

18. A method according to any one of claims 13 to 17, wherein the reaction composition further comprises a buffer.

19. A method according to claim 18, wherein the buffer has more than one pKavalue.

20. A method according to claim 18 or 19, wherein the buffer is selected from carbonate buffer, glycine buffer, citrate buffer, phosphate buffer, acetate buffer, ammonium (ammonium chloride / ammonia) buffer, formate buffer, sodium ascorbate / ascorbic acid buffer, and Good’s buffers, and combinations thereof.

21. A method according to claim 20, wherein the Good’s buffer is selected from MES, PIPES, MOPS, HEPES, CHES, CAPSO and CAPS, and combinations thereof.

22. A method according to any one of claims 13 to 21, wherein the oxygen concentration of the reaction composition is controlled during the initiation of the surface polymer formation.

23. A method according to claim 22, wherein the oxygen concentration is below a partial pressure of 25 hPa.

24. A method according to any one of claims 13 to 23, wherein the substrate is selected from metal, glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composites, plastics, and particles.

25. A method according to claim 24, wherein the substrate is nanoparticle material, optionally including nanoparticles having a silicon core.

26. A method for forming surface polymers comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising: at least one monomer; at least one ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex; at least one catalyst activator; and at least one solvent; to form surface polymers from the initiator-modified sites; quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKJH of the complex formed between the at least one ligand and the at least one catalyst to decompose the complex formed between the at least one ligand and the at least one catalyst; and raising the pH of the reaction composition above the pKJ-fi of the complex formed between the at least one ligand and the at least one catalyst to re-initiate the formation of surface polymers.

27. A method for forming surface polymers comprising: bringing at least a portion of a polymerization initiator-modified substrate into contact with a reaction composition, the reaction composition comprising: at least one monomer; at least one ligand being a nitrogen-containing ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex; at least one catalyst activator; and at least one solvent being a mixture with water;wherein the reaction composition has a pH above the pKJH of the complex formed between the at least one catalyst and the at least one ligand; to form surface polymers from the initiator-modified sites; reversibly quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst to decompose the complex formed between the at least one ligand and the at least one catalyst; and raising the pH of the reaction composition above the pKJ-b of the complex formed between the at least one ligand and the at least one catalyst to reassemble the complex formed between the at least one ligand and the at least one catalyst to re-initiate the formation of surface polymers.

28. A method for forming surface polymers comprising: providing a reaction composition comprising: at least one monomer; a least one ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex; at least one catalyst activator; and at least one solvent; bringing at least a portion of a first polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said first substrate; quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst; withdrawing said first substrate from the reaction composition; re-initiating the formation of surface polymers by raising the pH of the reaction composition above the pKal b of the complex formed between the at least one ligand and the at least one catalyst; and bringing at least a portion of a second polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said second substrate; and optionally quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKJfo of the complex formed between the at least one ligand and the at least one catalyst prior to withdrawing said second substrate from the reaction composition.

29. A method for forming surface polymers comprising: providing a reaction composition comprising: at least one monomer; a least one ligand being a nitrogen-containing ligand; at least one catalyst, wherein the at least one ligand and the at least one catalyst form a complex; at least one catalyst activator; and at least one solvent being a mixture with water; the reaction composition having a pH above the pKaH2 of the complex formed between the ligand and the catalyst; bringing at least a portion of a first polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said first substrate; reversibly quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKJrb of the complex formed between the at least one ligand and the at least one catalyst to decompose the complex formed between the at least one catalyst and the at least one ligand; withdrawing said first substrate from the reaction composition; re-initiating the formation of surface polymers by raising the pH of the reaction composition above the pKJfc of the complex formed between the at least one ligand and the at least one catalyst to reassemble to complex formed between the at least one catalyst and the at least one ligand; and bringing at least a portion of a second polymerization initiator-modified substrate into contact with the reaction composition to form surface polymers on said second substrate; and optionally reversibly quenching the formation of surface polymers by lowering the pH of the reaction composition below the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst to decompose the complex formed between the catalyst and the ligand prior to withdrawing said second substrate from the reaction composition.

30. A method according to anyone of claims 26 to 29, wherein the pH of the reaction composition is raised above the pIGHi of the complex formed between the at least one ligand and the at least one catalyst.

31. The method according to anyone of claims 26 to 29, wherein the pH is lowered using an acidic substance.

32. The method according to claim 31, wherein the acidic substance is an organic or an inorganic acidic substance.

33. The method according to claim 32, wherein the acidic substance is selected from methanesulfonic acid (MSA), hydrochloric acid (HC1), sulfuric acid (H2SO4), phosphoric acid (H3PO4), 2,2,2-trifluoroacetic acid (TFA), / 2-toluenesul Tonic acid (pTSA), and nitric acid (HNO3), and combinations thereof.

34. A method according to any one of claims 26 to 29, wherein the pH is raised using an alkaline substance.

35. A method according to claim 34, wherein the alkaline substance is alkaline substance is potassium hydroxide (KOH), lithium hydroxide (LiOH) tripotassium phosphate (K3PO4), sodium carbonate (Na2COs), or sodium ethoxide (CHsCH2ONa), and combinations thereof.

36. A method according to any one of claims 26 to 29, wherein the reaction composition further compnses a buffer.

37. A method according to claim 36, wherein the buffer has more than one pKavalue.

38. A method according to claim 36 or 27, wherein the buffer is selected from carbonate buffer, glycine buffer, citrate buffer, phosphate buffer, acetate buffer, ammonium (ammonium chloride / ammonia) buffer, formate buffer, sodium ascorbate / ascorbic acid buffer, and Good’s buffers, and combinations thereof.

39. A method according to claim 28, wherein the Good’s buffer is selected from MES, PIPES, MOPS, HEPES, CHES, CAPSO and CAPS, and combinations thereof.

40. A method according to any one of claims 26 to 29, wherein the oxygen concentration of the reaction composition is controlled during the re-initiation of the surface polymer formation composition.

41. A method according to claim 30, wherein the oxygen concentration is kept below a partial pressure of 25 hPa.

42. A method according to any one of claims 26 to 29, wherein the substrate is selected from metal, glass, carbon, graphite, graphene, carbon black, monoclays, ceramics, composites, plastics, and particles.

43. A method according to claim 42, wherein the substrate is nanoparticle material, optionally including nanoparticles having a silicon core.

44. A method according to any one of claims 1 to 43, wherein the the ligand is selected from N,N,N', N”. A'"-pentamethyldiethylene-lnamine (PMDETA), tris [2-(dimethylamino)ethyl] amine (MeeTREN), tris(2-aminoethyl)amine (TREN), tris(2-pyridyl- methy l)amine (TPMA), 1 , 1 ,4, 7, 10, 10-hexamethy Itri ethylenetetramine (HMTETA), tetramethylethylenediamine (TMEDA), 1,4, 8.11 -tetramethyl- 1.4.8.11-tetraazacyclotetradecane(MerCy clam), and 2.2’-bipyridyl (BiPy) as well as combinations thereof; the catalyst is selected from copper (Cu), iron (Fe), ruthenium (Ru), or titanium (Ti); the catalyst activator is an oxygen scavenger selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid as well as combinations thereof; and the oxygen control agent is an oxygen scavenger selected from sodium ascorbate (NaAsc), ascorbic acid (Asc), hydrazine, hydrazine hydrate, sodium thiosulfate, sodium sulfite, sodium dithionite, glucose with GOx, and pyrogallic acid.

45. A system for forming surface polymers on a substrate according to any one of claims 1 to 44, the system comprising: a reaction composition container for containing a reaction composition; and a substrate displacement device for bringing at least a portion of a polymerization initiator- modified substrate into contact with the reaction composition in the reaction compositioncontainer, and for removing the polymerization initiator-modified substrate from the reaction composition; and a means for quenching the surface polymer formation reaction on the substrate; wherein the substrate displacement device is configured to maintain the portion of the polymerization initiator-modified substrate in contact with the reaction composition to enable surface polymers to be formed on the portion of the polymerization initiator-modified substrate.

46. A system according to claim 45, further comprising a pH control agent dispenser for providing the acid or base for the quenching and / or the initiating and / or the re-initiating.

47. A system according to claim 46, wherein the pH control agent dispenser is enabled for quenching the surface polymer formation reaction on the substrate following withdrawal of the substrate from the reaction composition.

48. A system according to claim 45, further comprising a quenching container for quenching the surface polymer formation by lowering the pH of any reaction composition remaining on the surface of the polymerization initiator-modified substrate below the pKaH2 of the complex formed between the at least one ligand and the at least one catalyst, and wherein the substrate displacement device is configured to move the polymerization initiator-modified substrate from the reaction composition chamber to the quenching container.

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