ENCAPSULATION BARRIER STACK

Abstract

Disclosed is an encapsulation barrier stack, capable of encapsulating a moisture and/or oxygen sensitive article and comprising a multilayer film, wherein the multilayer film comprises: one or more barrier layer(s) having low moisture and/or oxygen permeability, and one or more sealing layer(s) arranged to be in contact with a surface of the at least one barrier layer, thereby covering defects present in the barrier layer,
wherein the one or more sealing layer(s) comprise(s) a plurality of encapsulated nanoparticles, the nanoparticles being reactive in that they are capable of interacting with moisture and/or oxygen to retard the permeation of moisture and/or oxygen through the defects present in the barrier layer. The encapsulation of the particles can be obtained by polymerising a polymerisable compound (a monomeric or a polymeric compound with polymerisible groups or) cross-linking a cross-linkable compound on the surface of the reactive nanoparticles.

Claims

1. A method of manufacturing an encapsulation barrier stack, said encapsulation barrier stack comprising: a multilayer film, wherein the multilayer film is capable of encapsulating a moisture and/or oxygen sensitive article and wherein the multilayer film comprises: one or more barrier layer(s) having low moisture and/or oxygen permeability, and one or more sealing layer(s) arranged to be in contact with a surface of at least one of the one or more barrier layer(s), thereby covering and/or plugging defects present in the one or more barrier layer(s), wherein the one or more sealing layer(s) comprise(s) a plurality of encapsulated nanoparticles, the encapsulated nanoparticles being capable of interacting by way of chemical reaction with the moisture and/or the oxygen thereby retarding the permeation of the moisture and/or the oxygen; said method comprising: providing one or more barrier layer(s), and forming one or more sealing layer(s), wherein forming the one or more sealing layer(s) comprises: (i) mixing a polymerizable compound or a cross-linkable compound with a plurality of nanoparticles, the nanoparticles being capable of interacting by way of chemical reaction with moisture and/or oxygen, thereby forming a sealing mixture, and (ii) applying the sealing mixture onto the one or more barrier layer(s) and polymerizing the polymerizable compound or to cross-link the cross-linkable compound to form a polymer under conditions allowing the nanoparticles to be encapsulated by the formed polymer.

2. The method of claim 1, further comprising adding a surfactant to the sealing mixture.

3. The method of claim 1, further comprising adding a surface modifying compound to the sealing mixture.

4. The method of claim 1, wherein providing the one or more barrier layer(s) comprises forming the one or more barrier layer(s).

5. The method of claim 1, wherein the conditions and/or the concentration of the polymerizable compound is chosen such that the polymerizable compound is immobilized on the surface of the nanoparticles.

6. The method of claim 1 wherein the sealing mixture is applied onto the barrier layer via conformal deposition.

7. The method of claim 6, wherein the sealing mixture is applied onto the one or more barrier layer(s) by means of spin coating, screen printing, a WebFlight method, slot die, curtain gravure, knife coating, ink jet printing, screen printing, dip coating, plasma polymerization or a chemical vapour deposition (CVD) method.

8. The method of claim 1, wherein after being deposited onto the one or more barrier layer(s) the sealing mixture is exposed to conditions that initiate polymerization of the polymerizable compound or cross-linking the cross-linkable compound.

9. The method of claim 1, wherein the one or more sealing layer(s) formed at least essentially consist(s) of the polymer encapsulated reactive nanoparticles.

10. The method of claim 1, further comprising carrying out sonification of the sealing mixture prior to polymerization.

11. The method of claim 1, the method further comprising providing a substrate for supporting the encapsulation barrier stack.

12. The method of claim 1, wherein the plurality of nanoparticles is a colloidal dispersion comprising nanoparticles dispersed in an organic solvent.

13. The method of claim 1, wherein the mixing of the polymerizable compound with the plurality of nanoparticles is carried out in a polar organic solvent.

14. The method of claim 13, wherein the polar organic solvent comprises a mixture of isopropanol and ethyl acetate in 1:3 molar ratio.

15. The method of claim 1, wherein the polymerizable or cross-linkable compound is curable by ultraviolet light, infrared light, electron beam curing, plasma polymerisation and or heat curing.

16. The method of claim 15, wherein the polymerizable compound is selected from acrylic acid, methyl acrylate, ethyl acrylate and butyl acrylate or wherein the cross-linkable compound is an oligomer or a polymer.

17. The method of claim 1 wherein the mixing of the polymerizable or cross-linkable compound with the plurality of nanoparticles in step (i) comprises mixing about 20 wt.-% dry form or less of the monomer to 80 wt.-% dry form of the nanoparticles (weight ratio 1:4 or less).

18. The method of claim 17, wherein the polymerizable or cross-linkable compound is mixed with the nanoparticle at a weight ratio of 1:5 or less.

19. The method of claim 1, wherein the sealing mixture obtained in step (i) comprises 10% (w/v) or less of the polymerizable or cross-linkable compound.

20. The method of claim 19, wherein the sealing mixture comprises about 5% (w/v) of the polymerizable or cross-linkable compound.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] FIG. 1 depicts a known barrier stack device, in which the barrier oxide coating defects are decoupled by an intermediate polymer layer. The tortuous path, i.e. the permeation path for fluid or the time taken to diffuse through the barrier depends on the number of inorganic/organic pairs used. If a higher number of the pairs are used, the path is longer and therefore, higher barrier properties can be achieved. Using multiple barrier layers, the overall performance will vary depending on whether the pinholes in one barrier layer are lined up with the defects in the other barrier layers or not. In addition, if the numbers of defects are higher, the decoupling concept will not work. In the sense, the defects of the barrier layer may be lined up with the defects in the second barrier layer. This invention requires very high packing density (lower number of pin holes) barrier oxide films, which are produced either by sputtering methods or PECVD methods.

[0075] FIG. 2 depicts a further known barrier stack device disclosed in WO 2008/057045 and WO2010/140980, in which nanoparticles are distributed in the polymer matrix to improve the barrier properties. These disclosures are not concerned with sealing barrier oxide film defects. A drawback of the device shown in FIG. 2 is that water vapor will be released through the pinholes of the barrier oxide films once the reactive nanoparticles are saturated with water vapor. Further, there is a limitation in loading the nanoparticles in the thermoplastics (the base film normally formed by extrusion process where in the thermoplastic melts, the films are drawn and then cooled down), it is a complex process and a higher number of getter nanoparticles loading in the film would affect the transmittance.

[0076] FIG. 3A depicts an embodiment of a barrier stack according to the invention. FIG. 3B depicts a further embodiment of a barrier stack according to the invention. FIG. 3C depicts yet another embodiment of a barrier stack according to the invention, deposited onto a planarized or non-planarized substrate that is of plastic material.

[0077] FIG. 4 illustrates a qualitative test on barrier stack performance, analysing whether calcium degradation can occur (Type A).

[0078] FIG. 5 illustrates a quantitative test on barrier stack performance, analysing calcium degradation (Type B).

[0079] FIG. 6 depicts a nanogetter layer coated polycarbonate substrate.

[0080] FIG. 7 shows an SEM picture depicting the surface topography of polymer encapsulated nanoparticles at 20.000? magnification.

[0081] FIG. 8 shows an SEM picture depicting the surface topography of polymer encapsulated nanoparticles at 45.000? magnification.

[0082] FIG. 9 shows an SEM picture of plain Anodisc? with 200 nm pinholes before coating at 10,000? magnification.

[0083] FIG. 10 shows an SEM picture of encapsulated nanoparticles coated (4 micron coating thickness) onto the Anodise? (as shown in FIG. 9) in cross section at 13,000? magnification.

[0084] FIG. 11 depicts an SEM picture of the bottom side of Anodise?, which was coated with a layer of polymer encapsulated nanoparticles shown at a magnification of 10,000. The disk was peeled off from the plastic substrate, thus showing the defects sealing mechanism.

[0085] FIG. 12 shows a TEM image illustrating that the nanoparticles are distributed in the polymer layer/film (50 nm scale).

[0086] FIG. 13A shows a SEM image of the distribution of aluminum oxide nanoparticles in a polymer matrix as known in the art at 35.000? magnification. FIG. 13B shows a SEM image of prior art aluminium oxide nanoparticles before encapsulation at 70.000? magnification. FIG. 13C shows a SEM image of the polymer encapsulated nanoparticles of the invention at 100.000? magnification and FIG. 13D shown a SEM image of a layer of polymer encapsulated nanoparticles.

[0087] FIG. 14A and FIG. 14B depict the results of a standard test method for peel resistance. The ASTM peel test optical images show no delamination of the polymer encapsulated nanoparticle layeraluminium oxideinterfaces.

[0088] FIG. 15 shows an illustration of polymer encapsulated nanoparticles and with polymer passivated particles as used in the invention, with FIGS. 15A and 15B showing a partially encapsulated (i.e. a passivated) nanoparticle and FIG. 15C showing a completely encapsulated nanoparticle.

[0089] FIG. 16A and FIG. 16B show SEM images of a cross section of a barrier stack of the invention at 50.000? magnification having a sealing layer of polymer encapsulated nanoparticles, deposited on an oxide layer which in turn is arranged on a PET plastic substrate. FIG. 16A shows the layer 1 and the layer 2, however not the layer of the nanoparticles distributed in the polymer matrix nor the upper Al.sub.2O.sub.3 layer. The layer of the nanoparticles distributed in the polymer matrix and the upper Al.sub.2O.sub.3 layer are shown in FIG. 16B.

[0090] FIG. 17 shows a SEM image of a cross section of a barrier stack of the invention at 30.000? magnification having a sealing layer of polymer encapsulated nanoparticles, deposited on an oxide layer which in turn is arranged on a PET plastic substrate.

DETAILED DESCRIPTION OF THE INVENTION

[0091] FIG. 3C shows one embodiment of an encapsulation barrier stack according to the invention, which is in addition arranged on a plastic substrate. The encapsulation barrier stack comprises a multilayer film. The multilayer film comprises one or more barrier layers and one or more sealing layers. The multilayer film may for example include one, two, three, four, five, six, seven, eight nine or ten barrier layers. The multilayer film may for example include one, two, three, four, five, six, seven, eight nine or ten sealing layers. In embodiments with a plurality of barrier layers and sealing layers individual barrier layers and sealing layers may be in contact with other barrier layers and/or sealing layers. In some embodiments an individual barrier layer is in contact with two further barrier layers. In some embodiments an individual barrier layer is in contact with two sealing layers. In some embodiments an individual barrier layer is in contact with one further barrier layer and one sealing layer. In some embodiments an individual sealing layer is in contact with two further sealing layers. In some embodiments an individual sealing layer is in contact with two barrier layers. In some embodiments an individual sealing layer is in contact with one further sealing layer and one barrier layer. In some embodiments two or more sealing layers and one or more barrier layer(s) of the multilayer film are arranged in an alternating manner. In some embodiments the multilayer film includes a plurality of sealing layers and barrier layers arranged in an alternating sequence. In the embodiment depicted in FIG. 3C one barrier layer is present, denominated the barrier oxide. In the embodiment depicted in FIG. 3C two sealing layers are present, each denominated a functional nano layer. As noted above, it is also the scope of the present invention that each barrier layer has a different number of sealing layers arranged thereon. In it also in the scope of the invention that in case of a barrier stack with more than one sealing layers, only the sealing layer that directly contacts the barrier layer comprises or consists of polymer encapsulated nanoparticles of the invention and that other layers can be a sealing layer of the prior art, for example, a sealing layer as described in WO 2008/057045 in which reactive nanoparticles are distributed in a polymer matrix. The barrier layers have low permeability to oxygen and/or moisture. It will be noted that barrier layers contain pinhole defects which extend through the thickness of the barrier layer. Pinhole defects along with other types of structural defects limit the barrier performance of barrier layers as oxygen and water vapour can permeate into the barrier layer via these defects, eventually traversing the encapsulation barrier stack and coming into contact with the oxygen/moisture sensitive device.

[0092] The sealing layer(s) comprise(s) reactive nanoparticles capable of interacting with water vapour and/or oxygen, thereby retarding the permeation of oxygen/moisture through the encapsulation barrier stack. In accordance with the present invention, these defects are at least partially covered up, or in some embodiments, entirely filled up by the nanoparticles in the sealing layer. The nanoparticles are polymer encapsulated. Examples of suitable polymers include, but are not limited to, polypropylene, polyisoprene, polystyrene, polyvinyl chloride, polyisobutylene, polyethylene terephthalate (PET), polyacrylates (e.g. polymethyl-methacrylate (PMMA)), ethylene-vinyl acetate (EVA) copolymers, phenol formaldehyde resins, epoxy resins, poly(N-propargylamides), poly(O-propargylesters), and polysiloxanes.

[0093] The monomer or the pre-polymer that is used for the encapsulation of the reactive nanoparticles (and that is typically included in a non-aqueous based discontinuous phase solution for the preparation of the sealing layer) may be selected from any suitable hydrophobic material. Illustrative examples of hydrophobic monomers include, but are not limited to, styrenes (e.g., styrene, methylstyrene, vinylstyrene, dimethylstyrene, chlorostryene, dichlorostyrene, tert-butylstyrene, bromostyrene, and p-chloromethylstyrene), monofunctional acrylic esters (e.g., methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, butoxyethyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, octyl acrylate, decyl acrylate, dodecyl acrylate, octadecyl acrylate, benzyl acrylate, phenyl acrylate, phenoxyethyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, isoamyl acrylate, lauryl acrylate, stearyl acrylate, benhenyl acrylate, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, methoxydipropylene glycol acrylate, phenoxypolyethylene glycol acrylate, nonylphenol EO adduct acrylate, isooctyl acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl diglycol acrylate, and oxtoxypolyethylene glycol polypropylene glycol monoacrylate), monofunctional methacrylic esters (e.g., methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, isodecyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, methoxydiethylene glycol methacrylate, polypropylene glycol monomethacrylate, benzyl methacrylate, phenyl methacrylate, phenoxyethyl methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, tert-butylcyclohexyl methacrylate, behenyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyloxyethyl methacrylate, and polypropylene glycol monomethacrylate), allyl compounds (e.g., allylbenzene, allyl-3-cyclohexane propionate, 1-allyl-3,4-dimethoxybenzene, allyl phenoxyacetate, allyl phenylacetate, allylcyclohexane, and allyl polyvalent carboxylate), unsaturated esters of fumaric acid, maleic acid, itaconic acid, etc., and radical polymerizable group-containing monomers (e.g., N-substitued maleimide and cyclic olefins).

[0094] In one embodiment, the polymer-encapsulated nanoparticles may be formed in a non-water-based solution (sealing mixture). In this embodiment, the monomers may be selected from acid containing radical polymerizable monomers.

[0095] In another embodiment, the polymer-encapsulated nanoparticles may be formed in the sealing mixture of an acid containing radical polymerizable monomers. In this embodiment, the monomer may be selected from acrylic acid, methacrylic acid, acrylamides, methacrylamides, hydroxyethyl-methacrylates, ethylene-oxide-base methacrylates, and combinations thereof.

[0096] In another embodiment, the polymer-encapsulated nanoparticle may be formed in a sealing mixture wherein pre-polymers are used. Such pre-polymers might be selected from an acrylic oligomer having a molecular weight less than about 1000 Da and a viscosity less than about 300 cPoise.

[0097] In some embodiments the one or more sealing layer(s) at least essentially consist(s) of the polymer encapsulated reactive nanoparticles. The term at least essentially consisting of means that the respective layer is generally free of other matter, as judged by standard analytical techniques. The layer may contain minor amounts of other matter, but it may also be entirely free of other matter, at least as judged by known analytical techniques. Thus, the one or more sealing layer(s) may consist(s) only of the polymer encapsulated reactive nanoparticles. A portion of the plurality of polymer encapsulated nanoparticles or all polymer encapsulated nanoparticles may have an aliphatic, alicyclic, aromatic or arylaliphatic compound immobilized thereon. The aliphatic, alicyclic, aromatic or arylaliphatic compounds have a polar group. The polar group may, for example, be a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, an amido group, a thio group, a seleno group, and a telluro group.

[0098] The term aliphatic means, unless otherwise stated, a straight or branched hydrocarbon chain, which may be saturated or mono- or poly-unsaturated and include heteroatoms (see below). An unsaturated aliphatic group contains one or more double and/or triple bonds (alkenyl or alkinyl moieties). The branches of the hydrocarbon chain may include linear chains as well as non-aromatic cyclic elements. The hydrocarbon chain, which may, unless otherwise stated, be of any length, and contain any number of branches. Typically, the hydrocarbon (main) chain includes 1 to 5, to 10, to 15 or to 20 carbon atoms. Examples of alkenyl radicals are straight-chain or branched hydrocarbon radicals which contain one or more double bonds. Alkenyl radicals normally contain about two to about twenty carbon atoms and one or more, for instance two, double bonds, such as about two to about ten carbon atoms, and one double bond. Alkynyl radicals normally contain about two to about twenty carbon atoms and one or more, for example two, triple bonds, such as two to ten carbon atoms, and one triple bond. Examples of alkynyl radicals are straight-chain or branched hydrocarbon radicals which contain one or more triple bonds. Examples of alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, the n isomers of these radicals, isopropyl, isobutyl, isopentyl, sec-butyl, tert-butyl, neopentyl, 3,3-dimethylbutyl. Both the main chain as well as the branches may furthermore contain heteroatoms as for instance N, O, S, Se or Si or carbon atoms may be replaced by these heteroatoms.

[0099] The term alicyclic means, unless otherwise stated, a non-aromatic cyclic moiety (e.g. hydrocarbon moiety), which may be saturated or mono- or poly-unsaturated. The cyclic hydrocarbon moiety may also include fused cyclic ring systems such as decalin and may also be substituted with non-aromatic cyclic as well as chain elements. The main chain of the cyclic hydrocarbon moiety may, unless otherwise stated, be of any length and contain any number of non-aromatic cyclic and chain elements. Typically, the hydrocarbon (main) chain includes 3, 4, 5, 6, 7 or 8 main chain atoms in one cycle. Examples of such moieties include, but are not limited to, cylcopentyl, cyclohexyl, cycloheptyl, or cyclooctyl. Both the cyclic hydrocarbon moiety and, if present, any cyclic and chain substituents may furthermore contain heteroatoms, as for instance N, O, S, Se or Si, or a carbon atom may be replaced by these heteroatoms. The term alicyclic also includes cycloalkenyl moieties that are unsaturated cyclic hydrocarbons, which generally contain about three to about eight ring carbon atoms, for example five or six ring carbon atoms. Cycloalkenyl radicals typically have a double bond in the respective ring system. Cycloalkenyl radicals may in turn be substituted.

[0100] The term aromatic means, unless otherwise stated, a planar cyclic hydrocarbon moiety of conjugated double bonds, which may be a single ring or include multiple fused or covalently linked rings, for example, 2, 3 or 4 fused rings. The term aromatic also includes alkylaryl. Typically, the hydrocarbon (main) chain includes 5, 6, 7 or 8 main chain atoms in one cycle. Examples of such moieties include, but are not limited to, cylcopentadienyl, phenyl, napthalenyl-, [10]annulenyl-(1,3,5,7,9-cyclodecapentaenyl-), [12]annulenyl-, [8]annulenyl-, phenalene (perinaphthene), 1,9-dihydropyrene, chrysene (1,2-benzophenanthrene). An example of an alkylaryl moiety is benzyl. The main chain of the cyclic hydrocarbon moiety may, unless otherwise stated, be of any length and contain any number of heteroatoms, as for instance N, O and S. Examples of such heteroarom containing moieties (which are known to the person skilled in the art) include, but are not limited to, furanyl-, thiophenyl-, naphtyl-, naphthofuranyl-, anthraxthiophenyl-, pyridinyl-, pyrrolyl-, quinolinyl, naphthoquinolinyl-, quinoxalinyl-, indolyl-, benzindolyl-, imidazolyl-, oxazolyl-, oxoninyl-, oxepinyl-, benzoxepinyl-, azepinyl-, thiepinyl-, selenepinyl-, thioninyl-, azecinyl-(azacyclodecapentaenyl-), diazecinyl-, azacyclododeca-1,3,5,7,9,11-hexaene-5,9-diyl-, azozinyl-, diazocinyl-, benzazocinyl-, azecinyl-, azaundecinyl-, thia[11]annulenyl-, oxacyclotrideca-2,4,6,8,10,12-hexaenyl- or triazaanthracenyl-moieties.

[0101] By the term arylaliphatic is meant a hydrocarbon moiety, in which one or more aromatic moieties are substituted with one or more aliphatic groups. Thus the term arylaliphatic also includes hydrocarbon moieties, in which two or more aryl groups are connected via one or more aliphatic chain or chains of any length, for instance a methylene group. Typically, the hydrocarbon (main) chain includes 5, 6, 7 or 8 main chain atoms in each ring of the aromatic moiety. Examples of arylaliphatic moieties include, but are not limited, to 1-ethyl-naphthalene, 1,1-methylenebis-benzene, 9-isopropylanthraxcene, 1,2,3-trimethyl-benzene, 4-phenyl-2-buten-1-ol, 7-chloro-3-(1-methylethyl)-quinoline, 3-heptyl-furan, 6-[2-(2,5-diethylphenyl)ethyl]-4-ethyl-quinazoline or, 7,8-dibutyl-5,6-diethyl-isoquinoline.

[0102] Each of the terms aliphatic, alicyclic, aromatic and arylaliphatic as used herein is meant to include both substituted and unsubstituted forms of the respective moiety. Substituents my be any functional group, as for example, but not limited to, amino, amido, azido, carbonyl, carboxyl, cyano, isocyano, dithiane, halogen, hydroxyl, nitro, organometal, organoboron, seleno, silyl, silano, sulfonyl, thio, thiocyano, trifluoromethyl sulfonyl, p-toluenesulfonyl, bromobenzenesulfonyl, nitrobenzenesulfonyl, and methane-sulfonyl.

[0103] In some embodiments the at least one sealing layer conforms substantially to the shape of the defects present on the surface of the at least one barrier layer. The sealing layer may act as a planarising material that smoothens the surface of the substrate, thereby covering defects on the substrate which could provide pathways for the infiltration of moisture/oxygen. In this regard, application of a sealing layer above a barrier layer may further allow smoothening the surface in case further barrier layers are intended to be deposited on the barrier film.

[0104] The preceding embodiments relate to an encapsulation barrier stack in which the multilayer film is immobilized, e.g. laminated onto only one side of a substrate. In some embodiments a barrier stack is immobilized on a double-laminated substrate in which a multilayer film is laminated or deposited on to two sides, which may be opposing sides, of a base substrate. An encapsulation barrier stack may for instance include a substrate that is sandwiched between two multilayer films.

[0105] As will be apparent from the above, a multilayer film according to the invention has at least two layers, a barrier layer and a sealing layer, each of which has an upper face and a lower face, defining a plane. Each layer further has a circumferential wall defining a thickness of the layer. Typically each layer is of at least essentially uniform thickness. In some embodiments the circumference of each layer is of at least essentially the same dimensions as the circumference of any other layer. A multilayer film according to the invention has two (upper and lower) outer surfaces defined by the upper face of a first layer and the lower face of a second layer. These two surfaces are arranged on at least essentially opposing sides of the multilayer film. Each of these two surfaces defines a plane. In typical embodiments these two planes are essentially parallel to each other. Furthermore these two surfaces are exposed to the ambience. Typically one or both of these planes is/are adapted for being contacted with the surface of a substrate, including for being immobilized thereon. In some embodiments the surface topology of the respective surface of the multilayer film is at least essentially matching, e.g. at least essentially congruent to, the surface topology of the plane of the substrate.

[0106] The encapsulation barrier stack of the invention can be used in several ways for encapsulating a moisture and oxygen sensitive device. Any device may be encapsulated by an encapsulation barrier stack of the invention, such as an OLED, pharmaceutical drugs, jewellery, reactive metals, electronic components or food substances. For example, it can be arranged, for example laminated or deposited, onto a conventional polymer substrate that is used to support the OLED. As explained above, pinhole defects in the barrier layer are sealed by the polymer encapsulated nanoparticulate material of the sealing layer. The OLED may be arranged directly on the multilayer film, and for instance encapsulated under a cover such as a glass cover, for instance using rim sealing or thin-film encapsulation comprising the attachment of an encapsulation barrier stack over the OLED, hereinafter referred to as proximal encapsulation, is also possible. Proximal encapsulation is in particular suitable for flexible OLED devices. In such an embodiment the multilayer film of the encapsulation barrier stack conforms to the external shape of the OLED device.

[0107] An encapsulation barrier stack according to the invention may be produced by forming on one or more barrier layer(s), on a substrate or on a (further) sealing layer, a sealing layer. In some embodiments the sealing layer may be formed on a substrate. The sealing layer may be formed by mixing a polymerisable compound with a plurality of reactive nanoparticles as defined above. The plurality of nanoparticles may in some embodiments be a colloidal dispersion comprising nanoparticles dispersed in a suitable liquid such as an organic solvent. In some embodiments a polar solvent such as e.g. ethanol, acetone, N,N-dimethyl-formamide, isopropanol, ethyl acetate or nitromethane, or a non-polar organic solvent such as e.g. benzene, hexane, dioxane, tetrahydrofuran or diethyl ether (cf. also below). As explained above, in order to allow for encapsulation of the reactive nanoparticles, the polymerisable compound (which might be a monomeric compound) is present in such a low concentration in the sealing mixture that the polymerisable compound is adsorbed on the surface of the reactive particles, thereby coating the particles and avoiding formation of a (bulk) matrix that incorporates the entire reactive particles.

[0108] Often liquids are classified into polar and non-polar liquids in order to characterize properties such as solubility and miscibility with other liquids. Polar liquids typically contain molecules with an uneven distribution of electron density. The same classification may be applied to gases. The polarity of a molecule is reflected by its dielectric constant or its dipole moment. Polar molecules are typically further classified into protic and non-protic (or aprotic) molecules. A fluid, e.g. a liquid, that contains to a large extent polar protic molecules may therefore be termed a polar protic fluid. A fluid, e.g. a liquid, that contains to a large extent polar non-protic molecules may be termed a polar non-protic fluid. Protic molecules contain a hydrogen atom which may be an acidic hydrogen when the molecule is dissolved for instance in water or an alcohol. Aprotic molecules do not contain such hydrogen atoms.

[0109] Examples of non-polar liquids include, but are not limited to, hexane, heptane, cyclohexane, benzene, toluene, dichloromethane, carbon tetrachloride, carbon disulfide, dioxane, diethyl ether, or diisopropylether. Examples of dipolar aprotic liquids are methyl ethyl ketone, chloroform, tetrahydrofuran, ethylene glycol monobutyl ether, pyridine, methyl isobutyl ketone, acetone, cyclohexanone, ethyl acetate, isobutyl isobutyrate, ethylene glycol diacetate, dimethylformamide, acetonitrile, N,N-dimethyl acetamide, nitromethane, acetonitrile, N-methylpyrrolidone, methanol, ethanol, propanol, isopropanol, butanol, N,N-diisopropylethylamine, and dimethylsulfoxide. Examples of polar protic liquids are water, methanol, isopropanol, tert.-butyl alcohol, formic acid, hydrochloric acid, sulfuric acid, acetic acid, trifluoroacetic acid, dimethylarsinic acid [(CH.sub.3).sub.2AsO(OH)], acetonitrile, phenol or chlorophenol. Ionic liquids typically have an organic cation and an anion that may be either organic or inorganic. The polarity of ionic liquids (cf. below for examples) is known to be largely determined by the associated anion. While e.g. halides, pseudohalides, BF.sub.4.sup.?, methyl sulphate, NO.sub.3.sup.?, or ClO.sub.4.sup.? are polar liquids, hexafluorophosphates, AsF.sub.6.sup.?, bis(perfluoroalkyl)-imides, and [C.sub.4F.sub.6SO.sub.3].sup.? are non-polar liquids.

[0110] The mixing of the polymerisable compound with the plurality of nanoparticles may in some embodiments be carried out in a polar organic solvent such as defined above. In one embodiment the polar organic solvent includes a mixture of isopropanol and ethyl acetate, for example in a molar ratio from about 2:1 to about 1:10, e.g. about 1:1, about 1:2, about 1:3, about 1:5 or about 1:10. The mixture of the polymerisable compound and the reactive nanoparticles may be applied onto the barrier layer, and the polymerisable compound may be polymerised to form a polymer. Polymerisation is allowed to occur under conditions that allow the nanoparticles to be encapsulated by the polymer formed, i.e. using a low concentration of the polymerisable compound and, for example, additionally subjecting the sealing mixture to sonification. The sealing solution may be web flight coated onto the barrier layer, for example, via a roll-to-roll process. The coating of barrier layer and sealing layer is repeated for a predetermined number of times to obtain a multilayer film with a desired barrier property. For example, a multilayer film comprising 5 paired layers may be obtained by oxide coating and web flight coating to be repeated 5 times to form 5 paired layer.

[0111] In some embodiments a surfactant is added to the mixture of the polymerisable compound and the plurality of nanoparticles. Numerous surfactants, which are partly hydrophilic and partly lipophilic, are used in the art, such as for instance alkyl benzene sulfonates, alkyl phenoxy polyethoxy ethanols, alkyl glucosides, secondary and tertiary amines such as diethanolamine, Tween, Triton 100 and triethanolamine, or e.g. fluorosurfactants such as ZONYL? FSO-100 (DuPont). A surfactant may for instance be a hydrocarbon compound, a hydroperfluoro carbon compound or a perfluorocarbon compound. It may for example be substituted by a sulfonic acid, a sulphonamide, a carboxylic acid, a carboxylic acid amide, a phosphate, or a hydroxyl group. Examples of a hydrocarbon based surfactant include, but are not limted to, sodium dodecyl sulfate, cetyl trimethyl-ammonium bromide, an alkylpolyethylene ether, dodecyldimethyl (3-sulfopropyl) ammonium hydroxide (C.sub.12N.sub.3SO.sub.3), hexadecyldimethyl (3-sulfopropyl) ammonium hydroxide (C.sub.16N.sub.3SO.sub.3), coco (amidopropyl)hydroxyl dimethylsulfo-betaine (RCONH(CH.sub.2).sub.3N.sup.+(CH.sub.3).sub.2CH.sub.2CH(OH)CH.sub.2SO.sub.3.sup.? with R?C.sub.8-C.sub.18), cholic acid, deoxy-cholic acid, octyl glucoside, dodecyl maltoside, sodium taurocholate, or a polymer surfactant such as e.g. Supelcoat PS2 (Supelco, Bellefonte, Pa., USA), methylcellulose, hydroxypropyl-cellulose, hydroxyethylcellulose, or hydroxypropylmethylcellulose. The surfactant may for instance be a hydrocarbon compound, a hydroperfluoro carbon compound or a perfluorocarbon compound (supra), which is substituted by a moiety selected from the group consisting of a sulfonic acid, a sulphonamide, a carboxylic acid, a carboxylic acid amide, a phosphate, or a hydroxyl group.

[0112] Examples of perfluorocarbon-surfactants include, but are not limited to, pentadecafluorooctanoic acid, heptadecafluorononanoic acid, tridecafluoroheptanoic acid, undecafluorohexanoic acid, 1,1,1,2,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heneicosafluoro-3-oxo-2-undecanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,6-tridecafluoro-1-hexanesulfonic acid, 2,2,3,3,4,4,5,5-octafluoro-5-[(tridecafluorohexyl)oxy]-pentanoic acid, 2,2,3,3-tetrafluoro-3-[(tri-decafluorohexyl)oxy]-propanoic acid], N,N-[phosphinicobis(oxy-2,1-ethanediyl)]bis[1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluoro-N-propyl-1-octanesulfonamide, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluoro-1-octanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluoro-1-octanesulfonyl fluoride, 2-[(?-D-galactopyra-nosyloxy)methyl]-2-[(1-oxo-2-propenyl)amino]-1,3-propanediyl carbamic acid (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-ester, 6-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl hydrogen phosphate)-D-glucose, 3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl hydrogen phosphate)-D-glucose, 2-(perfluorohexyl)ethyl isocyanate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-N-phenyl-octanamide, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-pentacosafluoro-N-(2-hydroxyethyl)-N-propyl-1-dodecanesulfonamide, 2-methyl-,2-[[(heptadecafluorooctyl)sulfonyl]methylamino]-2-propenoic acid ethyl ester, 3-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-1-oxooctyl)-benzenesulfonic acid, 3-(heptadecafluorooctyl)-benzenesulfonic acid, 4-[(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-1-oxooctyl)amino]-benzenesulfonic acid, 3-[(o-perfluorooctanoyl)-phenoxy]propanesulfonic acid, N-ethyl-1,1,2,2,2-pentafluoro-N-(26-hydroxy-3,6,9,12,15,18,21,24-octaoxahexacos-1-yl)-ethanesulfonamide, 3-[ethyl[(heptadecafluorooctyl)-sulfonyl]amino]-1-propanesulfonic acid, 1,2,2,3,3,4,5,5,6,6-decafluoro-4-(pentafluoroethyl)-cyclohexanesulfonic acid, 2-[1-[difluoro(pentafluoroethoxy)methyl]-1,2,2,2-tetrafluoroethoxy]-1,1,2,2-tetrafluoro-ethanesulfonic acid, N-[3-(dimethyloxidoamino)propyl]-2,2,3,3,4,4-hexafluoro-4-(heptafluoropropoxy)-butanamide, N-ethyl-N-[(heptadecafluorooctyl)sulfonyl]-glycine, or 2,3,3,3-tetrafluoro-2-[1,1,2,3,3,3-hexafluoro-2-[(tridecafluorohexyl)oxy]propoxy]-1-propanol, to name a few.

[0113] Examples of perfluorocarbon-surfactants also include polymeric compounds such as ?-[2-[bis(heptafluoropropyl)amino]-2-fluoro-1-(trifluoromethyl)ethenyl]-?-[[2-[bis(hepta-fluoropropyl)amino]-2-fluoro-1-(trifluoromethyl)ethenyl]oxy]-poly(oxy-1,2-ethanediyl), ?-[2-[[(nonacosafluorotetradecyl) sulfonyl]propylamino]ethyl]-?-hydroxy-poly(oxy-1,2-ethanediyl), polyethylene glycol diperfluorodecyl ether, ?-[2-[ethyl[(heptadecafluorooctyl)sulfonyl]amino]-ethyl]-?-hydroxy-poly(oxy-1,2-ethanediyl), ?-[2-[ethyl[(pentacosafluorododecyl)sulfonyl]-amino]ethyl]-?-hydroxy-poly(oxy-1,2-ethanediyl), ?-[2-[[(heptadecafluorooctyl)sulfonyl]-propylamino]ethyl]-??-hydroxy-poly(oxy-1,2-ethanediyl), N-(2,3-dihydroxypropyl)-2,2-difluoro-2-[1,1,2,2-tetrafluoro-2-[(tridecafluorohexyl)oxy]ethoxy]-acetamide, ?-(2-carboxy-ethyl)-?-[[(tridecafluorohexyl)oxy]methoxy]-poly(oxy-1,2-ethanediyl), ?-[2,3,3,3-tetrafluoro-2-[1,1,2,3,3,3-hexafluoro-2-(heptafluoropropoxy)propoxy]-1-oxopropyl]-?-hydroxy-poly(oxy-1,2-ethanediyl), and 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propionic acid polymer.

[0114] In some embodiments a surface modifying compound such as a silane is added to the sealing mixture. Examples of suitable silanes include acetoxy, alkyl, amino, amino/alkyl, aryl, diamino, epoxy, fluroalkyl, glycol, mercapto, methacryl, silicic acid ester, silyl, ureido, yinyl, and vinyl/alkyl silanes.

[0115] Illustrative examples of such silanes include, but are not limited to, di-tert-butoxydiacet-oxysilane, hexadecyltrimeth-oxysilane, alkylsiloxane, Bis(3-triethoxysilyl-propyl) amine, 3-aminopropyl-methyldiethoxysilane, triamino-functional propyltrimethoxy-silane, phenyltrimethoxysilane, phenyltriethoxysilane, 2-aminoethyl-3-amino-propylmethyl, dimethoxysilane, 2-aminoethyl-3-amino-propyl, trimethoxysilane, proprietary aminosilane composition, 3-glycidyloxy, propyltriethoxysilane, tridecafluoroocty-ltriethoxysilane, polyether-functional trimethoxysilane, 3-mercaptopropyltri-methoxysilane, 3-methacryloxypropyltrimethoxysilane, ethyl polysilicate, tetra-n-propyl orthosilicate, hexamethyl-disilazane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyl-functional oligosiloxane, 3-methacryloxypropyltrimethoxysilane and combinations thereof.

[0116] In some embodiments forming the sealing layer is carried out under an inert atmosphere, which may for example include or consist of nitrogen, argon, neon, helium, and/or sulfur hexafluoride (SF.sub.6).

[0117] Forming the one or more barrier layer(s) may be achieved by any suitable deposition method such as spin coating, flame hydrolysis deposition (FHD), slot die coating, curtain gravure coating, knife coating, dip coating, plasma polymerisation or a chemical vapour deposition (CVD) method. Examples of CVD methods include, but are not limited to plasma enhanced chemical vapor deposition (PECVD) or inductive coupled plasma enhanced chemical vapor deposition (ICP-CVD).

[0118] In one embodiment the barrier layer is deposited onto a further layer such as a sealing layer or onto a substrate using sputtering techniques known in the art. Sputtering is a physical process of depositing a thin film by controllably transferring atoms from a source to a substrate, which is known in the art. The substrate is placed in a vacuum chamber (reaction chamber) with the source material, named a target, and an inert working gas (such as argon) is introduced at low pressure. A gas plasma is struck in radio frequency (RF) or direct current (DC) glow (ejection of secondary electrons) discharged in the inter gas, which causes the gas to become ionized. The ions formed during this process are accelerated towards the surface of the target, causing atoms of the source material to break off from the target in vapour form and condense on the substrate. Besides RF and DC sputtering, magnetron sputtering is known as third sputtering technique. For magnetron sputtering, DC, pulsed DC, AC and RF power supplies can be used, depending upon target material, if reactive sputtering is desired and other factors. Plasma confinement on the target surface is achieved by locating a permanent magnet structure behind the target surface. The resulting magnetic field forms a closed-loop annular path acting as an electron trap that reshapes the trajectories of the secondary electrons ejected from target into a cycloidal path, greatly increasing the probability of ionization of the sputtering gas within the confinement zone. Positively charged argon ions from this plasma are accelerated toward the negatively biased target (cathode), resulting in material being sputtered from the target surface.

[0119] Magnetron sputtering differentiates between balanced and unbalanced magnetron sputtering. An unbalanced magnetron is simply a design where the magnetic flux from one pole of the magnets located behind the target is greatly unequal to the other while in a balanced magnetron the magnetic flux between the poles of the magnet are equal. Compared to balanced magnetron sputtering, unbalanced magnetron sputtering increases the substrate ion current and thus the density of the substrate coating. In one embodiment a sputtering technique such as RF sputtering, DC sputtering or magnetron sputtering is used to deposit the barrier layer onto the substrate layer. The magnetron sputtering can include balanced or unbalanced magnetron sputtering. In one embodiment, the barrier layer is a sputtered barrier layer.

[0120] The barrier stack may be applied onto a substrate, such as a polycarbonate or a PET substrate. In some embodiments a barrier layer may be formed with the aid of a respective substrate. The substrate may be plasma treated and coated with alumina barrier material via magnetron sputtering, thereby forming a barrier layer.

[0121] In some embodiments a further material such as ITO may be deposited, e.g. magnetron sputtered, over the multilayer film to form an ITO coating after the multilayer film has been formed. If the encapsulation barrier stack is to be used in Passive Matrix displays, only ITO lines are required instead of a complete coat of IOT. A protective liner is subsequently formed on the ITO coating. Any suitable material may be used, depending on the intended purpose, e.g. scratch resistant films or glare reduction films, such as MgF/LiF films. After forming the protective film, the encapsulation barrier stack is packed in aluminium foil packaging or slit into predetermined dimensions for assembly with other components.

[0122] As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, other compositions of matter, means, uses, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding exemplary embodiments described herein may likewise be utilized according to the present invention.

EXEMPLARY EMBODIMENTS

[0123] Typical embodiments of a multi-layer barrier stack design of the present invention include a barrier oxide film deposited onto planarized or non-planarized plastic substrate (stretchable or non-stretchable). Functionalized single or multi-layer nano-materials are deposited on to barrier oxide films. For example, functionalized nano-particles consist of polymer-encapsulated nano-particles and/or functionalized nanoparticle with organic species may be deposited on to a barrier oxide film as a functionalized nanoparticle layer. The functionalized nanoparticles can penetrate into the pores of the barrier oxide film and enhance the barrier properties. The combination of mutually chemically interconnected organic and inorganic nanoparticles results in coatings with very low permeability of gases. If polymer is encapsulated on to the nanoparticle, the ratio of polymer and nanoparticles by weight are preferably 1:4 or less, 1:5 or less, or 1:6 or less.

[0124] The functionalized nanoparticle layer (Nano-layer) can be a multi-nanolayer. These functionalized multi-nanolayers can act as a barrier layers and can also act as a UV blocking layer, anti-reflection layer, to enhance the mechanical properties, which includes adhesion, stretchability, weatherablity and optical properties.

[0125] For example, the first functionalized nanoparticle layer can be a defect sealing layer and anti-reflection layer and the second layer can be a UV blocking layer and third layer may be a light extraction layer. Therefore, in one barrier stack, the multi-functional properties can be obtained.

[0126] In one embodiment, the defect-sealing layer(s) consist of polymer encapsulated titanium nanoparticles, zinc nanoparticles, silica or hollow silica particles. These (polymer encapsulated) particles can be used to enhance the barrier properties of the stack, to block the UV light and have anti-reflection properties in the visible region.

Functionalization Nanoparticles Layer or Multi-Nano Layers

Substrate Materials

[0127] Polymers that may be used in the base substrate in the present invention include both organic and inorganic polymers. Examples of organic polymers which are suitable for forming the base substrate include both high and low permeability polymers such as cellophane, poly(1-trimethylsilyl-1-propyne, poly(4-methyl-2-pentyne), polyimide, polycarbonate, polyethylene, polyethersulfone, epoxy resins, polyethylene terephthalate (PET), polystyrene, polyurethane, polyacrylate, and polydimethylphenylene oxide. Microporous and macroporous polymers such as styrene-divinylbenzene copolymers, polyvinylidene fluoride (PVDF), nylon, nitrocellulose, cellulose or acetate may also be used. Examples of inorganic polymers which are suitable in the present invention include silica (glass), nano-clays, silicones, polydimethylsiloxanes, biscyclopentadienyl iron, polyphosphazenes and derivatives thereof. The base substrate may also include or consist of a mixture or a combination of organic and/or inorganic polymers. These polymers can be transparent, semi-transparent or completely opaque.

Surface Preparation

[0128] The barrier stacks or glass substrates are rinsed with isopropyl alcohol (IPA) and blow-dried with nitrogen. These processes help to remove macro scale adsorbed particles on the surface. Acetone and methanol cleaning or rinsing is not recommended. After nitrogen blow-dry, the substrates are placed in the vacuum oven, with the pressure of 10-1 mbar, for degassing absorbed moisture or oxygen. The vacuum oven is equipped with fore line traps to prevent hydrocarbon oil back migrating from vacuum pump to the vacuum oven. Immediately after the degassing process, the barrier stacks are transferred to the plasma treatment chamber (e.g. ULVAC SOLCIET Cluster Tool). RF argon plasma is used to bombard the surface of the barrier film with low energy ions in order to remove surface contaminants. The base pressure in the chamber was maintained below 4?10-6 mbar. The argon flow rate is 70 sccm. The RF power is set at 200 W and an optimal treatment time usually 5 to 8 minutes is used depending on the surface condition.

Inorganic Barrier Oxide Films Fabrication

[0129] The sputtering technique, EB evaporation and Plasma Enhanced Physical Vapor deposition methods were used to deposit the metal oxide barrier layer. The unbalanced magnetron sputter system is used to develop high-density oxide barrier films. In this sputtering technique, a metal layer of typically a few mono-layers will be deposited from an unbalanced magnetron and then oxygen will be introduced to the system to create oxygen plasma, directed towards the substrate to provide argon and oxygen ion bombardment for a high packing-density oxide film. This plasma will also increase the reactivity of the oxygen directed onto the growing film surface and provides for more desirable structures. In order to deposit dense films without introducing excessive intrinsic stresses, a high flux (greater than 2 mA/cm.sup.2) of low energy (?25 eV) oxygen and argon ions to bombard the growing barrier oxide films.

[0130] The continuous feedback control unit is used to control the reactive sputtering processes. The light emitted by the sputtering metal in the intense plasma of the magnetron racetrack is one indicator of the metal sputtering rate and the oxygen partial pressure. This indication can be used to control the process and hence achieve an accurate oxide film stoichiometry. By using a continuous feedback control unit from a plasma emission monitor, reproducible films and desirable barrier properties were obtained. Various barrier layers including SiN, Al.sub.2O.sub.3, and Indium tin oxide were prepared by conventional and unbalanced magnetron sputtering techniques and tested the single barrier layer properties.

[0131] In addition, barrier oxide films (SiO.sub.x & Al.sub.2O.sub.3) were produced by EB evaporation and Plasma enhanced physical vapor deposition methods at the speed of 500 meters/min. Coating thickness is 60 nm to 70 nm.

Functionalized Nanoparticle Layer

[0132] The surface modification is a key aspect in the use of nanosized materials (also referred to as nanomaterials here). It is the surface that makes the nanosized materials significantly more useful than conventional non-nanomaterials. As the size of the material decreases, its surface-to-volume ratio increases. This presents considerable advantage to modify properties of nanomaterials through surface functionalization techniques. The functionalized nanoparticles are inclusive of polymer encapsulation on to the nanoparticle and organic species passivated nanoparticles. The functionalization techniques, which includes non-covalent (physical) bond and covalent bond (chemical) that can be applied to the nanoparticles. There are several methods available. Ultrasonic cavitation can be used to disperse nano-sized particles into solvent.

[0133] Covalent functionalization has been widely investigated and has produced an array of modified nanomaterial bearing small molecules, polymers and inorganic/organic species. Since nanomaterials, although quite small, are much larger than molecules, organic molecules can be used to modify the surfaces of these small particles. In addition to controlling the shape and size of the nanoparticles, controlling the surface of nanomaterial with organic chemistry has played a key role in the barrier stack design.

[0134] Surfactants, polymeric surfactants or polymers are employed to passivate or encapsulate the surface of the nanoparticles during or after the synthesis to avoid agglomeration. Generally electrostatic repulsion or steric repulsion can be used to disperse nanoparticles and keep them in a stable colloidal state. Also, surfactants or polymers can be chemically anchored or physically adsorbed on nanomaterials to form a layer stabilization and specific functionalization.

[0135] In one embodiment, the methodology for the preparation of polymer encapsulated nanoparticles is explained as below:

[0136] The commercially available surface functionalized nanoparticles can be selected according to the desired application. Illustrative examples of surface functionalized nanoparticles include, but are not limited, to 1-Mercapto-(triethylene glycol) methyl ether functionalized Zinc nanoparticles ethanol, colloidal dispersion w/dispersant, Aluminum oxide, NanoDur? X1130PMA, 50% in 1,2-propanediol monomethyl ether acetate, colloidal dispersion, Zinc oxide, NanoArc? ZN-2225, 40% in 1,2-propanediol monomethyl ether acetate, colloidal dispersion with dispersant, Zinc oxide, NanoTek? Z1102PMA, 50% in 1,2-propanediol monomethyl ether acetate, colloidal dispersion with dispersant. Examples of silane compounds are inclusive of but limited to alkali, amino, epoxy, methacryl silanes.

[0137] A polymer coating can be established on the nanoparticle core via covalent bonding or physical bonding, for example, by means of in situ polymerized monomers or pre-polymers in a discontinuous phase of an inverse mixture. A so obtained polymer-encapsulated nanoparticle may have a size ranging from about 20 nm to about 1000 nm.

[0138] In one embodiment, the above surface functionalized aluminium oxide (NanoDur) nanoparticles (20 ml) are mixed in the Ethyl acetate (10 ml), 3-Methacryloxypropyltrimethoxysilane (10 ml) and surfactant (0.5% by weight). THINKY ARE-250 Mixer can undertake the mixing of the above mentioned solution. Sonication time is 2 hours at 28? C. After that, the monomer can be added by 4% to 6% (2 to 3 ml) by weight of the total solution. The sonication can be undertaken typically 2 hours to 12 hours. The monomer is diluted in the solvent and adsorbed and chemically anchored on the nanoparticles during the Sonication process.

[0139] The coating process can be undertaken by spin coating, inkjet printing, slot die coating, gravure printing or any wet coating processes. Then the monomer is cured under UV or heat curing or EB curing processes.

[0140] The functionalized nano-particles can penetrate effectively in to pores or the defects of barrier oxide layer and plug the defects. And also, improves the bond strength between barrier oxide layer and functionalized nano-particle layer. The high packing density of the nanoparticle coating can be obtained by the suitable functionalization techniques (coating thickness in the range of 50 nm to few hundred nanometers) on to barrier oxide films. The functionalized nano-particles thickness may be determined based on barrier oxide film coating thickness.

[0141] In a preferred embodiment, the majority of the polymer coated nano-particles of metal or metal oxide particles and organic species passivated nanoparticles, which include metal and metal oxide, are rod like with a diameter of 10 to 50 nm and length up to 200 nm. The diameter and size of the particles are chosen in such a way that they do not influence the transparency of the eventual coatings. The packing density of the nano-particle is determined by the shape and size distribution of the nano-particles. Therefore, it may be advantageous to use nano particles of different shapes and sizes to precisely control the surface nano-structure for the effective sealing of defects of barrier oxide layer.

[0142] Polymer encapsulated Carbon nanotubes (CNTs)/carbon particles can be also used to seal the defects of the pinholes. Typically it is advantageous to employ the maximum amount of absorbent particles in order to increase the ability of the sealing layer to seal the barrier oxide films defects and also absorb and retain water and oxygen molecules. The characteristic wavelength is defined as the wavelength at which the peak intensity of OLED or any other displays output light spectrum occurs. When the encapsulation layer designed for Transparent OLED or see-through displays, the size of the particles may be typically less than ? and preferably less than ? of the characteristic wavelength. Typically these ratios correspond to particle sizes of less than 200 nm and preferably less than 100 nm. In some barrier designs, larger particles may be desirable, for example where it is required to have scattering of the emitted light.

Calcium Degradation Test Method

[0143] After the plasma treatment process, the barrier stacks are transferred to the vacuum evaporation chamber (thermal evaporation) under vacuum where the two metal tracks that are used as electrodes has dimension 2 cm by 2 cm. The sensing element is fabricated in between the two electrodes and designed with 1 cm long, 2 cm wide and 150 nm thick. The measured resistivity of the sensor element is 0.37 ?-cm. After the deposition process, a load lock system is used to transfer the sample to a glove box under dry nitrogen at atmospheric pressure. After the calcium deposition, a 100 nm silver protection layer were deposited for the qualitative analysis (test cell type A), cf. FIG. 4.

[0144] To accelerate the permeation a silver protection layer was deposited for the qualitative analysis (test cell type A). In the case of the quantitative resistance measurement method (test cell type B), cf. FIG. 5, 300 nm silver was used for the conductive track, 150 nm calcium was used as the sensor and 150 nm lithium fluoride was used as a protection layer. After the deposition processes, a UV curable epoxy was applied on the rim of the substrate and then the whole substrate was sealed with a 35 mm?35 mm glass slide. The getter material was attached to the 35 mm?35 mm cover glass slide in order to absorb any water vapour due to out gassing or permeation through the epoxy sealing. A load lock system was used for the entire process and the test cells were encapsulated in the glove box under dry nitrogen at atmospheric pressure. For the testing, the samples were placed into a humidity chamber at constant temperature and humidity of 80? C. & 90% RH respectively. These were viewed optically at regular intervals for a qualitative degradation test and analysis of the defects, and measured electrically for the quantitative analysis of the Calcium degradation.

[0145] The Calcium test cell's conductive track terminals are connected to a constant current source (Keithey source meter), which is interfaced with a computer. Resistance of the calcium sensor/silver track is monitored every second and plotted automatically by the computer using lab view software. A Dynamic Signal Analyzer with a FFT analysis is proposed to take the noise spectrum measurement automatically at periodic intervals of one second.

Experimental Details & Results

Polymer Encapsulated Nanoparticles Layer (Cf. FIG. 6)Surface Topography

[0146] In one example, a solvent mixture of IPA:Ethyleactate in the ratio 5:15 ml is mixed, and 3-Methacryloxypropyltrimethoxysilane 10 ml added. The surfactant Dow corning FZ 2110 is further added to 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave)3 ml is then added in the above mixture. The mixture is kept in sonication for 2 hours. The surface functionalized nanoparticle Aluminum oxide, NanoDur? X1130PMA, 50% in 1,2-propanediol monomethyl ether acetate20 ml added to the solvent/monomer mixture and sonicated for few hours. The above mixture was then spin coated and cured. The formulation was undertaken under inert gas environment. The set of experiments were carried out with different mixture of nanoparticles and spin coated onto the plain polymer substrate, barrier coated plastic substrates and aluminum oxide Anodise?. FIG. 7 and FIG. 8 show the surface morphology of the coated polymer encapsulated nanoparticles.

[0147] The polymer encapsulated nanoparticle were dispersed on 47 micron thick aluminum oxide Anodise?, which has several pin holes with a diameter of 200 nm, and SEM pictures were taken as shown in FIG. 9, 10, 11, and FIGS. 13C and D. The Anodise? is rim sealed on to the plastic substrate.

[0148] FIG. 12 shows a TEM image illustrating that the nanoparticles are distributed in the polymer layer/film (50 nm scale). It is just shown as comparative analysis purpose in order to discriminate the encapsulated nanoparticles vs. nanoparticle distributed in polymer matrix.

[0149] FIG. 13A shows a SEM image of the distribution of aluminum oxide nanoparticles in a polymer matrix as known in the art at 35.000? magnification. FIG. 13B shows a SEM image of prior art aluminium oxide nanoparticles before encapsulation at 70.000? magnification. FIG. 13C shows a SEM image of the polymer encapsulated nanoparticles of the invention at 100.000? magnification and FIG. 13D shows a SEM image of a layer of polymer encapsulated nanoparticles of the invention.

Embodiment 1

[0150] 1. Plastic substratePET

[0151] 2. Polymer encapsulated nanoparticle coating

[0152] 3. SiN layerCVD method

[0153] 4. polymer encapsulated nanoparticle coating

[0154] 5. SiN layerCVD method

[0155] Nano Solution Preparation:

[0156] The solvent IPA:Ethyleactate 5:15 ml ratio is mixed, and 3-Methacryloxypropyltrimethoxysilane (10 ml) added and then surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave)(3 ml) is then added to the above mixture. The mixture is kept in sonication for 2 hours. The surface functionalized nanoparticle Aluminum oxide, NanoDur? X1130PMA, 50% in 1,2-propanediol monomethyl ether acetate20 ml is added to the solvent/monomer mixture and sonicated for a few hours. The above mixture was then spin coated and cured. The formulation was undertaken under inert gas environment. The set of experiments were carried out with different mixture of nanoparticles and spin coated onto the plain polymer substrate, barrier coated plastic substrates and aluminum oxide Anodisk?. The entire deposition/coating process was carried out by a batch process.

Embodiment 2

[0157] 1. Plastic substratePET

[0158] 2. SiOx layerhigh speed manufacturing process

[0159] 3. polymer encapsulated nanoparticle coating

[0160] 4. SiOx layerhigh speed manufacturing process

[0161] Nano Solution Preparation:

[0162] The solvent IPA:Ethyleactate (5:15 ml) ratio is mixed, and 3-Methacryloxypropyltrimethoxysilane (10 ml) is added and then surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave)(3 ml) is then added to the above mixture. The mixture kept is in sonication for 2 hours. The surface functionalized nanoparticle Aluminum oxide, NanoDur? X1130PMA, 50% in 1,2-propanediol monomethyl ether acetate20 ml added to the solvent/monomer mixture and sonicated for few hours. The above mixture was then spin coated and cured. The formulation was undertaken under inert gas environment. The set of experiments were carried out with different mixture of nanoparticles and spin coated onto the plain polymer substrate, barrier coated plastic substrates and aluminum oxide anodisk. Barium titanium ethylhexano-isopropoxide in isopropanol is used to produce 5% BaTiO.sub.3 and to this mixture is added 3-Methacryloxypropyltrimethoxysilane and surfactant Dow corning FZ 2110 and sonicated for 2 hours. A Thinky ARE 250 mixer (available from INTERTRONICS, Oxfordshire, United Kingdom) is then used to mixe the above Al.sub.2O.sub.3 mixture and BaTiO.sub.3 mixtures before the coating process. The entire deposition/coating process was carried out by a batch process. The SiOx layers were both formed by plasma assisted electron beam evaporation process.

Embodiment 3

[0163] 1. Plastic substratePET

[0164] 2. Polymer encapsulated nanoparticle layer

[0165] 3. SiOx layerhigh speed manufacturing process

[0166] 4. Polymer encapsulated nanoparticle coating layer 1 (Defects sealing)

[0167] 5. Polymer encapsulated nanoparticle coating layer 2 (anti-reflectance)

[0168] 6. SiOx layerhigh speed manufacturing process

[0169] Nano Solution Preparation:

[0170] The solvent IPA:Ethyleactate (5:15 ml ratio) is mixed, and 3-methacryloxypropyltrimethoxysilane (10 ml) added and surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave)(3 ml) is then added to the above mixture. The mixture is kept in sonication for 2 hours. The surface functionalized nanoparticle Aluminum oxide, NanoDur?X1130PMA, 50% in 1,2-propanediol monomethyl ether acetate20 ml is added to the solvent/monomer mixture and sonicated for few hours. The above mixture was then spin coated and cured. The formulation was undertaken under inert gas environment. The set of experiments were carried out also with a different mixture of nanoparticles and spin coated onto the plain polymer substrate, barrier coated plastic substrates and aluminum oxide Anodisk?. For this purpose barium titanium ethylhexanol-isopropoxide in isopropanol was used to produce 5% BaTiO.sub.3 and to this mixture 3-methacryloxypropyltrimethoxysilane and surfactant Dow corning FZ 2110 is further added and sonicated for 2 hours. A Thinky ARE 250 mixer (see above) is then used to mix the above Al.sub.2O.sub.3 mixture and BaTiO.sub.3 mixtures before the coating process.

[0171] In the layer 2, the Zinc oxide, NanoTek? Z1102PMA, 50% in 1,2-propanediol monomethyl ether acetate, colloidal dispersion with dispersant, and 3-Methacryloxypropyltrimethoxysilane 10 ml is added and surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave)(3 ml) is then added to the above mixture. The mixture is kept in sonication for 2 hours. The surface modified Zinc oxide, NanoTek? in 1,2-propanediol monomethyl ether acetate, colloidal dispersion with dispersant ?20 ml added to the solvent/monomer mixture and sonicated for few hours. The above mixture was then spin coated and cured. The formulation was undertaken under inert gas environment. Titanium in isopropanol to produce 5% of titanium oxide and 3-Methacryloxypropyltrimethoxysilane and then doped surfactant Dow corning FZ 2110 is added. This mixture was sonicated for 2 hours. A Thinky ARE 250 mixer is used to mix the above zinc oxide mixture and BaTiO.sub.3 mixtures before the coating process. The entire deposition/coating process was carried out by a batch process. The SiOx layers were both formed by plasma assisted electron beam evaporation process.

Embodiment 4

[0172] 1. Plastic substratePET

[0173] 2. Polymer encapsulated nanoparticle layer

[0174] 3. SiOx layerhigh speed manufacturing process

[0175] 4. Polymer encapsulated nanoparticle coating layer 1 (defects sealing)

[0176] 5. Polymer encapsulated nanoparticle coating layer 2 (anti-reflectance)

[0177] 6. SiOx layerhigh speed manufacturing process

[0178] Nano Solution Preparation:

[0179] The solvent IPA:Ethyleactate (5:15 ml) ratio is mixed, and 3-Methacryloxypropyltrimethoxysilane (10 ml) and surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave)(3 ml) is then added to the above mixture. The mixture is kept in sonication for 2 hours. The surface functionalized nanoparticle Aluminum oxide, NanoDur? X1130PMA, 50% in 1,2-propanediol monomethyl ether acetate20 ml is added to the solvent/monomer mixture and sonicated for few hours. The above mixture was then spin coated and cured. The formulation was undertaken under inert gas environment. The set of experiments were carried out with different mixture of nanoparticles and spin coated onto the plain polymer substrate, barrier coated plastic substrates and aluminum oxide Anodisk?. Barium titanium ethylhexano-isopropoxide in isopropanol is used to produce 5% BaTiO.sub.3 and 3-methacryloxypropyltrimethoxysilane added and surfactant Dow corning FZ 2110 is further added and sonicated for 2 hours. A Thinky ARE 250 mixer is then used to mix the above Al.sub.2O.sub.3 mixture and BaTiO.sub.3 mixture before the coating process.

[0180] In the layer 2, the Zinc oxide, NanoTek? Z1102PMA, 50% in 1,2-propanediol monomethyl ether acetate, colloidal dispersion with dispersant and 3-methacryloxypropyltrimethoxysilane (10 ml) is added and surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave) 3 ml is then added to the above mixture. The mixture is kept in sonication for 2 hours. The surface modified Zinc oxide, NanoTek? in 1,2-propanediol monomethyl ether acetate, colloidal dispersion with dispersant(20 ml) is added to the solvent/monomer mixture and sonicated for few hours. The formulation was undertaken under inert gas environment. Titanium in isopropanol to produce 5% of titanium oxide and 3-Methacryloxypropyltrimethoxysilane added and then doped surfactant Dow corning FZ 2110. This mixture was sonicated for 2 hours. A Thinky ARE 250 mixer was used to mix the above zinc oxide and titanium oxide mixture and BaTiO.sub.3 mixture before the coating process. The entire deposition/coating process was carried out by a batch process. The SiOx layers were both formed by plasma assisted electron beam evaporation process.

Embodiment 5

[0181] 1. Plastic substratePET

[0182] 2. Al.sub.2O.sub.3 layersputtering manufacturing process

[0183] 3. Polymer encapsulated nanoparticle coating layer 1 (sealing layer)

[0184] 4. Nanoparticle distributed in polymer matrix

[0185] 5. Al.sub.2O.sub.3 layersputtering manufacturing process

[0186] Nano Solution Preparation: The solvent IPA:Ethyleactate (5:15 ml) ratio is mixed, and 3-Methacryloxypropyltrimethoxysilane (10 ml) and surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave)(1.5 ml) is then added to the above mixture. The mixture is kept in sonication for 2 hours. The surface functionalized nanoparticle Aluminum oxide, BYK 3610, 30% in 1,2-propanediol monomethyl ether acetate40 ml is added to the solvent/monomer mixture and sonicated for few hours. The above mixture was then coated in a roll to roll slot die coating process and cured. The formulation was undertaken under inert gas environment. The set of experiments were carried out with different mixture of nanoparticles and coated onto a barrier coated plastic substrates, with Al2O3 being the barrier layer.

[0187] In the layer 2, aluminum oxide, BYK 3610 30% in 1,2-propanediol monomethyl ether acetate (28 ml), colloidal dispersion with dispersant and 3-methacryloxypropyltrimethoxysilane (both 10 ml) is added and surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave) 40 ml is then added to the above mixture. The mixture is kept in sonication for 2 hours. The above mixture was then coated in a roll to roll slot die coating process and UV cured so that the nanoparticles were encapsulated in the polymer matrix. Note in this regard the much higher amount of UV curable monomer (40 ml) used for this layer than the 1.5 ml used for layer 1 in which the nanoparticles are only surface-encapsulated/modified but in which no polymer matrix that embeds the nanoparticles is formed. After that the Al.sub.2O.sub.3 layer is formed by roll to roll sputtering. The resulting barrier stack is shown in FIGS. 16A-B in which FIG. 16A shows the layer 1 and the layer 2, however not the layer of the nanoparticles distributed in the polymer matrix nor the upper Al.sub.2O.sub.3 layer. The layer of the nanoparticles distributed in the polymer matrix and the upper Al.sub.2O.sub.3 layer are shown in FIG. 16B.

Embodiment 6

[0188] 1. Plastic substratePET

[0189] 2. Al.sub.2O.sub.3 layersputtering manufacturing process

[0190] 3. Polymer encapsulated nanoparticle coating layer 1 (defects sealing)

[0191] 4. Al.sub.2O.sub.3 layersputtering manufacturing process

[0192] Nano Solution Preparation: The solvent IPA:Ethyleactate (5:15 ml) ratio is mixed, and 3-Methacryloxypropyltrimethoxysilane (10 ml) and surfactant Dow corning FZ 2110 is further added by 0.5% by total weight of the solution and mixed. The UV curable acrylate monomer (Addision Clear Wave)(1.5 ml) is then added to the above mixture. The mixture is kept in sonication for 2 hours. The surface functionalized nanoparticle Aluminum oxide, BYK 3610, 30% in 1,2-propanediol monomethyl ether acetate40 ml is added to the solvent/monomer mixture and sonicated for few hours. The above mixture was then coated in a roll to roll slot die coating process and cured. The formulation was undertaken under inert gas environment. The set of experiments were carried out with different mixture of nanoparticles and coated onto the plain polymer substrate or an barrier coated plastic substrates, with Al.sub.2O.sub.3 being the barrier layer. After formation of the nanoparticle sealing layer onto the Al.sub.2O.sub.3 oxide, the top Al.sub.2O.sub.3 layer is formed by roll to roll sputtering. An image (cross-section) of the resulting barrier stack is shown in FIG. 17 (the upper aluminum layer is not shown in FIG. 17).

TABLE-US-00001 Reduction of WVTR at 60? C. & reflectance in Structure 90% RH Transmittance UV filter UV-visible range Embodiment 1 no calcium oxidation up 88% PET/polymer to 300 hours encapsulated 8 ? 10.sup.?4 g/m.sup.2 .Math. day nanolayer/SiN (SiN deposited by CVD process) Embodiment 1 no calcium oxidation up 87% PET/polymer to 1600 hours. encapsulated 2 ? 10.sup.?6 g/m.sup.2 .Math. day nanolayer/SiN/polymer encapsulated nanolayer/SiN Embodiment 2 no calcium oxidation up 88% PET/SiOx alone (by to 2 hours > 2 g/m.sup.2 .Math. day high speed manufacturing process) Embodiment 2 no calcium oxidation up 88% PET/SiOx/polymer to 300 hours encapsulated 6 ? 10.sup.?4 g/m.sup.2 .Math. day nanolayer/SiOx Embodiment 3 no calcium oxidation up 88% 30% at 400 hours 350 nm 3 ? 10?4 g/m.sup.2 .Math. day Embodiment 4 no calcium oxidation up 88% 5 to 7% to 360 hours 4 ? 10?4 g/m.sup.2 .Math. day Embodiment 5 Less than 85% 1 ? 10.sup.?4 g/m.sup.2 .Math. day Embodiment 6 Less than 85% 1 ? 10.sup.?4 g/m.sup.2 .Math. day

[0193] Adhesion Test:

[0194] The polymer-encapsulated nanolayer as described in embodiment 1 was deposited on to aluminum oxide coated PET substrate. The adhesion test was performed as per the ASTM STD 3359. The cross-cut tool from BYK was used to make a perpendicular cut on the coatings. The permacel tape was used to peel the coating and the peeled area was inspected using optical microscope. There is no peel-off polymer encapsulated nanolayer from the aluminum oxide coated PET substrate as shown in FIG. 14A and FIG. 14B.

[0195] The listing or discussion of a previously published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.

[0196] The invention illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms comprising, including, containing, etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by exemplary embodiments and optional features, modification and variation of the inventions embodied therein herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention.

[0197] The invention has been described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the invention. This includes the generic description of the invention with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.

[0198] Other embodiments are within the following claims. In addition, where features or aspects of the invention are described in terms of Markush groups, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group.