WO2017142781A1 - Matrix for quantum dot film article - Google Patents

Abstract

Described is a quantum dot film article comprising a quantum dot of an interpenetrating polymer network comprising a cured amine-epoxy resin and a radiation-cured resorcinol dimethacrylate component. The matrix formulations demonstrate improved luminescence, particularly upon ageing.

Description

MATRIX FOR QUANTUM DOT FILM ARTICLE

Background

Quantum dot film articles include quantum dots dispersed in a matrix that is laminated between two barrier layers. The quantum dot articles, which include combinations of green and red quantum dots as fluorescing elements, can enhance color gamut performance when used in display devices such as, for example, liquid crystal displays (LCDs). Summary

The present disclosure is directed to matrix formulations for use in quantum dot articles. More particularly, the present disclosure provides a dual-cure composition comprising a thermally curable resin and a free-radically-curable resin. When cured, the composition provides an interpenetrating polymer network of the resins. The matrix formulations resist ingress from water and/or oxygen, but more significantly provides higher luminescence than comparable matrices and may be maintained over a longer lifetime. For example, quantum dot article prepared with the instant dual-cure resin exhibits higher luminescence than a comparable article using a bisphenol-A based dual cure resin, and the luminescence is more stable after accelerated aging.

In one embodiment, the present disclosure is directed to a quantum dot

composition comprising quantum dots dispersed in a blend of a) a thermally curable component comprising a polyepoxide and a polyamine; and b) a free radically curable component comprising a resorcinol dimethacrylate compound.

In another embodiment, the present disclosure is directed to a quantum dot film article comprising

a first barrier layer;

a second barrier layer; and

a quantum dot layer between the first barrier layer and the second barrier layer, the quantum dot layer including quantum dots dispersed in a matrix comprising a cured matrix composition, wherein the matrix composition includes a blend of a) a thermally curable epoxy-amine component comprising a polyepoxide and a polyamine; and b) a free radically curable component comprising a resorcinol dimethacrylate compound. The compositions comprising composite fluorescent particles (quantum dots) and the curable composition described herein can be used in coatings and films for use in optical displays and lighting applications. The fluorescent semiconductor nanoparticles emit a fluorescence signal at a second wavelength of light when excited by a first wavelength of light that is shorter than the second wavelength of light.

As used herein

"Alkyl" means a linear or branched, cyclic or acylic, saturated monovalent hydrocarbon.

"Alkylene" means a linear or branched unsaturated divalent hydrocarbon.

"Alkenyl" means a linear or branched unsaturated hydrocarbon.

"Heteroalkyl" includes both straight-chained, branched, and cyclic alkyl groups with one or more heteroatoms independently selected from S, O, and N with both unsubstituted and substituted alkyl groups. Unless otherwise indicated, the heteroalkyl groups typically contain from 1 to 20 carbon atoms. "Heteroalkyl" is a subset of

"heterohydrocarbyl containing one or more S, N, O, P, or Si atoms" described below.

Examples of "heteroalkyl" as used herein include, but are not limited to, methoxy, ethoxy, propoxy, 3,6-dioxaheptyl, 3-(trimethylsilyl)-propyl, 4-dimethylaminobutyl, and the like. Unless otherwise noted, heteroalkyl groups may be mono- or polyvalent, i.e. monovalent heteroalkyl or polyvalent heteroalkylene. "Aryl" is an aromatic group containing 5-18 ring atoms and can contain optional fused rings, which may be saturated, unsaturated, or aromatic. Examples of an aryl groups include phenyl, naphthyl, biphenyl, phenanthryl, and anthracyl. Heteroaryl is aryl containing 1-3 heteroatoms such as nitrogen, oxygen, or sulfur and can contain fused rings. Some examples of heteroaryl groups are pyridyl, furanyl, pyrrolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, indolyl, benzofuranyl, and benzthiazolyl. The aryl groups may be unsubstituted, or substituted with one of more alkyl, alkoxy or halo groups.

"Heteroaryl" is aryl containing 1-3 heteroatoms such as nitrogen, oxygen, or sulfur and can contain fused rings. Some examples of heteroaryl groups are pyridyl, furanyl, pyrrolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, indolyl, benzofuranyl, and benzthiazolyl. Unless otherwise noted, aryl and heteroaryl groups may be mono- or polyvalent, i.e.

monovalent aryl or polyvalent arylene. "Alkaryl" means an alkyl group attached to an aryl group, such as methylphenyl. "Arylene" means a polyvalent, aromatic, such as phenylene, naphthalene, and the like.

"Aralkyl" means a group defined above with an aryl group attached to the alkylene,

"Hydrocarbyl" is used to include alkyl, aryl, aralkyl and alkylaryl. The hydrocarbyl group may be mono-, di- or polyvalent.

"(hetero)hydrocarbyl" is inclusive of hydrocarbyl alkyl and aryl groups, and heterohydrocarbyl heteroalkyl and heteroaryl groups, the later comprising one or more catenary (in-chain) oxygen heteroatoms such as ether, thioether or amino groups.

Heterohydrocarbyl may optionally contain one or more catenary (in-chain) functional groups including ester, amide, urea, urethane, and carbonate functional groups. Unless otherwise indicated, the non-polymeric (hetero)hydrocarbyl groups typically contain from 1 to 60 carbon atoms. Some examples of such heterohydrocarbyls as used herein include, but are not limited to, methoxy, ethoxy, propoxy, 4-diphenylaminobutyl, 2-(2'- phenoxyethoxy)ethyl, 3,6-dioxaheptyl, 3,6-dioxahexyl-6-phenyl, in addition to those described for "alkyl", "heteroalkyl", "aryl", and "heteroaryl" supr

The term "composite particle" as used herein refers to a nanoparticle, which is typically in the form of a core/shell nanoparticle (preferably, nanocrystal), having the stabilizing additive combined with, attached to, or associated with, the core/shell nanoparticle. Such composite particles are useful as "quantum dots," which have size dependent, tunable emission in the near ultraviolet (UV) to far infrared (IR) range as a result of the use of a semiconductor material.

The term "nanoparticle" refers to a particle having an average particle diameter in the range of 0.1 to 1000 nanometers such as in the range of 0.1 to 100 nanometers or in the range of 1 to 100 nanometers. The term "diameter" refers not only to the diameter of substantially spherical particles but also to the distance along the smallest axis of the structure. Suitable techniques for measuring the average particle diameter include, for example, scanning tunneling microscopy, light scattering, and transmission electron microscopy. A "core" of a nanoparticle is understood to mean a nanoparticle (preferably, a nanocrystal) to which no shell has been applied or to the inner portion of a core/shell nanoparticle. A core of a nanoparticle can have a homogenous composition or its composition can vary with depth inside the core. Many materials are known and used in core nanoparticles, and many methods are known in the art for applying one or more shells to a core nanoparticle. The core typically has a different chemical composition than the shell of the core/shell nanoparticle.

As used herein, the term "actinic radiation" refers to radiation in any wavelength range of the electromagnetic spectrum. The actinic radiation is typically in the ultraviolet wavelength range, in the visible wavelength range, in the infrared wavelength range, or combinations thereof. Any suitable energy source known in the art can be used to provide the actinic radiation.

Brief Description of the Drawings

FIG. 1 is a schematic side elevation view of an edge region of an illustrative film article including quantum dots.

FIG. 2 is a flow diagram of an illustrative method of forming a quantum dot film.

FIG. 3 is a schematic illustration of an embodiment of a display including a quantum dot article.

FIG. 4 is a schematic illustration of a white point measurement system.

Detailed Description

The present disclosure provides a curable composition comprising quantum dots and a dual-cure composition having a thermally-curable component and a free-radically curable component. More specifically, the dual-cure composition comprising a free- radically polymerizable dimethacylate resorcinol component and a thermally curable epoxy-amine component.

An interpenetrating polymer network is formed by the addition of a free-radically curable component to thermally curable epoxy-amine component forming a polymeric matrix for quantum dots. The free-radically curable methacrylate component increases a viscosity of the thermally curable epoxy-amine component and reduces defects that would otherwise be created during the thermal acceleration of the epoxy amine. The free- radically curable methacrylate component is provided in a relatively low level (e.g., 5-50 or 5-30 wt.%) without reducing the functional properties of the epoxy amine polymer. Following radiation cure, the viscosity of the system is increased greatly allowing for easier handling of the product on the coating and processing line. The radiation cure can occur right after lamination of the two barrier films of the quantum dot article. Thus, the increase in viscosity locks in the coating quality right after lamination. The radiation cure of the methacrylate portion of the curable composition provides greater control over coating, curing and web handling as compared to traditional thermal curing of an epoxy only composition.

The curable composition further comprises a thermally curable epoxy resin.

Suitable epoxy resins include monomeric or oligomeric epoxy compounds that can be aliphatic, alicyclic, aromatic, or heterocyclic. These materials generally have, on the average, >1 polymerizable epoxy group per molecule. Some epoxy resins have >1.5 or > 2 polymerizable epoxy groups per molecule. The oligomeric epoxides can be linear oligomers having terminal epoxy groups (for example, a diglycidyl ether of a

polyoxyalkylene glycol), oligomers having skeletal epoxy units (for example,

polybutadiene polyepoxide), or oligomers having pendant epoxy groups (for example, a glycidyl methacrylate oligomer or co-oligomer). The epoxides can be pure compounds or can be mixtures of compounds containing one, two, or more epoxy groups per molecule. These epoxy-containing materials can have a backbone of any type and with any suitable substituent group thereon that does not substantially interfere with cure. Illustrative of permissible substituent groups include halogens, ester groups, ethers, sulfonate groups, siloxane groups, nitro groups, phosphate groups, and the like. The average molecular weight of the epoxy-containing materials can vary from about 58 g/mole to about 1000 g/mole or more.

Useful epoxy resins include glycidyl ether compounds of Formula I:

where R²⁰ is (hetero)hydrocarbyl group containing at having a valence of m, and m is > 2, preferably > 2. The compounds of Formula IV may include a mixture of compounds having an average functionality of two or greater. R may be derived from any (hetero)hydrocarbyl groups, including aliphatic and aromatic polyols or polyacids. R²⁰ may optionally further include one or more functional groups including pendent hydroxyl, amide, ester, or cyano groups or catenary (in-chain) ether, urea, urethane, ester, amides, and thioether functional groups

In one embodiment, R²⁰ comprises a non-polymeric aliphatic or cycloaliphatic moiety having from 1 to 30 carbon atoms. In another embodiment, R²⁰ is polymeric and comprises a polyoxyalkylene, polyester, polyolefin, polyacrylate, or polysiloxane polymer having pendent or terminal reactive epoxy groups. Useful polymers include, for example, epoxy -terminated polyethylenes or polypropylenes, and epoxy -terminated poly(alkylene oxides). In a preferred embodiment, R²⁰ is a 1,3-phenylene (i.e. resorcinol diglycidyl ether).

Exemplary epoxides are glycidyl ethers of polyhydric phenols that can be obtained by reacting a polyhydric phenol with an excess of a chlorohydrin such as epichlorohydrin (for example, the diglycidyl ether of 2,2-bis-(2,3-epoxypropoxyphenol)-propane or the diglycidyl ether of resorcinol). Additional examples of epoxides of this type are described in U.S. Patent No. 3,018,262, and in Handbook of Epoxy Resins, Lee and Neville, McGraw-Hill Book Co., New York (1967).

Numerous commercially available epoxy resins can be utilized. In particular, epoxides that are readily available include resins of octadecylene oxide, epichlorohydrin, styrene oxide, vinyl cyclohexene oxide, glycidol, glycidyl methacrylate, diglycidyl ethers of Bisphenol A (for example, EPON 828, EPON 825, EPON 1004, and EPON 1001 from Hexion Inc. Columbus, OH) as well as DER 221 , DER 332, and DER 334 from Dow Chemical Co., Midland, MI), vinylcyclohexene dioxide (for example, ERL 4206 from Union Carbide), 3,4-epoxycyclohexylmethyl-3,4- epoxy cyclohexene carboxylate (for example, ERL 4221 , CYRACURE UVR 6110, and C YRACURE UVR 6105 from Union Carbide), 3,4-epoxy-6-methylcyclohexylmethyl-3,4- epoxy-6-methyl-cyclohexene carboxylate (for example, ERL 4201 from Union Carbide), bis(3,4-epoxy-6- methylcyclohexylmethyl) adipate (for example, ERL 4289), bis(2,3-epoxycyclopentyl) ether (for example, ERL 0400), aliphatic epoxy modified from polypropylene glycol (for example, ERL 4050 and ERL 4052), dipentene dioxide (for example, ERL 4269), epoxidized polybutadiene (for example, OXIRON 2001 from FMC Corp.), silicone resin containing epoxy functionality, flame retardant epoxy resins such as brominated bisphenol-type epoxy resins (for example, DER 580), 1 ,4-butanediol diglycidyl ether of phenol formaldehyde novolak (for example, DEN 431 and DEN 438 from Dow

Chemical), resorcinol diglycidyl ether (for example, KOPOXITE from Koppers Company, Inc.), bis(3,4-epoxycyclohexylmethyl)adipate (for example, ERL 4299 or CYRACURE UVR 6128), 2-(3,4-epoxycyclohexyl-5, 5-spiro-3,4- epoxy) cyclohexane-meta-dioxane (for example, ERL-4234), vinylcyclohexene monoxide, 1 ,2-epoxyhexadecane (for example, CYRACURE UVR- 6216), alkyl glycidyl ethers such as alkyl Cs-Cio glycidyl ether (for example, HELOXY MODIFIER 7 from Hexion Inc., Columbus, OH), alkyl C12- Ci4 glycidyl ether (for example, HELOXY MODIFIER 8 from Hexion Inc.), butyl glycidyl ether (for example, HELOXY MODIFIER 61 from Hexion Inc.), cresyl glycidyl ether (for example, HELOXY MODIFIER 62 from Hexion Inc.), p-tert-butylphenyl glycidyl ether (for example, HELOXY MODIFIER 65 from Hexion Inc.), polyfunctional glycidyl ethers such as diglycidyl ether of 1 ,4-butanediol (for example, HELOXY

MODIFIER 67 from Hexion Inc.), diglycidyl ether of neopentyl glycol (for example, HELOXY MODIFIER 68 from Hexion Inc.), diglycidyl ether of cyclohexanedimethanol (for example, HELOXY MODIFIER 107 from Hexion Inc.), trimethylol ethane triglycidyl ether, trimethylol propane triglycidyl ether (for example, HELOXY 48 from Hexion Inc.), polyglycidyl ether of an aliphatic polyol (for example, HELOXY MODIFIER 84 from Hexion Inc.), polyglycol diepoxide (for example, HELOXY MODIFIER 32 from Hexion Inc.), bisphenol F epoxides (for example, EPON 862 from Hexion Inc. and Araldite GY- 281 from Huntsman Advanced Materials), and 9,9-bis[4-(2,3-epoxypropoxy)- phenylfluorenone (for example, EPON 1079 from Hexion Inc.).

Other useful epoxy-containing materials include those that contain cyclohexene oxide groups such as epoxycyclohexanecarboxylates, typified by 3,4- epoxy cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-2- methylcyclohexylmethyl-3,4-epoxy-2-methylcyclohexane carboxylate, and bis(3,4-epoxy- 6-methylcyclohexylmethyl) adipate. A more detailed list of useful epoxides of this nature is set forth in U.S. 3,117,099 (Proops et al).

Other useful epoxy resins are well known and contain such epoxides as epichlorohydrins, alkylene oxides (for example, propylene oxide), styrene oxide, alkenyl oxides (for example, butadiene oxide), and glycidyl esters (for example, ethyl glycidate). Still other useful epoxy resins include epoxy-functional silicones such as those described in U.S. 4,279,717 (Eckberg et al.), which are commercially available from the General Electric Company. These epoxy resins are poly dimethyl siloxanes in which 1 to 20 mole percent of the silicon atoms have been substituted with epoxyalkyl groups (preferably, epoxy cyclohexylethyl, as described in U.S. 5,753,346 (Leir et al.)).

Blends of various epoxy-containing materials can also be utilized. Suitable blends can include two or more weight average molecular weight distributions of epoxy- containing compounds such as low molecular weight epoxides (e.g., having a weight average molecular weight below 200 g/mole), intermediate molecular weight epoxides (e.g., having a weight average molecular weight in the range of about 200 to 1000 g/mole), and higher molecular weight epoxides (e.g., having a weight average molecular weight above about 1000 g/mole). Alternatively or additionally, the epoxy resin can contain a blend of epoxy-containing materials having different chemical natures such as aliphatic and aromatic or different functionalities such as polar and non-polar.

The thermally curable component further includes a polyamine that includes at least two amine groups. The polyamine has a non-aromatic, acyclic or cyclic aliphatic backbone, particularly those containing at least two amino groups connected to

a cycloaliphatic ring or ring-system. In some preferred embodiments, the first amino- functional compound is represented by Formula II:

FhN— CnFhn— A— CmFhm— Fh II wherein A is an acyclic, monocyclic or a polycyclic alkylene group, or an acyclic, monocylic or a polycyclic heteroalkylene group, and m and n are integers each independently selected from 0 to 5, and m and n are integers. In Formula II, m and n are each independently selected in the range from 0 to 5, or 1 to 5. The term alkylene group as used herein refers to a bivalent radical formed by removing a hydrogen atom from each of two different carbon atoms on a monocyclic or a polycyclic alkyl compound. The mono- or polycyclic alkyl can include a single ring, two rings, three rings, or multiple rings. The heteroalkylene groups can include polyether amines.

In various non-limiting embodiments, the monocyclic or polycyclic alkylene A groups can have up to 20 carbon atoms, up to 16 carbon atoms, up to 14 carbon atoms, up to 12 carbon atoms, up to 10 carbon atoms, or up to 7 carbon atoms. In various non- limiting embodiments, the monocyclic or polycyclic heteroalkylene A groups have up to 20 carbon atoms and up to 4 heteroatoms, up to 16 carbon atoms and up to 4 heteroatoms, up to 12 carbon atoms and up to 3 heteroatoms, or up to 10 carbon atoms and up to 3 heteroatoms. The heteroatoms are selected from oxygen, sulfur, nitrogen, or a

combination thereof. One example of a useful heteroalkylene diamine is 4,7, 10- Trioxatridecane- 1, 13 -diamine.

Non-limiting examples of A groups in Formula II are polycyclic alkylene groups having one or more bicyclo(2.2.1) heptane rings such as those described in Japanese Patent Application Kokai Publication S54004992. Groups of this type are represented by the following Formulas III and IV:

wherein Ri, R₂, R₃, R4, R5 and R₆ each represent either a hydrogen or a methyl group; and x and y each represent either 0 or 1. The asterisks (*) in Formulas III and IV represent the positions where the polycyclic alkylene group A attaches to the amino or alkylamino groups in Formula II.

Specific examples of the first amino-functional compound including the groups represented by the general Formulas II and III are, 3 (or 4), 8(or 9)- diaminomethyltricyclo(5,2,l,0^{2 6}) decane,

10)-diaminomethyltetracyclo(6,2, 1 , 1^{3 6},0^{2 7}) dodecane,

and 2,5(or 6)-diaminomethyl bicyclo(2,2, l)heptane.

Diaminomethyl tricyclodecane is an example of a first amino-functional compound in the amino-functional curing agent. Other compounds suitable as the first amino- functional compound include, but are not limited to, isophorone diamine (IPDA), 1,3- cyclohexanebis(methylamine), and l,4-bis(3-aminopropyl) piperazine. A suitable first amino-functional compound is available from Oxea Corp., Dallas, TX, under the trade designation TCD-diamine, particularly octahydro-4,7-methano-lH-indenedimethylamine (which is also referred to as 3(or 4), 8(or 9)-diaminomethyltricyclo(5,2, l,0^{2 6}) decane). Again, while not wishing to be bound by any theory, presently available evidence indicates that the compact nature of the cyclic backbone can create more compact structures that pack closely together when forming the matrix material 24, which can in some cases slow ingress of water and oxygen.

In other embodiments, the amine component of the epoxy-amine resin is a polyether amine that contains primary and/or secondary amino groups, particularly terminal primary and/or secondary amino groups, attached to a polyether backbone. The polyether backbone can be based on repeat units of propylene glycol (PG), ethylene glycol (EG), mixed EG/PG, polytetramethylene glycol (PTMEG), and combinations thereof. Polyether amines having this core structure can be monoamines, diamines, or triamines.

Suitable polyether amines are represented by the following Formula VII.

R⁵⁰-( HR⁵¹)b VII

In Formula VII, the group R⁵⁰ is a monovalent, divalent or trivalent polyether radical having at least 2, at least 3, at least 5, at least 10, at least 20, or at least 30 groups of formula-(R⁵²-0)-, where R⁵² is a linear or branched alkylene having 1 to 4 carbon atoms, 2 to 4 carbon atoms or 2 to 3 carbon atoms. The group R51 is hydrogen or alkyl (e.g., an alkyl having 1 tolO carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms). The subscript b is equal to 1, 2, or 3. The weight average molecular weight can be up to 5,000 grams/mole, up to 4,000grams/mole, up to 3,000 grams/mole, up to 2,000 grams/mole, up to 600 grams/mole, or up to 300 gram/mole. The weight average molecular weight is often at least 100 grams/mole, at least 120 grams/mole, at least 150 grams/mole, or at least 200 grams/mole.

In other embodiments, the poly ether amine of Formula VII is a poly ether diamine of the following Formula VIII.

H₂N-R⁵⁵-(OR⁵⁶)d-NH₂ VIII

In Formula VIII each group R⁵⁵ and R⁵⁶ is each independently a branched or linear alkylene having 1 to 4 carbon atoms, 2 to 4 carbon atoms, or 2 to 3 carbon atoms. The subscript d is equal to at least 2, at least 3, at least 5, at least 10, at least 20, or at least 30.

Examples of suitable diamines of Formula VIII are commercially available from Huntsman Corporation (Woodlands, TX) under the trade designation JEFF AMINE such as those in the JEFF AMINE D-series (e.g., D-230, D400, D-2000, and D-4000),

JEFF AMINE HK-511, the JEFF AMINE ED-series (e.g., ED-600, ED-900, and ED-2003), the JEFF AMINE EDR series (e.g., EDR-148, and EDR-176), or the JEFF AMINE THF series (e.g., THF-100, THF-140, and THF-170). Other examples of suitable diamines of Formula VIII are commercially available from BASF (Florham Park, NJ) under the trade designation BAXXODUR (e.g., BAXXODUR EC-130 (4,7, 10-trioxatridecane-l, 13- diamine), EC -280 (4,9-dioxadodecane- 1, 12-diamine), EC 301, EC 302 (polypropylene glycol) bis(2-aminopropyl ether)), and EC 303.

In still other embodiments, the polyether amine is a polyether triamine such as those commercially available from Huntsman Corporation (Woodlands, TX) under the trade designation JEFF AMINE, such as those in the JEFF AMINE T-series (e.g., T-403, T- 3000, and T-5,000) and from BASF (Florham Park, NJ) under the trade designation

BAXXODUR (e.g., BAXXODUR (e.g., BAXXODUR EC 110, EC 310, and EC 311).

In yet other embodiments, the polyether amine is a polyether diamine or polyether triamine having secondary amine groups. These polyether amines are commercially available, for example, from Huntsman Corporation (Woodlands, TX) under the trade designation JEFF AMINE such as those in the JEFF AMINE SD-series or ST-series (SD- 213, SD-401, SD-2001, and ST-404). Optionally, the amines may be adducted to a multifunctional epoxy resin by pre- reacting excess amine with some of the epoxy resin, as described by Clive H. Hare in Protective Coatings: Fundamentals of Chemistry and Composition Technology Publishing Company, Pittsburgh, PA (ISBN 0-938477-90-0) Chapter \ 5-Epoxy Systems, pp 187-237. The resulting adducts are essentially high molecular weight amines with epoxy backbones.

Generally the molar ratio of epoxy to amine in the curable composition is about 0.6 to about 1.4 moles epoxy to moles amine.

In various embodiments, the epoxy-amine resin forms about 50 wt.% to about 95 wt.%, or about 70 wt.% to about 95 wt%, of the curable composition, based on the total weight of the curable composition (thermal + radiation curable).

In addition to the epoxy-amine resin, the matrix is formed by curing or hardening a radiation curable component including monomers or oligomers with two methacryl functional groups on a resorcinol backbone ("resorcinol dimethacrylates"), and may further include optional other mono-(meth)acrylates or polyfunctional methacrylates.

Applicants have determined that multifunctional acrylates are not preferred for use in the radiation curable component of the curable composition. Multifunctional acrylates undergo Michael Addition with any amine-containing component of the composition and result in a solution that is unstable. It has been observed that a radiation curable composition with higher functionality acrylates (two or more acryl functional groups) will prematurely cure or gel when an amine-containing material is present. It has also been observed that quantum dot films film articles made with multifunctional acrylates also have relatively poor aging stability.

In one embodiment, the radiation curable composition includes a difunctional monomer, oligomer, or mixture thereof having two methacryl functional groups and a resorcinol group (resorcinol dimethacrylate). In some embodiments, the difunctional monomer or oligomer includes a single methacryl functional group on each end of the resorcinol backbone. A wide variety of backbone chemistries can be selected to provide a quantum dot matrix with good initial and aged optical properties, as well as good barrier and physical properties.

The backbone of the difunctional methacryl monomer or oligomer is derived from resorcinol. Suitable commercially available monomers or oligomers include oligomers such as those generally known as epoxy methacrylates obtained, for example, from the reaction of difunctional resorcinol diglycidyl ether resins reacted with two equivalents of methacrylic acid, or from the reaction of resorcinol with two equivalents of glycidyl methacrylate.

The resorcinol dimethacrylate may comprise resorcinol dimethacrylate per se, or is preferably represented by the formula:

wherein

R¹ is -CH₃

R¹⁰ is a (hetero)hydrocarbyl group, optionally substituted with a hydroxy group; R¹¹ is a (hetero)hydrocarbyl group, which may contain a pendent hydroxyl group.

In some embodiments, R¹⁰ is preferably a Ci-Cio alkylene group.

In a first embodiment, resorcinol dimethacrylates having a single resorcinol group may be prepared by reaction of an epoxy-functional resorcinol, such as resorcinol diglycidyl ether with methacrylic acid, or a hydroxyalkyl methacrylate. Alternatively, resorcinol may be reacted with an epoxyalkyl methacrylate. Similarly, other electrophilic functional groups may be used instead of the epoxy groups, including esters, acyl halides, isocyanates, aziridines, alkyl halides, tosylate and others known to one skilled in the art.

As illustrated, and with reference to Formula V, use of a glycidyl group will yield a resorcinol methacrylate having R¹⁰ groups of -CH2-CH(OH)-CH2-, which may be further functionalized with additional methacrylate groups, alkyl ether, ester, or other functional groups.

In another embodiment, a diol or a diacid may be reacted with two equivalents of resorcinol diglycidyl ether, to produce an intermediate having a resorcinol glycidyl ether group on the termini of the chain. This intermediate may be reacted with methacrylic acid (shown) or a hydroxyalkyl acrylate to provide the requisite methacrylate terminal groups. The diol represented by R³⁰(OH)2 may be any (hetero)hydrocarbyl diol, such as are known in the art. The diol in the reaction scheme may be substituted for a diacid of the formula 4⁰(CO2H)2, and follow the same sequence.

In such embodiments the diol or diacid starting materials preferably have a monocyclic or polycyclic alkylene group as described for group "A" of the polyamine supra. For example, a diol such as tetracyclodecane dimethanol may be may be reacted with two equivalents of resorcinol diglycidyl ether to produce diglycidyl intermediate that may be further reacted with methacrylic acid or a hydroxyalkyl methacrylate to produce a resorcinol dimethacrylate of Formula V.

As another example, a diol may be reacted with an excess diacid to produce a polyester intermediate having acid end groups that may then be reacted with a diglycidyl resorcinol, to produce a second intermediate, that may be functionalized with the requisite methacrylate groups as previous described. Conversely, a diacid may be reacted with an excess of diol to produce an intermediate having hydroxy end groups, then further reacted as before.

The resorcinol dimethacrylate may be 100 wt.% of the free-radically curable component of the curable composition. In various embodiments, the resorcinol dimethacrylate is present in the curable composition at about 50 wt.% to about 99 wt.%, or about 70 wt% to about 95 wt%, based on the total weight (100%) of the radiation-curable component of the curable composition. In turn, the radiation-curable component will comprise 5-50, preferably 5-30 wt.% of the curable composition, the balance being the epoxy-amine resin.

In addition to the resorcinol dimethacrylate compound, the radiation curable component of the curable composition may further comprise additional polyfunctional methacrylate monomers or oligomers or monofunctional (meth)acrylate monomers in amounts of up to 50 wt.% of the radiation-curable component.

Examples include polyalkylene glycol dimethacrylates such as polyethylene glycol (600) dimethacrylate (SR252), polyethylene glycol (400) dimethacrylate (SR603), and polypropylene glycol (400) dimethacrylate (SR644), all available from Sartomer

Americas. Further examples include bisphenol methacrylic compounds such as bisphenol A ethoxylate dimethacrylate and bisphenol A glycerolate dimethacrylate available from Sigma-Aldrich, St. Louis, MO, and 1,3 butanediol dimethacrylate (1,3-BDDMA), diethylene glycol dimethacrylate (DEGDMA), ethylene glycol dimethacrylate (EGDMA), polyethylene glycol 200 dimethacrylate (PEG200DMA), and triethylene glycol dimethacrylate (T3EGDMA) available from BASF Resins, Wyandotte, MI, as well as hydroxyl-containing monomers such as glycerol dimethacrylate, and mixtures thereof. Examples of suitable multifunctional monomers and oligomer include trimethylolpropane trimethacrylate (TMPTA) and ethyoxylated trimethylolpropane trimethyacrylate resins such as SR9035 and SR415 from Sartomer Americas (Exton, PA) and ethoxylated glycerine trimethacrylate resins available from Shin -Nakamura Chemical Company (Wakayama, Japan).

In some embodiments, the radiation curable component may optionally include a monofunctional monomer, monofunctional oligomer, or mixtures thereof having

(meth)acryl functionality, wherein (meth)acryl refers to acrylates and methacrylates.

Such optional monofunctional monomers/oligomers includes a monofunctional

(meth)acrylate monomer or oligomer such as, for example, 2-phenoxy ethyl methacrylate available from Sartomer, USA, LLC under the trade designation SR 339. Other suitable (meth)acryl monomers or oligomers that can be used in the radiation curable composition include, but are not limited to, methyl (meth)acrylate, n-butyl (meth)acrylate, ethyl (meth)acrylate, 2-methylbutyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, hexyl (meth)acrylate, isobornyl (meth)acrylate, octadecyl (meth)acrylate, 2-phenoxyethyl methacrylate available from Sartomer, USA, LLC under the trade designation SR 340, behenyl (meth)acrylate, cyclohexyl (meth)acrylate, iso-tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, tert-butyl (meth)acrylate, ureido (meth)acrylate, 4- tert-butyl cyclohexyl (meth)acrylate, benzyl (meth)acrylate, tetrahydrofurfuryl

(meth)acrylate, gamma-butyrolactone (meth)acrylate,

dicyclpentenyloxyethyl (meth)acrylate (such as FA-512M from Hitachi Chemical, Tokyo Japan) and dicyclpentanyl (meth)acrylate (such as FA-513M from Hitachi

Chemical), phenoxyethyl (meth)acrylate, alkoxylated alkyl(meth)acrylates such as e.g. ethoxyethoxyethyl(meth)acrylate, ethoxyethyl(meth)acrylate,

methoxyethyl(meth)acrylate, methoxyethoxyethyl(meth)acrylate, and mixtures thereof. Examples of suitable monofunctional oligomers include, but are not limited to, hydroxyl- functional or methoxy -functional polyethyleglycol (meth)acrylates such as SR551, SR550, CD553, CD552 from Sartomer Americas, Exton, PA. Hydroxy-containing (meth)acrylate monomers may also be used, such as glycerol mono(meth)acrylate, 2 -hydroxy ethyl (meth)acrylate, 3 -hydroxy propyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3- phenoxy-2-hydroxy propyl methacrylate (Poly sciences, Inc. Warrington, PA), and 3- phenoxy-2-hydroxy propyl acrylate available under the trade designation Denacol DA- 141 from Nagase America, New York, NY. Although amino-functional monomers may be used, such monomer should be methacrylates due to the likelihood of a Michael-addition. Suitable amine-containing methacrylate monomers include N,N-dimethylaminoethyl methacrylate (DMAEMA), Ν,Ν-diethylaminoethyl methacrylate (DEAEMA), and tert- butylaminoethyl methacrylate (TBAEMA), all from BASF (Florham Park, NJ).

In various embodiments, the monofunctional monomer or oligomer with a single

(meth)acryl functional group on a backbone is present in the curable composition at 0 wt.% to < 50 wt.%. If present, then 1 wt.% to 50 wt.%, or 1 wt.% to 20 wt%, or from 1 wt.% to 15 wt.%, based on the total weight of the radiation-curable component of the curable composition.

In some embodiments, the radiation curable composition optionally includes about 0.1 wt% to about 10 wt% of an optional photoinitiator, based on the total weight of the curable composition. A wide variety of photoinitiators may be used, and suitable examples include, but are not limited to, those available from BASF Resins, Wyandotte, MI, under the trade designations IRGACURE 1173, IRGACURE 4265, IRGACURE 819, LUCIRIN TPO, LUCIRIN TPO-L, and DAROCUR 4265; optionally, a thermally activated free-radical initiator may be used. Thermal initiators useful in this invention include compounds that generate free radicals at moderately elevated temperatures.

Suitable classes of thermal initiators include, but are not limited to thermally labile azo compounds and peroxides.

Non-limiting examples of thermally labile azo compounds include those under the trade designation VAZO from the Chemours Company (Wilmington, DE), such as 2,2'- azobisisobutyronirile, 2,2'-azobis-2-methylbutyronitrile, 2,2'- azobis-2- methylvaleronitrile, 2,2'-azobis-2,3-dimethylbutyronitrile, and combinations thereof and the like. Non-limiting examples of peroxides include, but are not limited to organic peroxides under the trade designation LUPEROX available from Arkema Inc.

(Philadelphia, PA), and include cumene hydroperoxide, methyl ethyl ketone peroxide, benzoyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, t-butyl-cumyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, t-butyl peracetate, di-n-propyl

peroxydicarbonate and combinations thereof and the like.

The curable composition comprises about 5 to 50 wt.% of the radiation curable methacrylate component and 50 to 95 wt% of the thermally curable epoxy-amine resin. QDs

The present disclosure provides articles and compositions that comprise composite particles that contain fluorescent semiconductor nanoparticles that can fluoresce when excited with actinic radiation. The composite particles can be used in coatings and films for use in optical displays.

Fluorescent semiconductor nanoparticles emit a fluorescence signal when suitably excited. They fluoresce at a second wavelength of actinic radiation when excited by a first wavelength of actinic radiation that is shorter than the second wavelength. In some embodiments, the fluorescent semiconductor nanoparticles can fluoresce in the visible region of the electromagnetic spectrum when exposed to wavelengths of light in the ultraviolet region of the electromagnetic spectrum. In other embodiments, the fluorescent semiconductor nanoparticles can fluoresce in the infrared region when excited in the ultraviolet or visible regions of the electromagnetic spectrum. In still other embodiments, the fluorescent semiconductor nanoparticles can fluoresce in the ultraviolet region when excited in the ultraviolet region by a shorter wavelength of light, can fluoresce in the visible region when excited by a shorter wavelength of light in the visible region, or can fluoresce in the infrared region when excited by a shorter wavelength of light in the infrared region. The fluorescent semiconductor nanoparticles are often capable of fluorescing in a wavelength range such as, for example, at a wavelength up to 1200 nanometers (nm), or up to 1000 nm, up to 900 nm, or up to 800 nm. For example, the fluorescent semiconductor nanoparticles are often capable of fluorescence in the range of 400 to 800 nanometers.

The nanoparticles have an average particle diameter of at least 0.1 nanometer (nm), or at least 0.5 nm, or at least 1 nm. The nanoparticles have an average particle diameter of up to 1000 nm, or up to 500 nm, or up to 200 nm, or up to 100 nm, or up to 50 nm, or up to 20 nm, or up to 10 nm. Semiconductor nanoparticles, particularly with sizes on the scale of 1-10 nm, have emerged as a category of the most promising advanced materials for cutting-edge technologies.

Semiconductor materials include elements or complexes of Group 2-Group 16,

Group 12-Group 16, Group 13 -Group 15, Group 14-Group 16, and Group 14

semiconductors of the Periodic Table (using the modern group numbering system of 1- 18). Some suitable quantum dots include a metal phosphide, a metal selenide, a metal telluride, or a metal sulfide. Exemplary semiconductor materials include, but are not limited to, Si, Ge, Sn, BN, BP, BAs, AIN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AIN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, MgTe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCI, CuBr, Cul, Si₃N₄, Ge₃N₄, AI2O3, (Ga,In)₂(S,Se,Te)₃, AI2CO, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, and an appropriate combination of two or more such semiconductors. These

semiconductor materials can be used for the core, the one or more shell layers, or both.

In certain embodiments, exemplary metal phosphide quantum dots include indium phosphide and gallium phosphide, exemplary metal selenide quantum dots include cadmium selenide, lead selenide, and zinc selenide, exemplary metal sulfide quantum dots include cadmium sulfide, lead sulfide, and zinc sulfide, and exemplary metal telluride quantum dots include cadmium telluride, lead telluride, and zinc telluride. Other suitable quantum dots include gallium arsenide and indium gallium phosphide. Exemplary semiconductor materials are commercially available from Evident Thermoelectrics (Troy, NY), and from Nanosys Inc., (Mi!pitas, CA).

Nanocrystals (or other nanostructures) for use in the present invention can be produced using any method known to those skilled in the art. Suitable methods are disclosed in U.S. Patent Application No. 10/796,832, filed March 10, 2004, U.S. Patent No. 6,949,206 (Whiteford) and U.S. Provisional Patent Application No. 60/578,236, filed June 8, 2004, the disclosures of each of which are incorporated by reference herein in their entireties. The nanocrystals (or other nanostructures) for use in the present invention can be produced from any suitable material, suitably an inorganic material, and more suitably an inorganic conductive or semiconductive material. Suitable semiconductor materials include those disclosed in U.S. patent application Ser. No. 10/796,832 and include any type of semiconductor, including group II- VI, group III-V, group IV- VI and group IV semiconductors. Suitable semiconductor materials include, but are not limited to, Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AIN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AIN, AlP, As, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, Cul, Si₃N₄, Ge₃N₄, A1₂0₃, (Ga, In)₂(S, Se, Te)₃, Al₂CO, and an appropriate combination of two or more such semiconductors.

In certain aspects, the semiconductor nanocrystals or other nanostructures may comprise a dopant from the group consisting of: a p-type dopant or an n-type dopant. The nanocrystals (or other nanostructures) useful in the present invention can also comprise Group 12-Group 16 or Group 13-Group 15 semiconductors. Examples of Group 12- Group 16 or Group 13-Group 15 semiconductor nanocrystals and nanostructures include any combination of an element from Group 12, such as Zn, Cd and Hg, with any element from Group 16, such as S, Se, Te, Po, of the Periodic Table; and any combination of an element from Group 13, such as B, Al, Ga, In, and Tl, with any element from Group 15, such as N, P, As, Sb and Bi, of the Periodic Table.

Other suitable inorganic nanostructures include metal nanostructures. Suitable metals include, but are not limited to, Ru, Pd, Pt, Ni, W, Ta, Co, Mo, Ir, Re, Rh, Hf, Nb, Au, Ag, Ti, Sn, Zn, Fe, FePt, and the like. While any known method can be used to create nanocrystal phosphors, suitably, a solution-phase colloidal method for controlled growth of inorganic nanomaterial phosphors is used. See Alivisatos, A. P., "Semiconductor clusters, nanocrystals, and quantum dots," Science 271 :933 (1996); X. Peng, M. Schlamp, A. Kadavanich, A. P. Alivisatos, "Epitaxial growth of highly luminescent CdSe/CdS Core/Shell nanocrystals with photostability and electronic accessibility," J. Am. Chem. Soc. 30:7019-7029 (1997); and C. B. Murray, D. J. Norris, M. G. Bawendi, "Synthesis and characterization of nearly monodisperse CdE (E=sulfur, selenium, tellurium) semiconductor nanocrystallites," J. Am. Chem. Soc. 115:8706 (1993). This manufacturing process technology leverages low cost proccessability without the need for clean rooms and expensive manufacturing equipment. In these methods, metal precursors that undergo pyrolysis at high temperature are rapidly injected into a hot solution of organic surfactant molecules. These precursors break apart at elevated temperatures and react to nucleate nanocrystals. After this initial nucleation phase, a growth phase begins by the addition of monomers to the growing crystal. The result is freestanding crystalline nanoparticles in solution that have an organic surfactant molecule coating their surface.

Utilizing this approach, synthesis occurs as an initial nucleation event that takes place over seconds, followed by crystal growth at elevated temperature for several minutes. Parameters such as the temperature, types of surfactants present, precursor materials, and ratios of surfactants to monomers can be modified so as to change the nature and progress of the reaction. The temperature controls the structural phase of the nucleation event, rate of decomposition of precursors, and rate of growth. The organic surfactant molecules mediate both solubility and control of the nanocrystal shape.

In semiconductor nanocrystals, photo-induced emission arises from the band edge states of the nanocrystal. The band-edge emission from nanocrystals competes with radiative and non-radiative decay channels originating from surface electronic states. X. Peng, et al., J. Am. Chem. Soc. 30:7019-7029 (1997). As a result, the presence of surface defects such as dangling bonds provide non-radiative recombination centers and contribute to lowered emission efficiency. An efficient and permanent method to passivate and remove the surface trap states is to epitaxially grow an inorganic shell material on the surface of the nanocrystal. X. Peng, et al., J. Am. Chem. Soc. 30:7019-7029 (1997). The shell material can be chosen such that the electronic levels are type I with respect to the core material (e.g., with a larger bandgap to provide a potential step localizing the electron and hole to the core). As a result, the probability of non-radiative recombination can be reduced. Core-shell structures are obtained by adding organometallic precursors containing the shell materials to a reaction mixture containing the core nanocrystal. In this case, rather than a nucleation-event followed by growth, the cores act as the nuclei, and the shells grow from their surface. The temperature of the reaction is kept low to favor the addition of shell material monomers to the core surface, while preventing independent nucleation of nanocrystals of the shell materials. Surfactants in the reaction mixture are present to direct the controlled growth of shell material and ensure solubility. A uniform and epitaxially grown shell is obtained when there is a low lattice mismatch between the two materials. Additionally, the spherical shape acts to minimize interfacial strain energy from the large radius of curvature, thereby preventing the formation of dislocations that could degrade the optical properties of the nanocrystal system.

In suitable embodiments, ZnS can be used as the shell material using known synthetic processes, resulting in a high-quality emission. As above, if necessary, this material can be easily substituted, e.g., if the core material is modified. Additional exemplary core and shell materials are described herein and/or known in the art.

For many applications of quantum dots, two factors are typically considered in selecting a material. The first factor is the ability to absorb and emit visible light. This consideration makes InP a highly desirable base material. The second factor is the material's photoluminescence efficiency (quantum yield). Generally, Group 12-16 quantum dots (such as cadmium selenide) have higher quantum yield than Group 13-15 quantum dots (such as InP). The quantum yield of InP cores produced previously has been very low (<1 %), and therefore the production of a core/shell structure with InP as the core and another semiconductor compound with higher bandgap (e.g., ZnS) as the shell has been pursued in attempts to improve the quantum yield.

Thus, the fluorescent semiconductor nanoparticles (i.e., quantum dots) of the present disclosure include a core and a shell at least partially surrounding the core. The core/shell nanoparticles can have two distinct layers, a semiconductor or metallic core and a shell surrounding the core of an insulating or semiconductor material. The core often contains a first semiconductor material and the shell often contains a second

semiconductor material that is different than the first semiconductor material. For example, a first Group 12-16 (e.g., CdSe) semiconductor material can be present in the core and a second Group 12-16 (e.g., ZnS) semiconductor material can be present in the shell.

In certain embodiments of the present disclosure, the core includes a metal phosphide (e.g., indium phosphide (InP), gallium phosphide (GaP), aluminum phosphide (A1P)), a metal selenide (e.g., cadmium selenide (CdSe), zinc selenide (ZnSe), magnesium selenide (MgSe)), or a metal telluride (e.g., cadmium telluride (CdTe), zinc telluride (ZnTe)). In certain embodiments, the core includes a metal phosphide (e.g., indium phosphide) or a metal selenide (e.g., cadmium selenide). In certain preferred

embodiments of the present disclosure, the core includes a metal phosphide (e.g., indium phosphide).

The shell can be a single layer or multilayered. In some embodiments, the shell is a multilayered shell. The shell can include any of the core materials described herein. In certain embodiments, the shell material can be a semiconductor material having a higher bandgap energy than the semiconductor core. In other embodiments, suitable shell materials can have good conduction and valence band offset with respect to the semiconductor core, and in some embodiments, the conduction band can be higher and the valence band can be lower than those of the core. For example, in certain embodiments, semiconductor cores that emit energy in the visible region such as, for example, CdS, CdSe, CdTe, ZnSe, ZnTe, GaP, InP, or GaAs, or near IR region such as, for example, InP, InAs, InSb, PbS, or PbSe may be coated with a shell material having a bandgap energy in the ultraviolet regions such as, for example, ZnS, GaN, and magnesium chalcogenides such as MgS, MgSe, and MgTe. In other embodiments, semiconductor cores that emit in the near IR region can be coated with a material having a bandgap energy in the visible region such as CdS or ZnSe.

Formation of the core/shell nanoparticles may be carried out by a variety of methods. Suitable core and shell precursors useful for preparing semiconductor cores are known in the art and can include Group 2 elements, Group 12 elements, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, and salt forms thereof. For example, a first precursor may include metal salt (M+X-) including a metal atom (M+) such as, for example, Zn, Cd, Hg, Mg, Ca, Sr, Ba, Ga, In, Al, Pb, Ge, Si, or in salts and a counter ion (X-), or organometallic species such as, for example, dialkyl metal complexes. The preparation of a coated semiconductor nanocrystal core and core/shell nanocrystals can be found in, for example, Dabbousi et al. (1997) J. Phys. Chem. B 101 :9463, Hines et al. (1996) J. Phys.Chem. 100: 468-471, and Peng et al. (1997) J. Amer. Chem. Soc. 119:7019-7029, as well as in U.S. Pat. No. 8,283,412 (Liu et al.) and

International Publication No. WO 2010/039897 (Tulsky et al.).

In certain preferred embodiments of the present disclosure, the shell includes a metal sulfide (e.g., zinc sulfide or cadmium sulfide). In certain embodiments, the shell includes a zinc-containing compound (e.g., zinc sulfide or zinc selenide). In certain embodiments, a multilayered shell includes an inner shell overcoating the core, wherein the inner shell includes zinc selenide and zinc sulfide. In certain embodiments, a multilayered shell includes an outer shell overcoating the inner shell, wherein the outer shell includes zinc sulfide.

In some embodiments, the core of the shell/core nanoparticle contains a metal phosphide such as indium phosphide, gallium phosphide, or aluminum phosphide. The shell contains zinc sulfide, zinc selenide, or a combination thereof. In some more particular embodiments, the core contains indium phosphide and the shell is multilayered with the inner shell containing both zinc selenide and zinc sulfide and the outer shell containing zinc sulfide.

The thickness of the shell(s) may vary among embodiments and can affect fluorescence wavelength, quantum yield, fluorescence stability, and other photostability characteristics of the nanocrystal. The skilled artisan can select the appropriate thickness to achieve desired properties and may modify the method of making the core/shell nanoparticles to achieve the appropriate thickness of the shell(s).

The diameter of the fluorescent semiconductor nanoparticles (i.e., quantum dots) of the present disclosure can affect the fluorescence wavelength. The diameter of the quantum dot is often directly related to the fluorescence wavelength. For example, cadmium selenide quantum dots having an average particle diameter of about 2 to 3 nanometers tend to fluoresce in the blue or green regions of the visible spectrum while cadmium selenide quantum dots having an average particle diameter of about 8 to 10 nanometers tend to fluoresce in the red region of the visible spectrum.

The quantum dots may be surface modified with ligands of Formula VI:

R¹⁵-R¹²(X)n VI wherein

R¹⁵ is (hetero)hydrocarbyl group having 2 to 30 carbon atoms;

R¹² is a hydrocarbyl group including alkylene, arylene, alkarylene and aralkylene; n is at least one;

X is a ligand group, including -SH, -CO2H, -SO3H, -P(0)(OH)₂, -OP(0)(OH), -

Such additional surface modifying ligands may be added when the functionalizing with the stabilizing additives of Formula VI, or may be attached to the nanoparticles as result of the synthesis. Such additional surface modifying agents are present in amounts less than or equal to the weight of the instant stabilizing additives, preferably lOwt. % or less, relative to the amount of the ligands.

Various methods can be used to surface modify the fluorescent semiconductor nanoparticles with the ligand compounds. In some embodiments, procedures similar to those described in U.S. 7160613 (Bawendi et al.) and 8283412 (Liu et al.) can be used to add the surface modifying agent. For example, the ligand compound and the fluorescent semiconductor nanoparticles can be heated at an elevated temperature (e.g., at least 50°C, at least 60°C, at least 80°C, or at least 90°C) for an extended period of time (e.g., at least 1 hour, at least 5 hours, at least 10 hours, at least 15 hours, or at least 20 hours).

Since InP may be purified by bonding with dodecyl succinic acid (DDSA) and lauric acid (LA) first, following by precipitation from ethanol, the precipitated quantum dots may have some of the acid functional ligands attached thereto, prior to dispersing in the fluid carrier. Similarly, CdSe quantum dots may be functionalized with amine- functional ligands as result of their preparation, prior to functionalization with the instant ligands. As a result, the quantum dots may be functionalized with those surface modifying additives or ligands resulting from the original synthesis of the nanoparticles.

If desired, any by-product of the synthesis process or any solvent used in surface- modification process can be removed, for example, by distillation, rotary evaporation, or by precipitation of the nanoparticles and centrifugation of the mixture followed by decanting the liquid and leaving behind the surface-modified nanoparticles. In some embodiments, the surface-modified fluorescent semiconductor nanoparticles are dried to a powder after surface-modification. In other embodiments, the solvent used for the surface modification is compatible (i.e., miscible) with any carrier fluids used in compositions in which the nanoparticles are included. In these embodiments, at least a portion of the solvent used for the surface-modification reaction can be included in the carrier fluid in which the surface-modified, fluorescent semiconductor nanoparticles are dispersed.

The fluorescent semiconductor nanoparticles may be dispersed in a solution that contains (a) an optional carrier fluid and (b) the polymeric binder, a precursor of the polymeric binder, or combinations thereof (i.e. the epoxy-amine resin and the radiation curable resin described herein). The nanoparticles may be dispersed in the polymeric or non-polymeric carrier fluid, which is then dispersed in the polymeric binder, forming droplets of the nanoparticles in the carrier fluid, which in turn are dispersed in the polymeric binder. The carrier fluids are typically selected to be compatible (i.e., miscible) with the stabilizing additive (if any) and surface modifying ligand of the fluorescent semiconductor nanoparticles.

Suitable carrier fluids include, but are not limited to, aromatic hydrocarbons (e.g., toluene, benzene, or xylene), aliphatic hydrocarbons such as alkanes (e.g., cyclohexane, heptane, hexane, or octane), alcohols (e.g., methanol, ethanol, isopropanol, or butanol), ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone), aldehydes, amines, amides, esters (e.g., amyl acetate, ethylene carbonate, propylene carbonate, or methoxypropyl acetate), glycols (e.g., ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, diethylene glycol, hexylene glycol, or glycol ethers such as those commercially available from Dow Chemical, Midland, MI under the trade designation DOWANOL), ethers (e.g., diethyl ether), dimethyl sulfoxide,

tetram ethyl sulfone, halocarbons (e.g., methylene chloride, chloroform, or

hydrofluoroethers), or combinations thereof. Preferred carrier fluids include aromatic hydrocarbons (for e.g., toluene), aliphatic hydrocarbons such as alkanes.

The optional non-polymeric carrier fluids are inert, liquid at 25°C and have a boiling point >100°C, preferably >150°C; and can be one or a mixture of liquid compounds. Higher boiling points are preferred so that the carrier fluids remain when organic solvents used in the preparation are removed.

In some embodiments the carrier fluid is an oligomeric or polymeric carrier fluid. The polymeric carriers provide a medium of intermediate viscosity that is desirable for further processing of the additive in combination with the fluorescent nanoparticle into a thin film. The polymeric carrier is preferably selected to form a homogenous dispersion with the additive combined fluorescent nanoparticle, but preferably incompatible with the curable polymeric binders. The polymeric carriers are liquid at 25°C and include polysiloxanes, such a polydimethylsiloxane, liquid fluorinated polymers, including perfluoropolyethers, (poly(acrylates), polyethers, such as poly(ethylene glycol), poly(propylene glycol), and poly(butylene glycol). A preferred polymeric polysiloxane is polydimethylsiloxane.

Aminosilicone carrier fluids are preferred for CdSe quantum dots, and can also serve as stabilizing ligands. Useful aminosilicones, and method of making the same, are described in US 2013/0345458 (Freeman et al.), incorporated herein by reference. Useful amine-functional silicones are described in Lubkowsha et al., Aminoalkyl Functionalized Siloxanes, Polimery, 2014 59, pp 763-768, and are available from Gelest Inc, Morrisville, PA, from Dow Corning under the Xiameter^tm, including Xiamter OFX-0479, OFX-8040, OFX-8166, OFX-8220, OFX-8417, OFX-8630, OFX-8803, and OFX-8822. Useful amine-functional silicones are also available from Siletech.com under the tradenames Silamine¹™, and from Momentive.com under the tradenames ASF3830, SF4901,

Magnasoft, Magnasoft PlusTSF4709, Baysilone OF-TP3309, RPS-116, XF40-C3029 and TSF4707

Desirably, the liquid carrier is chosen to match the transmissivity of the polymer matrix. To increase the optical path length through the quantum dot layer and improve quantum dot absorption and efficiency, the difference in the refractive indices of the carrier liquid and the polymer matrix is > 0.05, preferably > 0.1. In some embodiments the amount of ligand and carrier liquid (ligand functional or non-functional) is > 60 wt.%, preferably >70 wt.%, more preferably >80 wt.%, relative to the total including the inorganic nanoparticles.

Referring to FIG. 1, quantum dot article 10 includes a first barrier layer 32, a second barrier layer 34, and a quantum dot layer 20 between the first barrier layer 32 and the second barrier layer 34. The quantum dot layer 20 includes a plurality of quantum dots 22 dispersed in the polymeric binder 24 (described herein), which may be cured or uncured.

The quantum dot layer can have any useful amount of quantum dots. In some embodiments, the quantum dots are added to the fluid carrier in amounts such that the optical density is at least 10, optical density defined as the absorbance at 440nm for a cell with a path length of 1 cm) solution.

The barrier layers 32, 34 can be formed of any useful material that can protect the quantum dots 22 from exposure to environmental contaminates such as, for example, oxygen, water, and water vapor. Suitable barrier layers 32, 34 include, but are not limited to, films of polymers, glass and dielectric materials. In some embodiments, suitable materials for the barrier layers 32, 34 include, for example, polymers such as polyethylene terephthalate (PET); oxides such as silicon oxide, titanium oxide, or aluminum oxide (e.g., S1O2, S12O3, T1O2, or AI2O3); and suitable combinations thereof.

More particularly, barrier films can be selected from a variety of constructions.

Barrier films are typically selected such that they have oxygen and water transmission rates at a specified level as required by the application. In some embodiments, the barrier film has a water vapor transmission rate (WVTR) less than about 0.005 g/m²/day at 38°C. and 100% relative humidity; in some embodiments, less than about 0.0005 g/m²/day at 38°C. and 100% relative humidity; and in some embodiments, less than about 0.00005 g/m²/day at 38°C and 100% relative humidity. In some embodiments, the flexible barrier film has a WVTR of less than about 0.05, 0.005, 0.0005, or 0.00005 g/m²/day at 50 °C and 100% relative humidity or even less than about 0.005, 0.0005, 0.00005 g/m²/day at 85 °C and 100%) relative humidity. In some embodiments, the barrier film has an oxygen transmission rate of less than about 0.005 g/m²/day at 23°C and 90% relative humidity; in some embodiments, less than about 0.0005 g/m²/day at 23 °C and 90% relative humidity; and in some embodiments, less than about 0.00005 g/m²/day at 23 °C and 90% relative humidity.

Exemplary useful barrier films include inorganic films prepared by atomic layer deposition, thermal evaporation, sputtering, and chemical vapor deposition. Useful barrier films are typically flexible and transparent. In some embodiments, useful barrier films comprise inorganic/organic. Flexible ultra-barrier films comprising inorganic/organic multilayers are described, for example, in U.S. 7,018,713 (Padiyath et al.). Such flexible ultra-barrier films may have a first polymer layer disposed on polymeric film substrate that is overcoated with two or more inorganic barrier layers separated by at least one second polymer layer. In some embodiments, the barrier film comprises one inorganic barrier layer interposed between the first polymer layer disposed on the polymeric film substrate and a second polymer layer 224 as shown in Figure 3.

In some embodiments, each barrier layer 32, 34 of the quantum dot article 10 includes at least two sub-layers of different materials or compositions. In some embodiments, such a multi-layered barrier construction can more effectively reduce or eliminate pinhole defect alignment in the barrier layers 32, 34, providing a more effective shield against oxygen and moisture penetration into the cured polymeric binder 24. The quantum dot article 10 can include any suitable material or combination of barrier materials and any suitable number of barrier layers or sub-layers on either or both sides of the quantum dot layer 20. The materials, thickness, and number of barrier layers and sublayers will depend on the particular application, and will suitably be chosen to maximize barrier protection and brightness of the quantum dots 22 while minimizing the thickness of the quantum dot article 10. In some embodiments each barrier layer 32, 34 is itself a laminate film, such as a dual laminate film, where each barrier film layer is sufficiently thick to eliminate wrinkling in roll-to-roll or laminate manufacturing processes. In one illustrative embodiment, the barrier layers 32, 34 are polyester films (e.g., PET) having an oxide layer on an exposed surface thereof.

The quantum dot layer 20 can include one or more populations of quantum dots or quantum dot materials 22. Exemplary quantum dots or quantum dot materials 22 emit green light and red light upon down-conversion of blue primary light from a blue LED to secondary light emitted by the quantum dots. The respective portions of red, green, and blue light can be controlled to achieve a desired white point for the white light emitted by a display device incorporating the quantum dot article 10. Exemplary quantum dots 22 for use in the quantum dot articles 10 include, but are not limited to, InP with ZnS shells. Suitable quantum dots for use in quantum dot articles described herein include, but are not limited to, core/shell fluorescent nanocrystals including CdSe/ZnS, InP/ZnS, PbSe/PbS, CdSe/CdS, CdTe/CdS or CdTe/ZnS.

In exemplary embodiments, the nanoparticles include a ligand, a fluid carrier and are dispersed in the cured or uncured polymeric binder. Quantum dot and quantum dot materials 22 are commercially available from, for example, Nanosys Inc., Milpitas, CA.

In one or more embodiments the quantum dot layer 20 can optionally include scattering beads or particles. These scattering beads or particles have a refractive index that differs from the refractive index of the cured polymeric binder 24 by at least 0.05, or by at least 0.1. These scattering beads or particles can include, for example, polymers such as silicone, acrylic, nylon, and the like, or inorganic materials such as T1O2, SiOx, AlOx, and the like, and combinations thereof. In some embodiments, including scattering particles in the quantum dot layer 20 can increase the optical path length through the quantum dot layer 20 and improve quantum dot absorption and efficiency. In many embodiments, the scattering beads or particles have an average particle size from 1 to 10 micrometers, or from 2 to 6 micrometers. In some embodiments, the quantum dot material 20 can optionally include fillers such fumed silica.

In some preferred embodiments, the scattering beads or particles are TOSPEARL

120A, 130A, 145A and 2000B spherical silicone resins available in 2.0, 3.0, 4.5 and 6.0 micron particle sizes respectively from Momentive Performance Materials, Waterford, NY.

The cured polymeric binder 24 of the quantum dot layer 20 can be formed from a polymeric binder or binder precursor that adheres to the materials forming the barrier layers 32, 34 to form a laminate construction, and also forms a protective matrix for the quantum dots 22. In one embodiment, the cured polymeric binder 24 is formed by curing an epoxy amine polymer and an optional radiation-curable methacrylate compound.

Referring to FIG. 2, in another aspect, the present disclosure is directed to a method of forming a quantum dot film article 100 including coating the curable composition including quantum dots on a first barrier layer 102 and disposing a second barrier layer on the quantum dot material 104. In some embodiments, the method 100 includes polymerizing (e.g., radiation curing) the radiation curable methacrylate compound to form a partially cured quantum dot material 106 and polymerizing (e.g., thermal curing) the epoxide and the amino-functional curing agent of the partially cured quantum dot material to form a cured matrix 108.

The curable composition can be cured or hardened by applying radiation such as ultraviolet (UV) or visible light to cure the radiation curable component, followed by heating to cure the thermally curable component. In some example embodiments UV cure conditions can include applying about 10 mJ/cm² to about 4000 mJ/cm² of UVA, more preferably about 10mJ/cm² to about 200 mJ/cm² of UVA. Heating and UV light may also be applied alone or in combination to increase the viscosity of the curable composition, which can allow easier handling on coating and processing lines.

In some embodiments, the curable composition may be cured after lamination between the overlying barrier films 32, 34. Thus, the increase in viscosity of the curable composition locks in the coating quality right after lamination. By curing right after coating or laminating, in some embodiments the cured methacrylate polymer increases the viscosity of the curable composition to a point that the curable composition acts as a pressure sensitive adhesive (PSA) to hold the laminate together during the thermal cure of the epoxy amine and greatly reduces defects during a cure of the epoxy amine. In some embodiments, the radiation cure of the resorcinol methacrylate of the curable composition provides greater control over coating, curing and web handling as compared to traditional thermal curing of an epoxy only curable composition.

Once at least partially cured, the curable composition forms an interpenetrating polymer network that provides a protective supporting matrix 24 for the quantum dots 22. In this application the term interpenetrating polymer network refers to a combination of two or more polymers in network form that are synthesized in juxtaposition. In various embodiments, the cured supporting matrix 24 includes about 70 wt% to about 100 wt%, about 70 wt% to about 90 wt%, or about 75 wt% to about 85 wt%, of the epoxy amine polymer. In various embodiments, the cured supporting matrix 24 includes about 0 wt% to about 25 wt%, about 5 wt% to about 25 wt%, or about 10 wt% to about 20 wt%, of the methacrylate polymer.

In various embodiments, the color change observed upon aging is defined by a change of less than 0.02 on the 1931 CIE (x,y) Chromaticity coordinate system following an aging period of 1 week at 85°C. In certain embodiments, the color change upon aging is less than 0.005 on the following an aging period of 1 week at 85°C.

In various embodiments, the thickness of the quantum dot layer 20 is about 40 microns to about 400 microns, or about 80 microns to about 250 microns.

FIG 3 is a schematic illustration of an embodiment of a display device 200 including the quantum dot articles described herein. This illustration is merely provided as an example and is not intended to be limiting. The display device 200 includes a backlight 202 with a light source 204 such as, for example, a light emitting diode (LED). The light source 204 emits light along an emission axis 235. The light source 204 (for example, a LED light source) emits light through an input edge 208 into a hollow light recycling cavity 210 having a back reflector 212 thereon. The back reflector 212 can be predominately specular, diffuse or a combination thereof, and is preferably highly reflective. The backlight 202 further includes a quantum dot article 220, which includes a protective matrix 224 having dispersed therein quantum dots 222. The protective matrix 224 is bounded on both surfaces by polymeric barrier films 226, 228, which may include a single layer or multiple layers.

The display device 200 further includes a front reflector 230 that includes multiple directional recycling films or layers, which are optical films with a surface structure that redirects off-axis light in a direction closer to the axis of the display, which can increase the amount of light propagating on-axis through the display device, this increasing the brightness and contrast of the image seen by a viewer. The front reflector 230 can also include other types of optical films such as polarizers. In one non-limiting example, the front reflector 230 can include one or more prismatic films 232 and/or gain diffusers. The prismatic films 232 may have prisms elongated along an axis, which may be oriented parallel or perpendicular to an emission axis 235 of the light source 204. In some embodiments, the prism axes of the prismatic films may be crossed. The front reflector 230 may further include one or more polarizing films 234, which may include multilayer optical polarizing films, diffusely reflecting polarizing films, and the like. The light emitted by the front reflector 230 enters a liquid crystal (LC) panel 280. Numerous examples of backlighting structures and films may be found in, for example, U.S. 8848132 (O'Neill et al.).

EXAMPLES

TABLE 1. Materials

Quantum Dots Nanosys as "Part# QCEF52035R2" CA

Red CdSe Red CdSe Quantum Dots available from Nanosys, Palo Alto, Quantum Dots Nanosys as "Part# QCEF62290P3-01" CA

EPON 862 a diglycidyl ether of bisphenol-F available as Hexion, Columbus, OH

"EPON 862"

EX201 resorcinol digylcidyl ether, available as ΈΧ- Nagase America Corp.,

201" New York, NY

TDD 4,7, 10-trioxatridecanediamine, available from BASF, Florham Park,

BASF under the trade designation NJ

"BAXXODUR EC 130"

TCD 3 (or 4), 8(or 9)- OXEA Corp., Dallas, diaminomethyltricyclo(5,2, 1,0^{2 6}) decane) TX

TCD-diol 3 (or 4), 8(or 9)- OXEA Corp., Dallas, bis(hydroxymethyl)tricycle(5.2.1.0^{2 <5})decane TX

DM-201 a dimethacrylate resin based on resorcinol Nagase America Corp., diglycidyl ether, available as "DM-201" New York, NY

RE DM a dimethacrylate resin based on resorcinol DKSH North America, diglycidyl ether, available as "REDM" Inc., Mount Arlington,

NJ

DAROCUR A liquid free-radical photoinitiator, available BASF, Florham Park,

4265 as "DAROCUR 4265" NJ

RDGE resorcinol diglycidyl ether, available under CVC Thermoset,

the trade designation "RDGE" Moore stown, NJ

AMBERLITE Anion exchange resin available under the Sigma-Aldrich, St. IRA-900C1 trade designation "AMBERLITE IRA- Louis, MO

900C1"

Methacrylic acid Sigma-Aldrich, St.

Louis, MO

PRO STAB 4-hydroxy-2,2,6,6-tetramethyl- 1 - BASF, Florham Park, 5198 piperidinyloxy, an N-oxide polymerization NJ

inhibitor available under the trade designation "PROSTAB 5198"

Measurements

For each constructed QDEF film sample, the white point (color) and luminance (brightness) were quantified by placing the constructed QDEF film 310 into a recycling system 300 (FIG. 4) and measuring with a SPECTRASCANPR-650

SPECTRACOLORIMETER 302 with an MS-75 lens, available from Photo Research, Inc., Chatsworth, Calif. The constructed QDEF film 310 was placed on top of a diffusely transmissive hollow light box 304. The diffuse transmission and reflection of the light box 304 can be described as Lambertian. Light box 304 was a six-sided hollow cube measuring approximately 12.5 cm x 12.5 cm x 11.5 cm (L x W x H) made from diffuse PTFE plates of ~6 mm thickness. One face of hollow light box 304 was chosen as the sample surface. Hollow light box 304 had a diffuse reflectance of -0.83 measured at the sample surface (e.g. -83%, averaged over the 400-700 nm wavelength range).

The hollow light box 304 was illuminated from within by a blue LED light source (-450 nm). The sample color and luminance was measured with the PR-650 at normal incidence to the plane of the box sample surface when the sample films are placed parallel to the box sample surface, the sample films being in general contact with the box.

Two pieces of micro-replicated brightness enhancement film 308 (available from 3M Co., St. Paul, MN, under the trade designation "3M BEF") were placed in a 90 degree crossed configuration above constructed QDEF film 310. The entire measurement was carried out in a black enclosure to eliminate stray light sources. A white point and luminance value, in units of candela per meter square, was measured for each film sample in this recycling system.

Coatings were typically were tested initially, after 24 hours, and after 1, 2, 3, and 4 weeks of aging in a lifetime screening box (aged at a temperature of 85°C and a light intensity of 152 watts/steradian/m^).

Measurement of luminance over time was performed in an accelerated aging test, using an in-house designed lifetime screening box. The lifetime test box is small light box containing an array of blue LEDs having a peak wavelength of about 450 nm, and an output intensity of the 152 watts per steradian. A ground glass diffuser was placed over the LEDs to improve the illumination uniformity. For lifetime aging of the samples, a round sample (approximately 1.9 cm diameter) of each film was placed directly above the glass diffuser. A metal reflector is then placed over the samples to simulate recycling in a typical LED backlight. The sample temperature was controlled to approximately 85°C with air flow and heat sinks. To eliminate sample to sample variations of white point and thickness, normalized luminance (relative to the as-coated measurement) of each sample was used when evaluating luminance over time. Enhanced luminance is defined as the ability of the quantum dot containing films to maintain a high normalized luminance while being illuminated over time. The films were tested at five time intervals: immediately after coating, after 24 hours, and after one, two, and four weeks in the lifetime screening box. Results from the measurements are shown in the data tables in the examples.

Preparative Example 1 : TTD-TCD-EX201

TTD-TCD-EX201 is a diamine that was prepared by blending TTD (51 parts by weight) and TCD (17 parts by weight) in a round bottom flask, heating to 50°C in an oil bath, and adding EX201 (22.4 parts by weight) slowly such that the reaction temperature did not exceed 130°C. The mixture was allowed to cool and then held at 50°C for 60 minutes after the peak reaction temperature was reached. The resulting pale yellow liquid was used as is.

Preparative Example 2: TTD-TCD-EPON862

TTD-TCD-EPON862 is a diamine that was prepared in a similar fashion to the TTD-TCD-EX-201 diamine, but by blending TTD (51 parts by weight), TCD (17 parts by weight), and EPON 862 (32 parts by weight) and maintaining about 55 mbar vacuum throughout the reaction. The resulting pale yellow liquid was used as is.

Preparative Example 3 : TCD extended REDM

To a round bottom flask was added TCD diol (37.3 g), succinic anhydride (40.0 g), trimethylamine (0.12 g) and toluene (70 g). The resulting mixture was heated to 100°C for about 16 hours. To the resulting material was added RDGE-H (a high purity resorcinoi epoxy resin, available from CVC Thermoset, Moorestown, NJ, 138.5 g) and

AMBERLITE IRA-900C1 resin (4.3 g). The mixture was heated to 100°C for about 16 hours. The mixture was filtered and divided into two portions. To one of the portions of the resulting mixture was added methacrylic acid (36.0 g), AMBERLITE IRA-900C1 resin (2.0 g) and 4-hydroxy-TEMPO (also referred to as PROSTAB 5198, 18 mg). The mixture was heated to 100°C for 6 hours. The mixture was filtered and toluene was removed by distillation under reduced pressure on a rotary evaporator.

Preparative Example 4: Preparation of REDM

To a round bottom flask was added resorcinol diglycidyl ether ("RDGE-H", from CVC Thermoset, Moorestown, NJ, 85.6 g), methacrylic acid (70 g), 4-hydroxy-TEMPO (also referred to as PROSTAB 5198, 0.042 g) and Amberlite IRA-900C1 resin (from Dow, 3.26 g). The mixture was heated to 100 °C for about 21 hours. The mixture was filtered to provide the product.

Preparative Example 5: White dot concentrate (Solution A)

A white dot concentrate (Solution A) was prepared using CdSe quantum dots as received from Nanosys Inc., as shown in Table 2.

TABLE 2: Solution A - White CdSe Quantum Dot Concentrate

Examples 1-6 (EX1 to EX6) and Comparative Example C1-C2:

For each Example and Comparative Example, the epoxy, (meth)acrylate, and photoinitiator were combined in a 4 ounce (125 ml) amber glass jar, heated to 70°C and hand stirred using a wooden applicator stick to ensure mixing. The resulting mixture was degassed under vacuum and transferred to a glovebox where the appropriate amount of Solution A and amine were added. Table 3 shows the components and amounts used for these examples. The resulting mixture was stirred using a 1 inch (25mm) stainless steel impeller blade attached to a mechanical stirrer at 1400 rpm for 4 minutes. The resulting formulation was hand-coated between two sheets of 2 mil (51 micrometer) thick barrier film (available as "3M FTB3" from 3M Company, St. Paul MN), at a thickness of 100 micrometers using a knife-coater. Immediately after coating, the film was irradiated using a 385 nm LED (MODEL CF2000, Clearstone Technologies, Hopkins, MN) for 30 seconds at 50% power, at a distance of approximately 1 inch (25 mm). Subsequent thermal cure was performed at 100°C for either 10 minutes (Examples CI and Examples 1-3) or 20 minutes (Examples C2 and Examples 4-6) to give QDEF articles that were tested under light illumination conditions.

Table 4 shows the luminance data (normalized to the initial luminance) for Comparative Example CI and Examples 1-3, which were thermally cured at 120°C for 10 minutes. The data shows a higher luminance of all three resorcinol-containing samples (Examples 1-3) when compared to the Comparative example CI, which did not contain resorcinol-based materials.

Table 5 shows the white point measurements for Comparative Example CI and Examples 1-3, which were thermally cured at 120°C for 10 minutes.

Table 6 shows the luminance data (normalized to the initial luminance) for Comparative Example C2 and Examples 4-6, which were thermally cured at 120°C for 20 minutes. The data showed the higher luminance of all three resorcinol-containing samples (Examples 4-6) when compared to the comparative example C2 that did not contain resorcinol-based materials.

Table 7 shows the white point measurements for Comparative Example C2 and Examples 4-6, which were thermally cured at 120°C for 20 minutes.

Examples 7-12 and Comparative Example C3-C4:

The QDEF films for Comparative Examples C3-C4 and Examples 7-12 were prepared as described for Examples 1-6. Table 8 shows the components and amounts used for these examples. The "REDM" material used in these examples was that obtained from DKSH North America, Inc. (Mount Arlington, NJ).

Table 9 shows the luminance data (normalized to the initial luminance) for Comparative Example C3 and Examples 7-9, which were thermally cured at 120°C for 10 minutes.

Table 10 shows the white point measurements for Comparative Example C3 and Examples 7-9, which were thermally cured at 120°C for 10 minutes. Table 11 shows the luminance data (normalized to the initial luminance) for Comparative Example C4 and Examples 10-12, which were thermally cured at 120°C for 20 minutes.

Table 12 shows the white point measurements for Comparative Example C4 and Examples 10-12, which were thermally cured at 120°C for 20 minutes.

TABLE 3. Formulations with various Epoxy: Amine Ratios

TABLE 4. Normalized Luminance Measurements - Cured at 120°C for 10 minutes

TABLE 5. White Point Measurements - Cured at 120°C for 10 minutes

TABLE 6. Normalized Luminance Measurements - Cured at 120°C for 20 minutes

TABLE 7. White Point Measurements - Cured at 120°C for 20 minutes

TABLE 8. Formulations with various Epoxy:Amine Ratios

TABLE 9. Normalized Luminance Measurements - Cured at 120°C for 10 minutes

TABLE 10. White Point Measurements - Cured at 120°C for 10 minutes

TABLE 11. Normalized Luminance Measurements - Cured at 120°C for 20 minutes

TABLE 12. White Point Measurements - Cured at 120°C for 20 minutes

Claims

What is claimed is:

A composition comprising core-shell quantum dots dispersed in a curable composition comprising:

a) a thermally curable component comprising a polyepoxide and a polyamine; and b) a free radically curable component comprising a resorcinol dimethacrylate compound.

The composition of claim 1, wherein the curable composition comprises 50 to 95 wt.% of the thermally curable component and 5 to 50 wt.% of the free radically curable component.

The composition of claim 1 wherein the resorcinol dimethacrylate compound is of the formula:

wherein

R¹ is CH₃,

R¹⁰ is a (hetero)hydrocarbyl group;

R¹¹ is a (hetero)hydrocarbyl group.

4. The composition of claim 3 wherein R¹⁰ is -CH₂-CH(OH)-CH₂-.

5. The composition of claim 3 wherein R¹¹ comprises a cyclic or poly cyclic aliphatic group.

6. The composition of claim 1 wherein the polyepoxide is a resorcinol diglycidyl ether.

7. The curable composition of claim 1 wherein the polyamine is of the formula H2N— CnH2n— A— CmH2m— H2, wherein

A is an acyclic, monocyclic or a polycyclic alkylene group, or an acyclic, monocylic or a polycyclic heteroalkylene group, and m and n are integers each independently selected from 0 to 5.

8. The curable composition of claim 1 wherein the polyamine is selected from 3(or 4), 8(or 9)-diaminomethyltricyclo(5,2, l,0^{2 6}) decane; 4,9(or 10)- diaminomethyltetracyclo(6,2, l,l^{3 6},0^{2 7}) dodecane; or 2,5(or 6)-diaminomethyl bicyclo(2,2,l)heptane.

9. The composition of claim 1 wherein the radiation-curable component comprises a monofunctional (meth)acrylate monomer.

10. The composition of claim 1 wherein the radiation-curable component comprises a polyfunctional methacrylate monomer or oligomer.

11. The composition of claim 1 where the resorcinol dimethacrylate is > 50 wt%, of the radiation-curable component of the curable composition.

12. The composition of claim 1 wherein the molar ratio of epoxy groups to amine groups in the thermally curable component is about 0.6 to about 1.4 moles epoxy to moles amine.

13. The composition of claim 1 further comprising a photoinitiator.

14. The composition of claim 1 comprising 5 to 30 wt.% of the radiation-curable component and 70 to 95 wt% of the thermally-curable component.

15. The composition of claim 1 further comprising scattering particles having an average size in a range from 1 to 10 micrometers. The composition of claim 3, wherein R¹¹ comprises a monocyclic or a polycyclic alkylene group, or a monocylic or a polycyclic heteroalkylene group.

17. The composition of claim 1 wherein the quantum dots are dispersed in a carrier

18. The composition of claim 1 wherein the quantum dots are ligand functionalized with ligands of the formula:

R¹⁵-R¹²(X)n

wherein

R¹⁵ is (hetero)hydrocarbyl group having 2 to 30 carbon atoms;

R¹² is a hydrocarbyl group including alkylene, arylene, alkarylene and aralkylene; n is at least one; and

X is a ligand group, including -SH, -CO2H, -SO3H, -P(0)(OH)₂, -OP(0)(OH), -

19. The composition of claim 1, wherein the epoxy of the epoxy-amine resin is a glycidyl ether of the formula:

where R is (hetero)hydrocarbyl group containing at having a valence of m, and m is > 2.

20. The composition of claim 3 wherein Rl 1 is a polyester. 21. The composition of claim 1 wherein the polyamine is of the formula: R⁵⁰-( HR⁵¹)b, wherein

R⁵⁰ is a monovalent, divalent or trivalent polyether radical having at least 2 groups of formula-(R⁵²-0)-, where R⁵² is a linear or branched alkylene having 1 to 4 carbon atoms, R⁵¹ is hydrogen or alkyl and subscript b is equal to lto 3.

22. The composition of claim 1 wherein the polyamine is of the formula: H₂N-R⁵⁵-(OR⁵⁶)d- H₂, wherein

each group R⁵⁵ and R⁵⁶ is each independently a branched or linear alkylene having 1 to 4 carbon atoms and subscript d is equal to at least 2.

23. The composition of claim 1 wherein the quantum dots are CdSe or InP quantum dots, ligand functionalized with an aminosilicone carrier fluid.

24. The composition of claim 23 wherein the CdSe quantum dots are core-shell with a core of CdSe and a shell of ZnS.

25. The composition of claim 24 wherein the shell is a multilayered shell comprising an inner shell of zinc selenide or zinc sulfide and an outer shell of ZnS or MgS.

26. The composition of claim 25 wherein the weight ratio of quantum dots the curable composition is 0.1% to 20%.

27. A quantum dot film article comprising:

a first barrier layer;

a second barrier layer; and

a quantum dot layer between the first barrier layer and the second barrier layer, the quantum dot layer comprising quantum dots dispersed in a polymermatrix comprising an interpenetrating polymer network of

c) a thermally cured epoxy-amine resin; and

d) a free radically cured resorcinol dimethacrylate.

28. The film article of claim 27, wherein the quantum dots are ligand functionalized.

29. The film article of claim 27 wherein the quantum dots are dispersed in a carrier fluid forming droplets, the droplets dispersed in the polymer matrix.

30. The film article of claim 27 wherein the quantum dots are selected from CdSe/ZnS and InP/ZnS.

31. The article of any of claims 27-30, wherein the weight ratio of quantum dots in matrix is 0.1% to 20%.

32. The article of any of claims 27-31 further comprising primer layers disposed

between the barrier layers and the quantum dot layer.

33. The article of any of claims 27-32 further comprising no primer layers disposed between the barrier layers and the quantum dot layer.

34. The article of any of the previous claims 27-33 wherein the matrix has an average transmissivity of at least 85% in the region of 450 to 750 nm.

35. The film article of any of claims 27-34, wherein the matrix further comprises scattering particles having an average size in a range from 1 to 10 micrometers.

36. The film article of any of claims 27-35, wherein at least one of the first and the second barrier layer comprises at least one polymeric film.

37. The film article of any of claims 27-36, having an external quantum efficiency ( EQE) > 85%.

38. The article of any of claims 27-37, wherein the thickness of the quantum dots matrix layer between the first and second barrier layers is 25 to 500 um.

39. A display device comprising the film article of any one of claims 27-38.