Method of applying primer for self-assembled layers and articles

Abstract

A method of making an article is described comprising providing a substrate; applying a primer layer to the substrate; wherein the primer layer comprises the reaction product of a polymerizable resin comprising at least one monomer with at least two ethylenically unsaturated groups; and applying a plurality of layers deposited by layer-by-layer self-assembly to the primer layer. An article is described comprising a substrate; a primer layer disposed on the substrate; wherein the primer layer comprises the reaction product of a polymerizable resin comprising at least one monomer with at least two ethylenically unsaturated groups; and an ionically bonded polymer matrix disposed on the primer layer.

Description

[0001] METHOD OF APPLYING PRIMER FOR SELF-ASSEMBLED LAYERS

[0002] AND ARTICLES

[0003] Summary

[0004] In one embodiment, a method of making an article is described comprising providing a substrate; applying a primer layer to the substrate; wherein the primer layer comprises the reaction product of a polymerizable resin comprising at least one monomer with at least two ethylenically unsaturated groups; and applying a plurality of layers deposited by layer-by-layer self-assembly to the primer layer.

[0005] In another embodiment, an article is described comprising a substrate; a primer layer disposed on the substrate; wherein the primer layer comprises the reaction product of a polymerizable resin comprising at least one monomer with at least two ethylenically unsaturated groups; and a plurality of layers deposited by layer-by-layer self-assembly disposed on the primer layer.

[0006] In another embodiment, an article is described comprising a substrate; a primer layer disposed on the substrate; wherein the primer layer comprises the reaction product of a polymerizable resin comprising at least one monomer with at least two ethylenically unsaturated groups; and an ionically bonded polymer matrix of at least two different organic polymers.

[0007] In some embodiments, the plurality of layers comprise at least one polycationic polymer and at least one polyanionic polymer. In some embodiments, the primer layer has a thickness less than 1 micron, 750 nm, 500 nm, or 250 nm.

[0008] Brief Description of the Drawings

[0009] Fig. 1 is a cross sectional view of an illustrative article 500 comprising a substrate 550 and a plurality of layers deposited by layer-by-layer self-assembly 510, disposed on substrate 550;

[0010] Fig. 2 is a cross sectional view of an illustrative article 501 comprising a substrate 551 including a primer 560 and a plurality of layers deposited by layer-by-layer self-assembly 510, disposed on primer 560;

[0011] Fig. 3 is a cross sectional view of an embodiment of a plurality of bi-layers deposited by layer- by-layer self-assembly 510.

[0012] Detailed Description

[0013] As used in this application:

[0014] "polymer" means organic polymers and copolymers (i.e., polymers formed from two or more monomers or comonomers, including terpolymers, for example), as well as copolymers or polymers that can be formed in a miscible blend by, for example, coextrusion or reaction, including transesterification, for example. Block, random, graft, and alternating polymers are included. “polyelectrolytes” are organic polymers whose repeating units bear an electrolyte group. The electrolyte groups can dissociate in aqueous solutions (water), making the polymers charged. Polyelectrolyte properties are thus similar to both electrolytes (salts) and polymers (high molecular weight compounds) and are sometimes called polysalts. Like salts, their solutions are electrically conductive. “Strong polyelectrolytes” possess permanent charges across a wide range of pH (e.g., polymers containing quaternary ammonium groups or sulfonic acid groups). “Weak polyelectrolytes” possess a pH-dependent level of charge (e.g. polymers containing primary, secondary, or tertiary amines, or carboxylic acids);

[0015] “polycation” refers to a polyelectrolyte that is positively charged in aqueous solution (water); “poly anion” refers to a poly electrolyte that is negatively charged in aqueous solution (water);

[0016] Written Description

[0017] With reference to Fig. 1, an illustrative comparative article 500 comprises substrate 550 and a plurality of layers 510 disposed on the substrate 550.

[0018] With reference to Fig. 2, an illustrative article 501 of the present invention comprises substrate 551 and a plurality of layers 510. A primer 560 is disposed between the substrate 551 and plurality of layers 510.

[0019] The primer 560 typically has a thickness no greater than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 micron. In some embodiments, the primer has a thickness of at least 25, 50, 75 or 100 nm. In some embodiments, the primer has a thickness of less than 1 micron, 750 nm, 500 nm, or 250 nm.

[0020] The primer improves the adhesion between the substrate and the plurality of layers 510. The adhesion can be determined by various techniques such as the tape test described in the forthcoming examples. The inclusion of the primer results in the percentage of the surface area of the plurality of layers 510 (e.g. layer by layer coating) that is damaged when evaluated with the tape test being less than the control, i.e. the same substrate and plurality of layers without the primer. In some embodiments, the percentage of surface area of the plurality of layers 510 (e.g. layer by layer coating) that is damaged when evaluated with the tape test is less than 35, 30, 25, 30, 15, 10, 5 or 1%.

[0021] The plurality of layers disposed on the substrate comprise at least two layers deposited by what is commonly referred to as a “layer-by-layer self-assembly process”. This process is commonly used to assemble films or coatings of oppositely charged polyions such as polyelectrolytes electrostatically, but other functionalities such as hydrogen bond donor / acceptors, metal ions / ligands, and covalent bonding moieties can be the driving force for film assembly. Typically, this deposition process involves exposing the substrate having a surface charge, to a series of liquid solutions, or baths. This can be accomplished by immersion of the substrate into liquid baths (also referred to as dip coating), spraying, spin coating, roll coating, inkjet printing, and the like. Exposure to the first polyelectrolyte (bath) liquid solution, which has charge opposite that of the substrate, results in charged species near the substrate surface adsorbing quickly. This establishes a concentration gradient and draws more polyelectrolyte from the bulk solution to the surface. Further adsorption occurs until a sufficient layer has developed to mask the underlying charge and reverse the net charge of the substrate surface. In order for mass transfer and adsorption to occur, this exposure time is typically on the order of minutes. The substrate is then removed from the first polyion liquid solution (e.g. “bath”), and is then exposed to a series of water rinse baths to remove any physically entangled or loosely bound poly electrolyte. Following these rinse (e.g. bath) liquid solutions, the substrate is then exposed to a second polyelectrolyte liquid solution, which has charge opposite that of the first polyion (e.g. bath) liquid solution. Once again adsorption occurs, since the surface charge of the substrate is opposite that of the second (e.g. bath) liquid solution. Continued exposure to the second polyion (e.g. bath) liquid solution then results in a reversal of the surface charge of the substrate. A subsequent rinsing can be performed to complete the cycle. This sequence of steps is said to build up one layer pair, also referred to herein as a “bi-layer” of deposition and can be repeated as desired to add further layer pairs to the substrate.

[0022] Some examples of suitable processes include those described inKrogman et al., US 8,234,998; Hammond-Cunningham et al., US2011 / 0064936; and Nogueira et al., US 8,313,798. Further layer-by layer dip coating can be conducted using a Strato Sequence VI (nanoStrata Inc., Tallahassee, FL) dip coating robot.

[0023] With reference to Fig. 3, the plurality of layers 510, deposited by layer-by-layer self-assembly, comprise one or more bi-layers comprising a poly cation (e.g. polyelectrolyte) monolayer 512 and a polyanion (e.g. polyelectrolyte) monolayer 513.

[0024] Suitable polyelectrolytes include polycationic polymers (i.e. polycations) such as linear and branched poly(ethyleneimine), poly(allylamine hydrochloride) (PAH), polyvinylamine, chitosan, polyaniline, polypyrrole, polyamidoamine, poly(vinylbenzyltriamethylamine), polydiallyldimethylammonium chloride, poly(dimethylaminoethyl methacrylate), and poly(methacryloylamino)propyl-trimethylammonium chloride.

[0025] Suitable polyanionic polymers include, but are not limited to, poly(vinyl sulfate), poly(vinyl sulfonate), poly(acrylic acid) (PAA), poly(methacrylic acid), polystyrene sulfonate), dextran sulfate, heparin, hyaluronic acid, carrageenan, carboxymethylcellulose, alginate, sulfonated tetrafluoroethylene based fluoropolymers such as Nafion®, poly(vinyl-phosphoric acid), and poly(vinylphosphonic acid).

[0026] The molecular weight of the polyelectrolyte can vary, ranging from about 1,000 g / mole to about 1,000,000 g / mole. In some embodiments, the molecular weight (Mw or Mn) of the polyelectrolyte is at least 5,000; 10,000; 15,000; 20,000 or 25,000 g / mole. In some embodiments, the molecular weight (Mw or Mn) of the polyelectrolyte is no greater than 100,000; 75,000; or 50,000 g / mole. The plurality of layers deposited by layer-by-layer self-assembly may optionally further comprise an organic light absorbing compound, an organic light stabilizing compound, or a combination thereof dispersed within and preferably covalently bonded to a polyelectrolyte, as described is US 9,902,869; incorporated herein by reference.

[0027] The thickness of a bi-layer and the number of bi-layers are selected to achieve the desired (e.g. optical, barrier, or protection) properties, typically using the minimum total thickness of self-assembled layers and / or the minimum number of layer-by-layer deposition steps. In some embodiments, the thickness of a bi-layer, the number of bi-layers per stack, the number of stacks, and the thickness of each stack are selected to achieve the desired optical properties using the minimum total thickness of selfassembled layers and / or the minimum number of layer-by-layer deposition steps. The thickness of each bi-layer typically ranges from about 1 nm to 100 nm. The number of bi-layers per stack typically ranges from about 1 to 200. In some embodiments, the number of bilayers per stack is at least 2, 5, 10, 20, or 30. The number of stacks is typically at least 1, 2, 3, or 4 and no greater than 20, 19, 18, 17, or 15. The thickness of a stack is typically at least 25 nm, 35 nm, 45 nm, 55 nm, 65 nm, 75 nm, or 85 nm and no greater than 5, 6, 7, 8, 9, or 10 microns. In some embodiments, the thickness of a stack is no greater than 500 nm, 400 nm, 300 nm, 250 nm, 200 nm, or 150 nm. In other embodiments, the number of bi-layers is selected to achieve the desired transmission in combination with mechanical durability. In this embodiment, the thickness of a bi-layer and number of bi-layers may approach the maximum values. Further, this embodiment may utilize a single stack of low or high refractive index that may be index matched to the substrate or coating to which it is applied. In typical embodiments, the resulting stack may be characterized as an ionically bonded polymer matrix of at least two organic polymers.

[0028] The substrate 550 is typically a plate or continuous film having a thickness of at least 20, 30, 40, or 50 microns to 1, 2, 3, 4, or 5 cm. In more typical embodiments, the thickness of the substrate is no greater than 30, 20, or 10 mm. Further, thinner substrates may be employed for embodiments wherein the substrate is reinforced by a carrier such as a removable liner.

[0029] In some embodiments, substrate 550 is an inorganic substrate, such as glass. In other embodiments, substrate 550 is an organic polymer material. In yet other embodiments, the substrate is a composite or multilayer substrate that may comprises both organic polymer material(s) and inorganic materials.

[0030] Suitable organic polymer (e.g. film) materials include homopolymers, copolymers, blends, multilayer films including multilayer optical films, and multilayer laminates of any polymeric materials including for example polyester (e.g., polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate glycol), polycarbonate, allyldiglycol carbonate, acrylics (e.g., polymethylmethacrylate (PMMA)), polystyrene, polysulfone, polyether sulfone, homoepoxy polymers, epoxy addition polymers with polydiamines and / or polydithiols, polyamides (e.g., nylon 6 and nylon 6,6), polyimides, polyolefins (e.g., polyethylene including low density polyethylene and polypropylene), olefinic copolymers (e.g., polyethylene copolymers), polyurethanes, polyureas, cellulose esters (e.g., cellulose acetate, cellulose triacetate, and cellulose butyrate), fluoropolymers, cyclic olefin copolymers (e.g. polyethylene / norbomene copolymers), and combinations thereof.

[0031] Inorganic substrates include for example insulators / dielectrics, semiconductors, or conductors. Inorganic substrates (e.g. dielectrics) can be amorphous or crystalline and include, for example, glass (e.g. float glass, soda lime glass, borosilicate glass), quartz, fused quartz, sapphire, yttria, and other transparent ceramics. Inorganic substrates (e.g. semiconductors) include for example silicon, germanium, Group III / Group V semiconductors (e.g. gallium arsenide) Group II / VI semiconductors, Group IV / VI semiconductors, or Group IV semiconductors (e.g. silicon carbide). Inorganic substrates (e.g. conductors) include for example transparent conductive oxides (TCOs) such as indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO) or metals such as gold, silver, aluminum, copper, iron, or alloys such as stainless steel.

[0032] Prior to applying the primer to the substrate, the substrate is typically subject to corona or other surface treatment that provides a negative charge on the surface of the substrate.

[0033] A primer is applied to the surface treated (i.e. charged) substrate. In some embodiments, the primer comprises a polymerizable resin in combination with an organic solvent to form a dilute solution. In some embodiments, the amount of organic solvent is typically at least 10, 20, 30, or 40 wt.%. In some embodiments, the amount of organic solvent is no greater than 70, 65, or 60 wt.%. In other embodiments, the polymerizable resin may be solventless.

[0034] In some embodiments, the polymerizable resin is typically applied as a dilute solution such as by spin coating onto the (e.g. corona treated) surface, dried, and cured by exposure to actinic radiation. The polymerizable resin may be applied by other techniques such as a wire-wound (e.g. Mayer) rod, notch bar, doctor blade, or inkjet printing.

[0035] The polymerizable resin comprises various ethylenically unsaturated monomers. The term ethylenically unsaturated refers to vinyl and “(methjacryl” that includes methacrylate, acrylate, methacrylamide, acrylate, or acrylamide. Ethylenically unsaturated monomers typically have a molecular weight no greater than 5000, 2500, 2000, 1500, or 1000 g / mole.

[0036] Unlike applying a layer of preformed (e.g. acrylic) polymer to the substrate, it is surmised that the monomers may partially dissolve and thus penetrate into the surface of the organic polymer substrate. After curing, the polymerizable resin composition or the primer layer may be characterized as a polymer. When the polymerizable resin comprises greater than 50 wt.% of (methjacryl monomer the polymer may be characterized as a (methjacrylic) polymer.

[0037] In some embodiments, the polymerizable resin comprises at least one monomer having at least 2 or 3 ethylenically unsaturated (e.g. (methjacrylate) groups. In some embodiments, the monomer has no greater than 6, 5, 4, or 3 ethylenically unsaturated (e.g. (meth)acrylate) groups. In some embodiments, the monomer lacks aromatic moieties and may be characterized as aliphatic or cycloaliphatic. Polymerizable resin comprising about 80 wt.% ethoxylated (3) bisphenol and 16 wt.% N,N- dimethylacrylamide (DMA), and photoinitiator was found not to improve the adhesion of bi-layer of PDAC and PSS with PMMA substrate. However, it is contemplated that such polymerizable resin may be a suitable primer for other substrates.

[0038] Examples of useful multifunctional (meth)acrylates include, but are not limited to, di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates, such as 1,6-hexanediol di(meth)acrylate, tricyclodecanedimethanol diacrylate, 2-phenoxyethyl acrylate, polyethylene glycol) di(meth)acrylates, polybutadiene di(meth)acrylate, polyurethane di(meth)acrylates, propoxylated glycerin tri(meth)acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, and mixtures thereof.

[0039] In some embodiments, the monomer lacks cyclic groups and has a molecular weight per ethylenically unsaturated (e.g. (meth)acrylate)) group of no greater than 100 g / mole, such as in the case of pentaerythritol triacrylate or hexanediol diacrylate.

[0040] In other embodiments, the monomer comprises a cycloaliphatic group comprising greater than 6 carbon atoms, such as in the case of tricyclodecanedimethanol diacrylate.

[0041] In some embodiments, the amount of monomer having at least 2 or 3 ethylenically unsaturated groups is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 99% of the ethylenically unsaturated monomers of the polymerizable resin. Thus, the cured polymerizable resin comprises the same concentration of polymerized units of such monomer.

[0042] The polymerizable resin of the primer typically comprises polar monomers. Representative polar monomers include for example acid-functional monomers, hydroxyl functional monomers, nitrogencontaining monomers, and combinations thereof.

[0043] In some embodiments, the polymerizable resin of the primer layer comprises at least 1, 2, 3, 4, or 5 wt.% of polar monomers. In some embodiments, the polymerizable resin comprises no greater than 20, 15, or 10 wt.% of polar monomers. Thus, the cured polymerizable resin comprises the same concentration of polymerized units of such monomer.

[0044] Useful acid functional monomers include, but are not limited to, those selected from ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids, ethylenically unsaturated phosphonic acids, and mixtures thereof. Examples of such compounds include those selected from acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, citraconic acid, maleic acid, oleic acid, b -carboxy ethyl (meth)acrylate, 2-sulfoethyl methacrylate, styrene sulfonic acid, 2-acrylamido-2- methylpropanesulfonic acid, vinylphosphonic acid, and mixtures thereof. Representative examples include N-vinylpyrrolidone; N-vinylcaprolactam; acrylamide; mono- or di-N-alkyl substituted acrylamide; t-butyl acrylamide; dimethylaminoethyl acrylamide; and N-octyl acrylamide.

[0045] Representative hydroxy -functional monomers include 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2- ethoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate, 2- methoxyethyl (meth)acrylate, and polyethylene glycol mono(meth)acrylates.

[0046] The polar monomer may include a single acid-functional monomer, a single hydroxyl functional monomers, a single nitrogen-containing monomers, a combination of monomers within a class or a combination of monomers of different classes.

[0047] In some embodiments, the polar monomer is acrylic acid, N,N-dimethylacrylamide (DMA), or a combination thereof.

[0048] Monomers such as pentaerythritol triacrylate or hexanediol diacrylate and tricyclodecanedimethanol diacrylate may be characterized as high Tg monomers, i.e. a (meth)acrylate monomer when reacted to form a homopolymer has a Tg greater than 0°C. The high Tg monomer more typically has a Tg greater than 25°C, 50°C, or 100°C.

[0049] In some embodiments, the polymerizable resin of the primer layer comprises one or more low Tg (meth)acrylate monomers, i.e. a (meth)acrylate monomer that when reacted to form a homopolymer has a Tgno greater than 0°C. In some embodiments, the low Tg monomer has a Tgno greater than -5°C, or no greater than -10°C. The Tg of these homopolymers is often greater than or equal to -80°C, greater than or equal to -70°C, greater than or equal to -60°C, or greater than or equal to -50°C. The inclusion of low Tg monomer can improve the conformability of the primer layer.

[0050] The low Tg monomer may have the formula H2C=CR1C(O)OR8, wherein R1is H or methyl and R8is an alkyl with 1 to 22 carbons or a heteroalkyl with 2 to 20 carbons and 1 to 6 heteroatoms selected from oxygen or sulfur. The alkyl or heteroalkyl group can be linear, branched, cyclic, or a combination thereof.

[0051] Representative low Tg monomers include for example ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2- methylbutyl acrylate, 2-ethylhexyl acrylate, 4-methyl-2 -pentyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, isotridecyl acrylate, octadecyl acrylate, and dodecyl acrylate. Low Tg heteroalkyl acrylate monomers include, but are not limited to, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate.

[0052] In some embodiments, the polymerizable resin of the primer layer comprises at least one low Tg monomer(s) having an alkyl group with 6 to 20 carbon atoms. In some embodiments, the low Tg monomer has an alkyl group with 7 or 8 carbon atoms. Exemplary monomers include, but are not limited to, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, 2-octyl (meth)acrylate, isodecyl (meth)acrylate,-and lauryl (meth)acrylate. In some embodiments, the monomer is an ester of (meth)acrylic acid with an alcohol derived from a renewable source, such as 2-octyl (meth)acrylate.

[0053] The polymerizable resin of the primer layer may optionally comprise high Tg mono(meth)acrylate monomer(s).

[0054] Representative high Tg monofunctional alkyl (meth)acrylate monomers include for example t- butyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, stearyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, isobomyl acrylate, isobomyl methacrylate, norbomyl (meth)acrylate, phenoxy ethyl acrylate, benzyl methacrylate, 3,3,5 trimethylcyclohexyl acrylate, cyclohexyl acrylate, and propyl methacrylate or combinations.

[0055] The Tg of the homopolymer of various monomers is known and is reported in various handbooks. The Tg of some illustrative monomers is reported in WO 2016 / 094277, incorporated herein by reference.

[0056] In some embodiments, the polymerizable resin of the primer layer comprises at least 5, 10, 15, 20 or 25 wt-% of monofunctional alkyl (meth)acrylate monomer(s). In some embodiments, the polymerizable resin of the primer layer comprises no greater than 50, 45, 40, 35, 30, 25, or 20 wt.-% of monofunctional alkyl (meth)acrylate monomer(s). The monofunctional alkyl (meth)acrylate monomer(s) may be low Tg monomers, high Tg monomers, or a combination thereof. Thus, the cured polymerizable resin comprises the same concentration of polymerized units of such monomer.

[0057] The polymerizable resin of the primer may optionally comprise additives provided the polymerizable resin provides an improvement in adhesion, as demonstrated by the tape test further described in the examples. Common additives include polymerizable or unpolymerizable additives such as ultraviolet light absorbers (UVA) that comprises a benzotriazole, benzophenone, or triazine group, hindered amine light stabilizers (HALS) and combinations thereof in amount ranging from about 2-10%. In other embodiments, the polymerizable resin of the primer lacks such light absorbers (UVA) and hindered amine light stabilizers (HALS).

[0058] The polymerizable composition of the primer can be polymerized by various techniques, yet is preferably polymerized by solventless radiation polymerization, including processes using electron beam, gamma, and especially ultraviolet light radiation. In this (e.g. ultraviolet light radiation) embodiment, generally little or no methacrylate monomers are utilized. Thus, the primer may comprise zero or no greater than 10, 5, or 1 wt.-% of polymerized units of monomer having a methacrylate group.

[0059] When the polymerizable composition of the primer is cured by photocuring, the polymerizable composition typically comprises a photoinitiator. Useful photoinitiators include benzoin ethers such as benzoin methyl ether and benzoin isopropyl ether; substituted acetophenones such as 2,2-dimethoxy-2- phenylacetophenone photoinitiator, available under the trade name IRGACURE 651 orESACUREKB-1 photoinitiator (Sartomer Co., West Chester, PA), and dimethylhydroxyacetophenone; substituted a-ketols such as 2- methyl-2 -hydroxy propiophenone; aromatic sulfonyl chlorides such as 2-naphthalene-sulfonyl chloride; photoactive oximes such as l-phenyl-l,2-propanedione-2-(O-ethoxy-carbonyl)oxime; mono- or bis- acylphosphine oxides such as LUCIRIN TPO or OMNIRAD 819. Suitable photoinitiators are typically present in an amount of from 0.1 to 1.0 wt.-%.

[0060] The polymerizable resin is sufficiently transparent such that it may be irradiated with activating UV radiation having a UVA maximum in the range of 280 to 425 nanometers to polymerize the monomer component(s). UV light sources can be of various types. Low light intensity sources, such as blacklights, generally provide intensities ranging from 0.1 or 0.5 mW / cm2(millwatts per square centimeter) to 10 mW / cm2(as measured in accordance with procedures approved by the United States National Institute of Standards and Technology as, for example, with a UVIMAP UM 365 L-S radiometer manufactured by Electronic Instrumentation & Technology, Inc., in Sterling, VA). High light intensity sources generally provide intensities greater than 10, 15, or 20 mW / cm2ranging up to 450 mW / cm2or greater. In some embodiments, high intensity light sources provide intensities up to 500, 600, 700, 800, 900 or 1000 mW / cm2. UV light to polymerize the monomer component(s) can be provided by various light sources such as light emitting diodes (LEDs), blacklights, medium pressure mercury lamps, etc., or a combination thereof. The monomer component(s) can also be polymerized with higher intensity light sources as available from Fusion UV Systems Inc., Gaithersburg, MD. The UV exposure time for polymerization and curing can vary depending on the intensity of the light source(s) used. For example, complete curing with a low intensity light course can be accomplished with an exposure time ranging from about 30 to 300 seconds, whereas complete curing with a high intensity light source can be accomplished with shorter exposure time ranging from about 5 to 20 seconds. Partial curing with a high intensity light source can typically be accomplished with exposure times ranging from about 2 seconds to about 5 or 10 seconds.

[0061] In some embodiments, both the substrate and the plurality of layers deposited by layer-by-layer self-assembly (i.e. ionically bonded polymer matrix of at least two organic polymers) are light transmissive to visible light (400 to 700 nm), to visible light (400 to 700 nm), typically exhibiting at least 85% or 90% transmission.

[0062] Organic polymer films having a high transmission of visible light including UV, IR and visible mirrors may be used in architectural applications, greenhouse applications, window films, paint protection films, solar power applications, lighting, fenestration products (i.e., products that fill openings in a building, such as windows, doors, skylights, or curtain walls, e.g., that are designed to permit the passage of light), solar light tube products and other day lighting systems for transporting sunlight to interior rooms, and other applications. In other embodiments, the substrates described herein may be used in commercial graphics films (e.g. films for billboards, building exteriors, signage, automobiles, mass transit vehicles, etc.), traffic signage, and protection films such as car wrap films.

[0063] The plurality of layers deposited by layer-by-layer self-assembly typically do not comprise polyelectrolytes alternated with inorganic oxide nanoparticles comprising a phosphorous-containing surface treatment, such as described in W02015-095317. When the bilayers comprise inorganic nanoparticles, the concentration of inorganic nanoparticles is typically at least 30 wt.-% of the dried bilayer, or totality of self-assembled layers. However, it is contemplated that a portion of the layers may comprise inorganic oxides particles. Further, it may be advantageous to coat the final bilayer surface with a coating (e.g. hardcoat) comprising inorganic oxide nanoparticles. In these embodiments, the plurality of layers deposited by layer-by-layer self-assembly, ionically bonded polymer matrix of at least two organic polymers, and article typically comprises less than 25, 20, 15, 10, 5, 1 or 0.5 wt.% of inorganic nanoparticles.

[0064] Advantages and embodiments of this disclosure are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure. All materials are commercially available or known to those skilled in the art unless otherwise stated or apparent.

[0065] Examples

[0066] Table 1. List of materials and suppliers

[0067] Table 2. Resins for injection molded polymer substrates (approximately 4.5”x7”x0.15”)

[0068] Preparation of primer In a 4-oz amber jar, 24.92 grams (83 wt.% solids) of SR444, 3.91 grams (13 wt.% solids) of DMA, 1.17 grams (3.9 wt.% solids) of Esacure One, and 30.00 grams of Carbitol (2-(2-ethoxyethoxy)ethanol) were added. Once combined, the jar was sealed and vigorously shaken until the contents were well mixed and the initiator completely dissolved. The jar was then allowed to sit and degas any entrained bubbles from the shaking. This composition will serve as the base primer formula and will be referred to as Primer A.

[0069] Other primer compositions were made as detailed in the following tables.

[0070] Table 3. Composition of primer solution (wt.% solids of cured primer)

[0071] Table 4. Composition of primer solution (wt.% solids of cured primer)

[0072] Applying primer coat to polymer substrates using spin coater

[0073] A Laurell Technologies Corp model WS-400-B8NPP / Lite / AS spin coater was used to coat the primer solution onto the polymer substrate samples. A sample was mounted to a 2-inch round vacuum chuck. The spin coater was then programmed to spin at a rate of 4,000 RPM for 2 minutes with an acceleration setting of 1032. Using a pipette, the primer solution was flood coated over the entire sample. The lid was closed and then the spin coater started. When the spin coating process was complete, the substrate was transferred to an aluminum pan and placed in an oven to dry at 80 °C for 3 minutes. The samples were then cured on a Heraeus fusion processor using an H-bulb with 2-passes at 25 ft / min and 100% power. The total exposure for each sample was 1230 mJ / cm2UVA, 948 mJ / cm2UVB, 231.0 mJ / cm2UVC, and 1462 mJ / cm2UW.

[0074] (PDAC / PSS) Solution preparation for Laver-bv-Laver Deposition

[0075] In a 1.75”x4.75”x5.5” rectangular vessel, 2.24 grams of PDAC and 117 grams of NaC125 are mixed into 385 grams of deionized water forming a uniform 0.2 wt.% PDAC solution. In another 1.75”x4.75”x5.5” rectangular vessel, 3.35 grams of PSS and 117 grams of NaC125 are mixed into 384 grams of deionized water forming a uniform 0.2 wt.% PSS solution. In another 1.75”x4.75”x5.5” rectangular vessel, 0.5 grams of acid blue dye were mixed into 500 grams of deionized water forming a 0.1 wt.% dye solution.

[0076] All the polymer substrate surfaces prepared for layer-by-layer deposition were treated with 5 passes of an Electro-Technic Products model BD-20AC handheld corona treater (Chicago, IL, USA). Thus, corona treated substrates were compared to the same substrate with both corona treatment and primer.

[0077] The layer-by-layer deposition process was carried out by first exposing the sample to the cation (PD AC) solution via immersion and removing it immediately, then rinsing the sample with deionized water and blowing it dry with house compressed air. The sample is then subjected to the same procedure with the anion (PSS) solution, also followed by rinsing the sample with deionized water and blowing it dry with house compressed air. This sequential exposure of the sample to cation and anion solutions forms a deposited bilayer, and this process was repeated until 10 bilayers were deposited.

[0078] When the 10 bilayers were complete, the sample once more was exposed to the cation (PDAC) solution with similar rinsing and drying. The sample was then exposed to the acid blue dye solution for 1 minute followed by similar rinsing and drying. The blue dye is present in order to visually determine whether the layer-by-layer coating is damaged from the tape.

[0079] Tape Test for Visually Quantifying Adhesion of Laver-bv-Laver Coating to Substrate

[0080] A 1” wide strip of 3M Company 232 masking tape (St. Paul, MN) is laminated over the coated portion of the sample with a small overhanging tab. A rubber roller is then passed over the sample, back and forth, five times while applying pressure to ensure the masking tape is well laminated to the sample. A black permanent marker was used to mark the edges of the sample to indicate the area being tested. Next, the masking tape is slowly peeled back at a 90° angle starting with the overhanging tab.

[0081] This process was repeated a second time in the same marked testing area to further try to remove any poorly adhered coating. After the second tape test was performed, the sample was imaged and evaluated for how much area of the coating was affected by being either scratched, worn, or completely removed. This evaluation was quantitated by applying a grid over the tested area in the image. Any spot where the coating was affected, as defined previously, a red square was indicated. A white square was used to indicate that there was not enough sample / substrate to fill in half of that square’s area . The % surface area affected by the tape was calculated by dividing the number of red squares by the (total number of squares in the grid minus the number of white squares). The following Tables 5 and 6 list the substrates, primers, and test results.

[0082] Table 5 Table 6

[0083] (PAH / PAA) Solution preparation

[0084] In a 1.75”x4.75”x5.5” rectangular vessel, 3.33 grams of PAH was mixed into 497 grams of deionized water forming a uniform 0.1 wt.% PAH solution. Using a calibrated pH probe, HO was added in dropwise until the PAH solution pH=7.5. In another 1.75”x4.75”x5.5” rectangular vessel, 4.00 grams of PAA was mixed into 496 grams of deionized water forming a uniform 0.2 wt.% PAA solution. Using a calibrated pH probe, NaOH was added in dropwise until the PAA solution pH=3.5. In another 1.75”x4.75”x5.5” rectangular vessel, 0.5 grams of acid blue dye were mixed into 500 grams of deionized water forming a 0.1 wt.% dye solution.

[0085] (PAH / PAA) deposition The same procedure described above for deposition of (PDAC / PSS) was also used for (PAH / PAA), however the number of bilayers was increased to 12. After the 12thbilayer was complete, the sample being coated was dipped again in PAH followed by rinsing and drying and then dipped in acid blue dye. The final LbL construction was (PAH / PAA) 125 / Acid blue dye. Table 7 list the samples that were prepared with the (PAH / PAA) coating. Table 7

[0086] Tape test evaluation

[0087] The tape test was performed the same way as described above, however the evaluation of the samples was difficult because the dye did not stain the coating as strongly as with (PDAC / PSS). Instead, a BYK (Wesel, Germany) haze-gard i instrument was used to measure the transmission of the coatings before and after the tape test. Example 20 had a transmission of 92% before and after the tape test, indicated that the coating was unaffected by the tape test. Example 21 had a transmission of about 91.5% before the tape test, but 93.3 after the tape test indicating the sample did not preform as well as Example 20.

Claims

What is claimed is:

1. A method of making an article comprising: providing a substrate; applying a primer layer to the substrate; wherein the primer layer comprises the reaction product of a polymerizable resin comprising at least one monomer with at least two ethylenically unsaturated groups; and applying a plurality of layers deposited by layer-by-layer self-assembly to the primer layer.

2. The method of claim 1 wherein the polymerizable resin is cured by exposure to actinic radiation.

3. The method of claims 2 wherein the polymerizable resin is cured before applying the plurality of layers, after applying the plurality of layers, or a combination thereof.

4. The method of claims 1-3 wherein the plurality of layers comprise at least one poly cationic polymer and at least one polyanionic polymer.

5. The method of claims 1-4 wherein the substrate is inorganic material, organic polymeric material, or combination thereof.

6. The method of claims 1-5 wherein the substrate comprises an organic polymer is selected from the group consisting of polyolefins, polyester, and acrylic.

7. The method of claim 6 wherein the organic polymers comprise cycloaliphatic or aromatic moieties.

8. The method of claims 1-7 wherein the primer layer has a thickness less than 1 micron, 750 nm, 500 nm, or 250 nm.

9. The method of claims 1-8 wherein the polymerizable resin comprises at least one non-aromatic monomer with at least two (meth)acrylate groups.

10. The method of claims 1-9 wherein the polymerizable resin comprises at least one monomer with at least three (meth)acrylate groups.

11. The method of claims 1-10 wherein the polymerizable resin further comprises at least one polar monomer including acidic and (meth)acrylamide monomers.

12. The method of claims 1-11 wherein the polymerizable resin further comprises at least one mono(meth)acrylate monomer.

13. An article comprising: a substrate; a primer layer disposed on the substrate; wherein the primer layer comprises the reaction product of a polymerizable resin comprising at least one monomer with at least two ethylenically unsaturated groups; and a plurality of layers deposited by layer-by-layer self-assembly disposed on the primer layer.

14. An article comprising: a substrate; a primer layer disposed on the substrate; wherein the primer layer comprises the reaction product of a polymerizable resin comprising at least one monomer with at least two ethylenically unsaturated groups; and an ionically bonded polymer matrix disposed on the substrate.

15. The article of claim 14 wherein the ionically bonded polymer matrix comprises at least two different organic polymers.

16. The article of claim 14-15 wherein the polymeric matrix is crosslinked.

17. The article of claims 14-16 further characterized by claims 2-12.

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