Holographic recording material and method for producing the same

Abstract

Provided herein are compositions suitable for recording holograms that include thiol and / or thioether functional groups, and optionally include additional allyl and / or propargyl functional groups. These monomers can be used to synthesize holographic polymers with high Δn values. Also provided herein are methods of making holographic polymers and methods of recording holograms using these polymers.

Description

[0001] Cross-reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 037,296, filed June 10, 2020, entitled “HOLOGRAPHIC RECORDING MATERIALS AND METHODS OF MAKING SAME,” the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND

[0003] Holographic photopolymers are a class of materials platform of interest and are required for applications including, among others, see-through displays, data storage, and diffractive optical elements, because these polymers have ease of processing and single-step recording capability. For all these applications, a key performance specification that is directly related to device quality and performance is the achievable index modulation (An). Work to improve index modulation has focused on enhancing the index contrast between the written monomer and the matrix, while maintaining high monomer solubility, which enables high written monomer loadings in non-phase-segregated polymers.

[0004] There is a need in the art for new holographic recording materials and methods of making the same. The present invention addresses this need. SUMMARY

[0005] In various embodiments, compositions are provided. In certain embodiments, the composition includes:

[0006] at least one polymer;

[0007] a polymeric binder comprising a plurality of allyl groups; and

[0008] at least one monomer of Formula (I):

[0009]

[0010] and at least one monomer of Formula (II):

[0011]

[0012] wherein:

[0013] each occurrence of X is independently H or an optionally substituted C 6-14 aryl group;

[0014] each Y is independently -S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, -CH(SH)-, -CH[O-CH2-CH=CH2]-, or -CH[O-CH2-CºCH]-;

[0015] each Y T is independently H, -SH, -CH=CH2, -CºCH, or optionally substituted C 6-14 aryl;

[0016] each Z is independently -S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, or -CH(SH)-;

[0017] each Z T is independently H, -SH, or -CH2SH;

[0018] m is an integer in the range of 0 to 100; and

[0019] n is an integer in the range of 0 to 100.

[0020] Advantageously, in various embodiments, the composition can be used to form a holographic material. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings generally illustrate various embodiments of the application, which are not to be construed as limiting.

[0022] Figures 1A-1D A schematic example of holographic film preparation and hologram formation is shown. Figure 1A A formulation of a writing monomer and linear binder with pendant allyl side chains is shown. Figure 1B Hologram formation and flood curing is shown. Figure 1C A formulation of an alcohol-isocyanate linear binder is shown. Figure 1D A photograph of a general hologram taken under illumination of a front right PC monitor. The formulation used contained 43 w% thiol-ene writing monomer and 30 mol% allyl in the binder.

[0023] Figures 2A-2D Hologram performance in terms of dynamic range (Δn) is shown. Figure 2A Angular playback spectrum of a representative hologram is shown, showing very good agreement with the Kogelnik equation. (Holographic pitch Λ = 1 μm; this formulation has 30 mol% allyl and 43 w% thiol-ene).Figure 2B The dynamic range of holograms of thiol-ene writing monomers with different loadings is shown at a spacing of Λ = 0.5 μm. Figure 2C The effect of the grating period on the dynamic range of various components is shown. Figure 2D Atomic force microscopy (AFM) images of a sample containing 20 w% thiol-ene writing monomers and 30 mol% allyl groups in a polymer binder are shown.

[0024] Figure 3 The spectrum of the recorded reflection hologram is shown (30 mol% allyl and 43 w% thiol-ene writing monomers in polymer binder).

[0025] Figure 4 The graph shows the diffraction efficiency (DE) vs. development over time (43 wt% thiol-olefin monomer and 30 mol% allyl).

[0026] Figure 5 Showing Figure 4 The same holographic recording membrane is characterized by its profile.

[0027] Figure 6 The outline characterization of the thick holographic film used to record the reflection hologram is shown.

[0028] Figures 7A-7B The dynamic range of the transmission hologram recorded with a spacing of 1 μm is shown. Figure 7A The dynamic range of holograms of thiol-ene writing monomers with different loadings is shown. Figure 7B This shows the effect of allyl content on the dynamic range of various components.

[0029] Figures 8A-8B The effect of grating period on the dynamic range of various components is illustrated (where Λ is the spatial period). Figure 8A The effect of 20 w% thiol-ene writing monomer loading is shown. Figure 8B The effect of 33 w% thiol-ene writing monomer loading is shown.

[0030] Figures 9A-9B Examples of thiol-olefin holograms at 0.5 μm ( Figure 9A ) or 1μm ( Figure 9B The tunability of the dynamic range under different spacing sizes.

[0031] Figure 10 GPC (gel permeation chromatography) curves of linear matrices with different allyl contents are displayed.

[0032] Figure 11An optical layout for transmission hologram exposure and replay is illustrated. Component labels: L1, 633 nm He-Ne laser; L2, 405 nm diode laser; M, mirror; D, power detector; HW, half waveplate; HF, holographic film; PBS, polarizing beam splitter; S, rotatable stage.

[0033] Figure 12 An optical layout for reflection hologram exposure is illustrated. Component labels: L1, 633 nm He-Ne laser; M, mirror; D, power detector; HW, half waveplate; HF, holographic film; PBS, polarizing beam splitter; S, rotatable stage.

[0034] Figures 13A-13B AFM image of a hologram is shown. Figure 13A With 30 mol% allyl content and 30 w% thiol-ene writing monomer. Figure 13B With 43 w% thiol-ene writing monomer and 30 mol% allyl content.

[0035] Figures 14A-14B Dynamic range at 1 μm pitch ( Figure 14A ) or 0.5 μm pitch ( Figure 14B ) is shown as a function of weight % of thiol-alkyne photopolymer. Alkynes used are shown in the figure and the thiol is 1,3-bis(2-mercaptoethylthio)-2- mercaptopropane.

[0036] Figures 15A-15B Properties of thiol-alkyne photopolymers are shown. Figure 15A Dynamic range at 0.5 μm pitch is shown as a function of weight % of writing monomer using thiol-alkyne photopolymers. Thioalkynes used are shown in the figure and the thiol is 1,3-bis(2-mercaptoethylthio)-2-mercapto propane. Figure 15B Conversion during photopolymerization of 1,3-bis(2-mercaptoethylthio)-2- mercaptopropane and the indicated alkyne as a function of time is shown.

[0037] Figures 16A-16C Plots of FTIR conversion vs. time for compositions A1( Figure 16A ), B1( Figure 16B ), and C1( Figure 16C ) are shown. Mixtures consisted of 2:1 thiol / alkyne functional group concentrations at initial stoichiometric ratios. Each sample was stabilized in the dark for 1 min, then irradiated with 30 mW / cm 2 405 nm wavelength light at ambient temperature.

[0038] Figures 17A-17CThermochemical properties of thiol-yne photopolymers are shown. Plots of storage modulus and tan delta curves vs temperature for each thiol-yne photopolymer film characteristic of a step-growth network. DMA experiments were performed on samples after post-curing overnight at 70 °C.

[0039] Figure 18 is a plot of the observed refractive index as a function of thiol conversion for composition B2 after irradiation with 405 nm light (30 mW / cm 2 ).

[0040] Figures 19A-19B Properties of holograms recorded in thiol-yne photopolymers according to some embodiments are shown. Figure 19A Angular replay spectra of holograms recorded with 2d as the writing monomer are shown, showing good fit to coupled wave theory. Figure 19B is a table summarizing the dynamic range and haze of holograms measured using various alkyne writing monomers.

[0041] Figure 20 Recording of two-dimensional micron-scale refractive index structures via irradiation through a photomask on a two-stage poly(urethane-thiourethane) (Stage 1) / thiol-yne resin B2 (Stage 2) matrix is shown.

[0042] Figures 21A-21C is a real-time FTIR plot showing the formation and conversion of vinyl sulfides for compositions A (1-4) Figure 21A ), B (1-4) Figure 21B ), and C (1-4) Figure 21C ) after irradiation with 405 nm light (30 mW / cm 2 ). The mixtures were composed of an initial stoichiometric ratio of 2: 1 thiol / vinyl functionality concentration. Each sample was stabilized in the dark for 1 min before irradiation.

[0043] Figure 22 Structures of model thiol-yne monomers used to determine the reactivity of 1° and 2° thiols to mono-alkynes are shown, as well as resin compositions with a 2: 1 molar ratio of thiol and alkyne reactive groups.

[0044] Figures 23A-23B Real-time FTIR data for compositions M1 and M2 showing the reactivity of 1° and 2° thiols to mono-alkynes as a function of thiol conversion Figure 23A ) and alkyne / vinyl conversion Figure 23B ) are shown. The mixtures were composed of an initial stoichiometric ratio of 2: 1 thiol / vinyl functionality concentration. Each sample was stabilized in the dark for 1 min before irradiation. DETAILED DESCRIPTION

[0045] In one aspect, described herein is a high performance holographic recording medium based on the combination of light-initiated thiol-ene click chemistry and functional linear polymers used as binding agents, which produces a holographic material with significantly improved and stabilized average index contrast (Δn).

[0046] Reference will now be made in detail to certain embodiments of the disclosed subject matter, examples of which are illustrated in the accompanying drawings. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the example subject matter is not intended to limit the claims to the

[0047] Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of "about 0.1% to about 5%" or "about 0.1% to 5%" should be interpreted to include not only about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement "about X to Y" has the same meaning as "about X to about Y," unless otherwise indicated. Likewise, the statement "about X, Y, or about Z" has the same meaning as "about X, about Y, or about Z," unless otherwise indicated.

[0048] In this document, the terms "a," "an," or "the" are used to include one or more than one unless the context clearly dictates otherwise. The term "or" is used in the inclusive sense, unless the context clearly dictates otherwise. The statement "at least one of A and B" or "at least one of A or B" has the same meaning as "A, B, or A and B." Furthermore, it is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation. Any section headings used herein are intended for ease of understanding only and are not to be construed as limiting; information that is relevant to a section heading can occur within or outside of that particular section. All publications, patents, and patent documents cited herein are incorporated by reference in their entirety, as if each were individually incorporated by reference.

[0049] In the methods described herein, the operations can be performed in any order, unless explicitly stated otherwise or the context clearly dictates otherwise. Additionally, the specified operations can be performed concurrently, unless the claim language explicitly states otherwise. For example, an operation claimed to be performed X and an operation claimed to be performed Y can be performed concurrently within a single operation, and the resulting process would fall within the literal scope of the claimed process.

[0050] Definitions

[0051] As used herein, the term“about” can allow for a degree of variation, e.g., within 10%, within 5%, or within 1% of a value or range recited, and includes the exact value or range recited.

[0052] The term“substantially” as used herein refers to a majority or a substantial part, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. As used herein, the term“substantially free” can mean having none or a trace amount such that the amount of material present does not affect the material properties of a composition including the material, such that the composition is from about 0 wt% to about 5 wt% of the material, or from about 0 wt% to about 1 wt% of the material, or about 5 wt% or less of the material, or less than, equal to, or greater than about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt% or less, or about 0 wt% of the material. The term“substantially free” can mean having a trace amount such that the composition is from about 0 wt% to about 5 wt% of the material, or from about 0 wt% to about 1 wt% of the material, or about 5 wt% or less of the material, or less than, equal to, or greater than about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt% or less, or about 0 wt% of the material.

[0053] The term“organic group” as used herein refers to any carbon-containing functional group. Examples can include oxygen-containing groups such as alkoxy, aryloxy, aralkyloxy, oxo (carbonyl) groups; carboxylic groups including carboxylic acids, carboxylate groups, and carboxylic esters; sulfur-containing groups such as alkyl, aryl sulfide groups; and other heteroatom-containing groups. Non-limiting examples of organic groups include OR, OOR, OC(O)N(R)2, CN, CF3, OCF3, R, C(O), methylenedioxy, ethylenedioxy, N(R)2, SR, SOR, SO2R, SO2N(R)2, SO3R, C(O)R, C(O)C(O)R, C(O)CH2C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R)2, OC(O)N(R)2, C(S)N(R)2, (CH2) 0-2 N(R)C(O)R, (CH2) 0-2N(R)N(R)2, N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R)2, N(R)SO2R, N(R)SO2N(R)2, N(R)C(O)OR, N(R)C(O)R, N(R)C(S)R, N(R)C(O)N(R)2, N(R)C(S)N(R)2, N(COR)COR, N(OR)R, C(=NH)N(R)2, C(O)N(OR)R, C(=NOR)R, and substituted or unsubstituted (C1-C 100 )hydrocarbyl, where R can be hydrogen (in instances including other carbon atoms) or a carbon-based moiety, and where the carbon-based moiety can be substituted or unsubstituted.

[0054] The term "substituted" used in connection with a molecule or organic group defined herein refers to a state in which one or more of the hydrogen atoms contained therein are replaced by one or more non-hydrogen atoms. The term "functional group" or "substituent" as used herein refers to a group that can be substituted or substituted onto a molecule or organic group. Examples of substituents or functional groups include, but are not limited to, halogens (e.g., F, Cl, Br, and I); oxygen atoms in groups such as hydroxyl, alkoxy, aryloxy, aralkyloxy, oxo (carbonyl) groups, carboxyl (including carboxylic acids, carboxylate groups, and carboxylic esters); sulfur atoms in groups such as thiol, alkyl and aryl sulfide groups, sulfoxide groups, sulfone groups, sulfonyl groups, and sulfonamide groups; nitrogen atoms in groups such as amines, hydroxylamines, nitriles, nitro groups, N-oxides, hydrazides, azides, and enamines; and other heteroatoms in various other groups. Non-limiting examples of substituents that can be bonded to a substituted carbon (or other) atom include F, Cl, Br, I, OR, OC(O)N(R)2, CN, NO, NO2, ONO2, azido, CF3, OCF3, R, O(oxo), S(thiono), C(O), S(O), methylenedioxy, ethylenedioxy, N(R)2, SR, SOR, SO2R, SO2N(R)2, SO3R, C(O)R, C(O)C(O)R, C(O)CH2C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R)2, OC(O)N(R)2, C(S)N(R)2, (CH2) 0-2 N(R)C(O)R, (CH2) 0-2N(R)N(R)2, N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R)2, N(R)SO2R, N(R)SO2N(R)2, N(R)C(O)OR, N(R)C(O)R, N(R)C(S)R, N(R)C(O)N(R)2, N(R)C(S)N(R)2, N(COR)COR, N(OR)R, C(=NH)N(R)2, C(O)N(OR)R, and C(=NOR)R, wherein R can be hydrogen or a carbon-based moiety; for example, R can be hydrogen, (Ci-C 100 )hydrocarbyl, alkyl, acyl, cycloalkyl, aryl, aralkyl, heterocyclyl, heteroaryl, or heteroarylalkyl; or wherein two R groups bonded to a nitrogen atom or adjacent nitrogen atoms can together form a heterocyclyl group.

[0055] As used herein, the term "alkyl" refers to straight and branched chain alkyl and cycloalkyl groups having from 1 to 40 carbon atoms, from 1 to about 20 carbon atoms, from 1 to 12 carbon atoms, or in some embodiments, from 1 to 8 carbon atoms. Examples of straight chain alkyl groups include those having from 1 to 8 carbon atoms such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl. Examples of branched alkyl groups include, but are not limited to, isopropyl, isobutyl, sec-butyl, t-butyl, neopentyl, isopentyl, and 2,2-dimethylpropyl. As used herein, the term "alkyl" encompasses n-alkyl, i-alkyl, and syn-i-alkyl groups as well as other branched forms of alkyl groups. Representative substituted alkyl groups can be substituted one or more times with any of the groups listed herein, for example, amino, hydroxyl, cyano, carboxyl, nitro, thio, alkoxy, and halogen groups.

[0056] As used herein, the term "alkenyl" refers to straight and branched chain and cyclic alkyl groups as defined herein except that at least one double bond exists between two carbon atoms. Thus, alkenyl groups have from 2 to 40 carbon atoms, or from 2 to about 20 carbon atoms, or from 2 to 12 carbon atoms, or in some embodiments, from 2 to 8 carbon atoms. Examples include, but are not limited to, ethenyl, -CH=C=CCH2, -CH=CH(CH3), -CH=C(CH3)2, -C(CH3)=CH2, -C(CH3)=CH(CH3), -C(CH2CH3)=CH2, cyclohexenyl, cyclopentenyl, cyclohexadienyl, butadienyl, pentadienyl, and hexadienyl, and the like.

[0057] The term "alkynyl" as used herein refers to straight chain and branched chain alkyl groups except that at least one triple bond exists between two carbon atoms. Thus, alkynyl groups have 2 to 40 carbon atoms, 2 to about 20 carbon atoms, or 2 to 12 carbons, or in some embodiments 2 to 8 carbon atoms. Examples include, but are not limited to, -C≡CH, -C≡C(CH3), -C≡C(CH2CH3), -CH2C≡CH, -CH2C≡C(CH3), and -CH2C≡C(CH2CH3), and the like.

[0058] The term "acyl" as used herein refers to a group containing a carbonyl moiety, wherein the group is bonded through the carbonyl carbon atom. The carbonyl carbon atom is bonded to hydrogen to form a "formyl" group or to another carbon atom, which can be part of an alkyl, aryl, aralkyl cycloalkyl, cycloalkylalkyl, heterocyclyl, heterocyclylalkyl, heteroaryl, heteroarylalkyl, or the like group. Acyl groups can include from 0 to about 12, 0 to about 20, or 0 to about 40 additional carbon atoms bonded to the carbonyl. Acyl groups can include double or triple bonds within the meaning herein. Propenoyl is an example of an acyl group. Acyl groups can also include heteroatoms within the meaning herein. Nicotinoyl (pyridyl-3-carbonyl) is an example of an acyl group within the meaning herein. Other examples include acetyl, benzoyl, phenylacetyl, pyridylacetyl, cinnamoyl, and propenoyl, and the like. When a group containing a carbon atom bonded to the carbonyl carbon atom contains a halogen, the group is referred to as a "haloacyl." An example is trifluoroacetyl.

[0059] The term "cycloalkyl" as used herein refers to cyclic alkyl groups such as, but not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. In some embodiments, cycloalkyl groups can have from 3 to about 8-12 ring members, while in other embodiments, the number of ring carbon atoms ranges from 3 to 4, 5, 6, or 7. Cycloalkyl further includes polycyclic cycloalkyl groups such as, but not limited to, norbornyl, adamantyl, bornyl, camphenyl, isocamphenyl, and carenyl; as well as fused rings such as, but not limited to, decalinyl, and the like. Cycloalkyl also includes rings that are substituted with straight chain or branched chain alkyl groups as defined herein. Representative substituted cycloalkyl groups can be mono- or polysubstituted, such as, but not limited to, 2,2-, 2,3-, 2,4-, 2,5-, or 2,6-disubstituted cyclohexyl or mono-, di- or tri-substituted norbornyl or cycloheptyl groups, which can be substituted, for example, with amino, hydroxyl, cyano, carboxyl, nitro, sulfur, alkoxy, and halogen groups. The term "cycloalkenyl" alone or in combination denotes cyclic alkenyl groups.

[0060] As used herein, the term "aryl" refers to a cyclic aromatic hydrocarbon group that does not contain heteroatoms in the ring. Therefore, aryl groups include, but are not limited to, phenyl, azulel, heptalenyl, biphenyl, indacenyl, fluorenyl, phenanthrene, triphenylenyl, pyrene, and naphthacenyl. The aryl group comprises chrysenyl, biphenylene, anthracene, and naphthyl. In some embodiments, the aryl group contains about 6 to about 14 carbons in the ring moiety of the group. As defined herein, the aryl group can be unsubstituted or substituted. Representative substituted aryl groups can be monosubstituted or substituted more than once, such as, but not limited to, phenyl groups substituted at any one or more of the 2, 3, 4, 5, or 6 positions of the benzene ring, or naphthyl groups substituted at any one or more of the 2 to 8 positions.

[0061] As used herein, the term "aralkyl" refers to an alkyl group as defined herein—where the hydrogen or carbon bond of the alkyl group is substituted to a bond of an aryl group as defined herein. Representative aralkyl groups include benzyl and phenethyl, as well as fused (cycloalkylaryl)alkyl groups such as 4-ethyl-indenyl. Arylene is an alkenyl group as defined herein—where the hydrogen or carbon bond of the alkyl group is substituted to a bond of an aryl group as defined herein.

[0062] As used herein, the term "heterocyclic group" refers to an aromatic and non-aromatic cyclic compound containing three or more ring members, one or more of which are heteroatoms, such as, but not limited to, N, O, and S. Thus, a heterocyclic group can be a cycloheteroalkyl or heteroaryl group, or, if polycyclic, any combination thereof. In some embodiments, a heterocyclic group comprises 3 to about 20 ring members, while other such groups have 3 to about 15 ring members. A heterocyclic group named C2-heterocyclic group can be a 5-ring having two carbon atoms and three heteroatoms, a 6-ring having two carbon atoms and four heteroatoms, etc. Similarly, a C4-heterocyclic group can be a 5-ring having one heteroatom, a 6-ring having two heteroatoms, etc. The number of carbon atoms plus the number of heteroatoms equals the total number of ring atoms. The heterocyclic ring may also include one or more double bonds. A heteroaryl ring is one embodiment of a heterocyclic group. The phrase "heterocyclic group" includes fused rings, which include those comprising fused aromatic and non-aromatic groups. For example, dioxolane and benzodioxolane systems (methylene dioxophenyl ring systems) are both heterocyclic groups as understood herein. This phrase also includes polycyclic systems containing heteroatoms, such as, but not limited to, quinine groups. Heterocyclic groups may be unsubstituted or may be substituted as described herein. Heterocyclic groups include, but are not limited to, pyrrolidinyl, piperidinyl, piperazine, morpholinyl, pyrrolidinyl, pyrazolyl, triazolyl, tetrazolyl, and others. azole group, iso oxazolyl, thiazolyl, pyridyl, thienyl, benzothienyl, benzofuranyl, dihydrobenzofuranyl, indolyl, dihydroindolyl, azaindolyl, indazolyl, benzimidazolyl, azabenzimidazolyl, benzo oxazolyl, benzothiazolyl, benzothiadiazolyl, imidazopyridinyl, iso oxazolyl, benzothiazolyl, benzothiadiazolyl, imidazopyridinyl, iso

[0063] The term "heteroaryl" as used herein refers to aromatic ring compounds containing 5 or more ring members, one or more of the ring members being a heteroatom, such as, but not limited to, N, O, and S; for example, a heteroaryl ring can have from 5 to about 8-12 ring members. Heteroaryl is a class of heterocyclyl groups that have aromatic electronic structure. A heteroaryl named as C2-heteroaryl can be a 5-ring with two carbon atoms and three heteroatoms, a 6-ring with two carbon atoms and four heteroatoms, etc. Likewise, a C4-heteroaryl can be a 5-ring with one heteroatom, a 6-ring with two heteroatoms, etc. The number of carbon atoms plus the number of heteroatoms sums to the total number of ring atoms. Heteroaryl includes, but is not limited to, groups such as pyrrolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, benzothiazolyl, benzothiadiazolyl, imidazopyridinyl, iso oxazolyl, thiazolyl, pyridyl, thienyl, benzothienyl, benzofuranyl, indolyl, azaindolyl, indazolyl, benzimidazolyl, azabenzimidazolyl, benzo oxazolyl, benzothiazolyl, benzothiadiazyl, imidazopyridinyl, iso oxazolyl, benzothiazolyl, benzothiadiazyl, imidazopyridinyl, iso

[0064] Other examples of aryl and heteroaryl include, but are not limited to, phenyl, biphenyl, indenyl, naphthyl (1-naphthyl, 2-naphthyl), N-hydroxytetrazolyl, N- hydroxytriazolyl, N-hydroxyimidazolyl, anthryl (1-anthryl, 2-anthryl, 3-anthryl), thienyl (2-thienyl, 3-thienyl), furanyl (2-furanyl, 3-furanyl), indolyl, oxazolyl, benzothiazolyl, benzothiadiazyl, imidazopyridinyl, iso Azolyl, quinazolinyl, fluorenyl, xanthyl, isoindanyl, diphenylmethyl, acridineyl, thiazolyl, pyrrolyl (2-pyrrolyl), pyrazolyl (3-pyrazolyl), imidazoleyl (1-imidazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl), triazolyl (1,2,3-triazol-1-yl, 1,2,3-triazol-2-yl, 1,2,3-triazol-4-yl, 1,2,4-triazol-3-yl) azole (2- azole group, 4- azole, 5- (Azolyl), thiazolyl (2-thiazolyl, 4-thiazolyl, 5-thiazolyl), pyridyl (2-pyridyl, 3-pyridyl, 4-pyridyl), pyrimidinyl (2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl, 6-pyrimidinyl), pyrazinyl, pyridazinyl (3-pyridazinyl, 4-pyridazinyl, 5-pyridazinyl), quinolinyl (2-quinolinyl, 3-quinolinyl, 4-quinolinyl, 5-quinolinyl, 6-quinolinyl, 7-quinolinyl, 8-quinolinyl), isoquinolinyl (1-isoquinolinyl, 3-isoquinolinyl, 4-isoquinolinyl, 5-isoquinolinyl, 6-isoquinolinyl, 7-isoquinolinyl) Quinolinyl, 8-isoquinolinyl), benzo[b]furanyl (2-benzo[b]furanyl, 3-benzo[b]furanyl, 4-benzo[b]furanyl, 5-benzo[b]furanyl, 6-benzo[b]furanyl, 7-benzo[b]furanyl), 2,3-dihydro-benzo[b]furanyl (2-(2,3-dihydro-benzo[b]furanyl), 3-(2,3-dihydro-benzo[b]furanyl), 4-(2,3-dihydro-benzo[b]furanyl), 5-(2,3-dihydro-benzo[b]furanyl), 6-(2,3-dihydro-benzo[b]furanyl) [b]furanyl), 7-(2,3-dihydro-benzo[b]furanyl), benzo[b]thiophene (2-benzo[b]thiophene, 3-benzo[b]thiophene, 4-benzo[b]thiophene, 5-benzo[b]thiophene, 6-benzo[b]thiophene, 7-benzo[b]thiophene), 2,3-dihydro-benzo[b]thiophene (2-(2,3-dihydro-benzo[b]thiophene), 3-(2,3-dihydro-benzo[b]thiophene), 4-(2,3-dihydro-benzo[b]thiophene), 5-(2,3-dihydro-benzo[b]thiophene) phenylyl), 6-(2,3-dihydro-benzo[b]thiophenyl), 7-(2,3-dihydro-benzo[b]thiophenyl), indoleyl (1-indoleyl, 2-indoleyl, 3-indoleyl, 4-indoleyl, 5-indoleyl, 6-indoleyl, 7-indazoleyl), indazoleyl (1-indazoleyl, 3-indazoleyl, 4-indazoleyl, 5-indazoleyl, 6-indazoleyl, 7-indazoleyl), benzimidazoleyl (1-benzimidazoleyl, 2-benzimidazoleyl, 4-benzimidazoleyl, 5-benzimidazoleyl, 6-benzimidazoleyl, 7-benzimidazoleyl, 8-benzimidazoleyl), benzo[b] oxazolyl (1-oxazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 6-oxazolyl, 7-oxazolyl), pyridyl (2-pyridyl, 3-pyridyl, 4-pyridyl), pyrimidinyl (2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl, 6-pyrimidinyl), pyrazinyl (2-pyrazinyl), pyridazinyl (3-pyridazinyl, 4-pyridazinyl), thiazolyl (2-thiazolyl, 4-thiazolyl, 5-thiazolyl), isothiazolyl (3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl), isoxazolyl (3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl), furazanyl (2-furazanyl, 3-furazanyl), furanyl (2-furanyl, 3-furanyl), thiophenyl (2-thiophenyl, 3-thiophenyl), imidazolyl (1-imidazolyl, 2-imidazolyl, 4-imidazolyl, 5-imidazolyl), pyrrolyl (1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl), pyrazolyl (1-pyrazolyl, 3-pyrazolyl, 5-pyrazolyl), triazolyl (1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,5-triazolyl, 1,3,4-triazolyl, 1,3,5-triazolyl), tetrazolyl (1-tetrazolyl, 2-tetrazolyl, 5-tetrazolyl), oxadiazolyl (1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, 1,3,5-oxadiazolyl), thiadiazolyl (1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,3,4-thiadiazolyl, 1,3,5-thiadiazolyl), carbazolyl (1-carbazolyl, 2-carbazolyl, 3-carbazolyl, 4-carbazolyl), 5H-dibenzo[b,f]azepinyl (1-5H-dibenzo[b,f]azepinyl, 2-5H-dibenzo[b,f]azepinyl, 3-5H-dibenzo[b,f]azepinyl, 4-5H-dibenzo[b,f]azepinyl, 5-5H-dibenzo[b,f]azepinyl), 10,11-dihydro-5H-dibenzo[b,f]azepinyl (1-10,11-dihydro-5H-dibenzo[b,f]azepinyl, 2-10,11-dihydro-5H-dibenzo[b,f]azepinyl, 3-10,11-dihydro-5H-dibenzo[b,f]azepinyl, 4-10,11-dihydro-5H-dibenzo[b,f]azepinyl, 5-10,11-dihydro-5H-dibenzo[b,f]azepinyl), benzoxazolyl (1-benzoxazolyl, 2-benzoxazolyl, 5-benzoxazolyl, 6-benzoxazolyl, 7-benzoxazolyl), benzothiazolyl (1-benzothiazolyl, 2-benzothiazolyl, 4-benzothiazolyl, 5-benzothiazolyl, 6-benzothiazolyl, 7-benzothiazolyl), benzimidazolyl (1-benzimidazolyl, 2-benzimidazolyl, 4-benzimidazolyl, 5-benzimidazolyl, 6-benzimidazolyl, 7-benzimidazolyl), indolyl (1-indolyl, 2-indolyl, 3-indolyl, 4-indolyl, 5-indolyl, 6-indolyl), indazolyl (1-indazolyl, 2-indazolyl, 4-indazolyl, 5-indazolyl, 6-indazolyl, 7-indazolyl), quinazolinyl (1-quinazolinyl, 2-quinazolinyl, 4-quinazolinyl, 5-quinazolinyl, 6-quinazolinyl, 7-quinazolinyl), quinolyl (1-quinolyl, 2-quinolyl, 3-quinolyl, 4-quinolyl, 5-quinolyl, 6-quinolyl, 7-quinolyl), isoquinolyl (1-isoquinolyl, 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl, 6-isoquinolyl, 7-isoquinolyl), purinyl (1-purinyl, 2-purinyl, 6-purinyl, 8-purinyl), benzofuranyl (1-benzofuranyl, 2-benzofuranyl, 3-benzofuranyl, 4-benzofuranyl, 5-benzofuranyl, 6-benzofuranyl), benzothiophenyl (1-benzothiophenyl, 2-benzothiophenyl, 3-benzothiophenyl, 4-benzothiophenyl, 5-benzothiophenyl, 6-benzothiophenyl), benzodioxolyl (1-benzodioxolyl, 2-benzodioxolyl, 3-benzodioxolyl, 4-benzodioxolyl, 5-benzodioxolyl, 6-benzodioxolyl), benzodioxolyl (1-benzodioxolyl, 2-benzodioxolyl, 3-benzodioxolyl, 4-benzodioxolyl, 5-benzodioxolyl, 6-benzodioxolyl), and the like.

[0065]

[0066]

[0067] ​​​​​​​​​​​​​​​​The term "alkoxy" as used herein refers to an oxygen atom linked to an alkyl group (including cycloalkyl) as defined herein. Examples of straight-chain alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, and the like. Examples of branched alkoxy groups include, but are not limited to, isopropoxy, sec-butoxy, tert-butoxy, isopentoxy, isohexoxy, and the like. Examples of cyclic alkoxy groups include, but are not limited to, cyclopropoxy, cyclobutoxy, cyclopentoxy, cyclohexoxy, and the like. Alkoxy groups can include from about 1 to about 12, from about 1 to about 20, or from about 1 to about 40 carbon atoms bonded to the oxygen atom, and can further include double or triple bonds, and can also include heteroatoms. For example, allyloxy or methoxyethoxy are also alkoxys within the meaning herein, as is methylenedioxy in the case of two adjacent atoms of the structure being substituted thereby.

[0068] The term "amine" as used herein refers to primary, secondary, and tertiary amines of the formula N(group)3, where each group can be independently H or non-H, such as alkyl, aryl, and the like. Amines include, but are not limited to, R-NH2, such as alkylamines, arylamines, alkylaryl amines; R2NH, where each R is independently selected, such as dialkylamines, diaryl amines, aralkylamines, heterocyclyl amines, and the like; and R3N, where each R is independently selected, such as trialkylamines, dialkylaryl amines, alkyl diaryl amines, triaryl amines, and the like. The term "amine" also includes ammonium ions as used herein.

[0069] The term "amino" as used herein refers to -NH2, -NHR, -NR2, -NR3 + the formula, where each R is independently selected, and the protonated form of each, except -NR3 + which cannot be protonated. Thus, any amino-substituted compound can be considered an amine. "Amino" within the meaning herein can be a primary amino group, a secondary amino group, a tertiary amino group, or a quaternary amino group. "Alkylamino" includes monoalkylamino, dialkylamino, and trialkylamino groups.

[0070] The term "halo," "halogen," or "halo" group as used herein by itself or as part of another substituent means a fluorine, chlorine, bromine, or iodine atom, unless otherwise stated.

[0071] The term "haloalkyl" group as used herein includes mono-haloalkyl, poly-haloalkyl, where all halogen atoms can be the same or different, and per-haloalkyl, where all hydrogen atoms are replaced by halogen atoms, such as fluorine. Examples of haloalkyl groups include trifluoromethyl, 1,1-dichloroethyl, 1,2-dichloroethyl, 1,3-dibromo-3,3-difluoropropyl, perfluorobutyl, and the like.

[0072] The term "epoxy functional" or "epoxy substituted" as used herein refers to a functional group in which an oxygen atom, the epoxy substituent, is directly attached to two adjacent carbon atoms of a carbon chain or ring system. Examples of epoxy substituted functional groups include, but are not limited to, 2,3-epoxypropyl, 3,4-epoxybutyl, 4,5-epoxypentyl, 2,3-epoxypropoxy, epoxypropoxypropyl, 2-glycidyloxyethyl, 3-glycidyloxypropyl, 4-glycidyloxybutyl, 2-(glycidyloxycarbonyl)propyl, 3-(3,4-epoxycyclohexyl)propyl, 2-(3,4-epoxycyclohexyl)ethyl, 2-(2,3-epoxycyclopentyl)ethyl, 2-(2,3-epoxy-3-methylcyclohexyl)propyl, 2-(3,4-epoxy-3-methylcyclohexyl)-2-methylethyl, and 5,6-epoxyhexyl.

[0073] The term "monovalent" as used herein refers to a substituent that is attached to a substituted molecule via a single bond. When the substituent is monovalent, as for example F or CI, it is bonded to the atom it is substituting by a single bond.

[0074] The term "hydrocarbon" or "hydrocarbyl" as used herein refers to a molecule or functional group that includes carbon and hydrogen atoms. The term can also refer to a molecule or functional group that typically includes carbon atoms and hydrogen atoms, but in which all of the hydrogen atoms are substituted with other functional groups.

[0075] As used herein, the term "hydrocarbyl" refers to a functional group derived from a linear, branched, or cyclic hydrocarbon, and can be an alkyl, alkenyl, alkynyl, aryl, cycloalkyl, acyl, or any combination thereof. A hydrocarbyl group can be represented as (C a -C b )hydrocarbyl, where a and b are integers and mean having any number of carbon atoms in the range of a to b. For example, (C1-C4)hydrocarbyl means that the hydrocarbyl group can be methyl (C1), ethyl (C2), propyl (C3), or butyl (C4), and (C0-C b )hydrocarbyl means that there is no hydrocarbyl group in certain embodiments.

[0076] As used herein, the term "solvent" refers to a liquid that can dissolve a solid, liquid, or gas. Non-limiting examples of solvents are silicones, organic compounds, water, alcohols, ionic liquids, and supercritical fluids.

[0077] The term "independently selected from" as used herein means that the group is the same, different, or a mixture thereof, unless the context clearly dictates otherwise. Thus, under this definition, the phrase "X 1 , X 2 , and X 3 are independently selected from inert gases" would include the case where, for example, X 1 , X 2 , and X 3 are all the same, where X1 , X 2 and X 3 are all different, where X 1 and X 2 are the same but X 3 is different, and other similar permutations.

[0078] The term "room temperature" as used herein refers to a temperature of about 15 °C to 28 °C.

[0079] The term "standard temperature and pressure" as used herein refers to 20 °C and 101 kPa.

[0080] Monomers for holographic recording

[0081] Compounds of Formula (I) or otherwise described herein can be prepared by the general schemes described herein, utilizing synthetic methods known to those skilled in the art. The following examples illustrate non-limiting embodiments of the compounds (one or more) described herein and their preparation.

[0082] In certain embodiments, a composition suitable for holographic recording includes:

[0083] at least one polymer;

[0084] a polymeric binding agent comprising a plurality of allyl groups; and

[0085] at least one monomer of Formula (I):

[0086]

[0087] and at least one monomer of Formula (II):

[0088]

[0089] wherein:

[0090] each occurrence of X is independently H, optionally substituted C 1-12 hydrocarbyl, or optionally substituted C 6-14 aryl;

[0091] each Y is independently -S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, -CH(SH)-, -CH[O-CH2-CH=CH2]-, or -CH[O-CH2-C≡CH]-;

[0092] each occurrence of Y T is independently H, -SH, -CH2SH, -CH=CH2, -C≡CH, or optionally substituted C 6-14 aryl;

[0093] each Z is independently -S-, -CH2, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, or -CH(SH)-;

[0094] each Z T is independently H, -SH, or -CH2SH;

[0095] m is an integer ranging from 0 to 100; and

[0096] n is an integer ranging from 0 to 100.

[0097] In the monomer of Formula (I), (Y) m -Y T means a series of "m" Y moieties bonded to one another with a terminal Y T moiety. Thus, for example, (Y)2-Y T means Y-Y-Y T where each Y and Y T are independently selected as described herein. Similarly, in the monomer of Formula (II), (Z)2-Z T means Z-Z-Z T where each Z T are independently selected as described herein. In the monomers of Formula (I) and Formula (II), the terminal Y T or Z T group is selected such that a chemically stable compound is formed. In various embodiments, the terminal Y T group can be an optionally substituted C 6-14 aryl group. In various embodiments, the terminal Z T group is -SH or -CH2SH.

[0098] In one embodiment, the polymer is a linear polyurethane. Other suitable polymers can include polymers that are useful as the holographic recording medium described herein and are known in the art. In some embodiments, the polymer can be a block copolymer. Suitable block copolymers can include polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone (M n ~2000), as described herein.

[0099] In an embodiment, the polymeric binder comprises about 0 to about 80 mol% allyl groups. In an embodiment, the polymeric binder contains about 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or about 100 mol% allyl groups. In an embodiment, the polymer comprises polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone. In various embodiments, the mol% of allyl groups is relative to the total moles of monomer / binder and block copolymer comprising allyl groups.

[0100] In various embodiments, the ratio of the monomer of Formula (I) to the monomer of Formula (II) is about 9: 1 to about 1:9. The ratio of Formula (I) : Formula (II) can take any value between 9: 1 to 1:9, and in various embodiments, the ratio of Formula (I) : Formula (II) can be about 9: 1, 8.5: 1.5, 8:2, 7.5:2.5, 7:3, 6.5:3.5, 6:4, 5.5:4.5, 1:1, 4.5:5.5, 4:6, 3.5:6, 3:7, 2.5:7.5, 2:8, 1.5:8.5, or about 1:9. In various embodiments, the ratio of the monomer of Formula (I) to the monomer of Formula (II) is the stoichiometric ratio between the thiol group in Formula (II) and the alkenyl or alkynyl group in Formula (I).

[0101] In various embodiments, (Z) includes at least one -SH moiety. n In various embodiments, (Z) includes at least one -SH moiety. n In various embodiments, (Z) includes at least two -SH moieties. n In various embodiments, (Z) includes at least three -SH moieties. In various embodiments, the monomer of Formula (II) is selected from:

[0102]

[0103] In various embodiments, X can be C 6-10 aryl. In some embodiments, X is phenyl. In various embodiments, (Y) includes at least one -SH moiety. mis a straight chain. In one embodiment, (Y) m may be at least one -CH(O-CH2-CH=CH2)- or -CH(O-CH2-C≡CH)- moiety. In another embodiment, (Y) m may be at least two moieties independently selected from -CH(O-CH2-CH=CH2)- and -CH(O-CH2-C≡CH)-.

[0104] In certain embodiments, the monomer of formula (I) is selected from:

[0105]

[0106]

[0107] In one embodiment, the monomer of formula (I) and the monomer of formula (II) together can be about 1 to 80% (w / w) of the composition. In some embodiments, the monomers can be about 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, or about 80% (w / w) of the composition.

[0108] In one embodiment, the composition described herein is polymerized. In some embodiments, the polymerized composition can be polymerized using light such as a laser, a photoinitiator, a free radical initiator, a transition metal complex, and the like.

[0109] In various embodiments, the hologram produced by the method of the claims has a refractive index modulation (An) of about 0.01 to about 0.06. In one embodiment, the hologram described herein has a refractive index modulation (An) of about 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, or about 0.06. In some embodiments, the monomers of formula (I) and formula (II) form a solution with the polymeric binder.

[0110] In one embodiment, in the polymerized composition, the plurality of allyl groups and monomers are crosslinked. The crosslinking can be between, for example, the allyl groups of the polymer binder and one or more thiol groups, allyl groups, or propargyl groups in the monomers. In some embodiments, the un-polymerized compositions described herein can be cast into films.

[0111] The refractive index of the network polymer can be further extended compared to conventional high refractive index polymer systems via the formation of thioether linkages. To achieve this goal, a series of high refractive index writing monomers containing thiol, alkene, and alkyne functional groups were designed and synthesized as described herein. Each monomer contains a flexible high refractive index core comprising aryl and / or thioether groups. Utilizing the advantages of step-growth thiol-alkene and thiol-alkyne "click" reactions such as negligible oxygen sensitivity and reduced shrinkage, superior control over material properties such as refractive index, dispersion, viscosity, glass transition temperature, etc. can be achieved.

[0112] In some embodiments, the monomers described herein exhibit a high refractive index in the range of 1.59-1.67. Photopolymerization of pure thiol-alkene and thiol-alkyne resins using TPO photoinitiators yields n D values in the range of 1.6-1.7. A set of exemplary RI values for the synthesized monomers and photopolymers measured at a wavelength of 589 nm are shown in Table 1 below.

[0113] Table 1: Table of refractive indices measured at 25°C and a wavelength of 589 nm for the synthesized liquid writing monomers and their photopolymer mixtures after curing.

[0114]

[0115] Here, as Figures 1A-1D described in the examples, high dynamic range (Δn) holographic media based on thiol-alkene click chemistry were designed and implemented. 1,3-bis(2-mercaptoethylthio)-2- mercaptopropane (BMEMP, trithiol, Figure 1A ) and 1,2-ethanedithiol-based diallyl ether (EDTDAE, diene, Figure 1A ) were chosen as writing monomers - based on their ability to form high refractive index polymers from readily available precursors (Table 2) through a simple synthetic route.

[0116] Table 2. Refractive indices of writing monomers.

[0117]

[0118] a) Abbe number = (n d -1) / (n f -n c )

[0119] Linear polyurethane binders were synthesized via step-growth polymerization of diols (trimethylolpropane allyl ether (TMPAE) and a polyol Mw ~ 2000) and diisocyanates (hexamethylene diisocyanate), which can be subsequently dissolved in a volatile organic solvent along with the writing monomer and photoinitiator, in a similar fashion to how holographic crosslinked binders are produced in the conventional two-step approach. Due to the orthogonal matrix formation and writing chemistry required in the conventional two-step strategy, it is difficult to utilize the thiol-X reaction as the writing chemistry in combination with a conventionally polymerized crosslinked polyurethane matrix, as there can be cross-reactions between the thiols from the writing monomer and the isocyanates from the binder.

[0120] It was surprisingly discovered that having the binder as a linear polymer can decouple these two processes, allowing for the formation of a low refractive index, urethane-based binder in the absence of a thiol writing monomer. These polymers were formed with varying levels of TMPAE to facilitate varying levels of thiol-ene writing monomer attachment and matrix crosslinking. After blade coating and thermal annealing, films of controlled thickness in the range of 3-30 microns were prepared and used for holographic recording. Transmission holograms were recorded by exposing the sample to two interfering 405 nm laser beams ( Figure 11 ). The hologram diffraction efficiency was monitored in real-time using a 633 nm probe beam (to which the medium is not sensitive). A relatively low intensity exposure of less than 10 seconds was required to achieve the highest diffraction efficiency (DE) ( Figure 4 ), during which time the thiol and ene monomers reacted with each other and with the pendant ene functionality on the linear polymer to form a crosslinked matrix only within the exposed area of the film. After exposure, angular playback was performed using the same 633 nm probe beam to monitor the diffraction efficiency as a function of angular detuning.

[0121] Figure 2B The highest achievable holographic index modulation achieved under different loading of writing monomer (for transmission holograms with a fringe spacing Λ = 0.5 μm) is shown. As expected, higher writing monomer loading generally resulted in higher index modulation, in some cases up to 0.04. One exception was the control composition where the binder did not contain allyl side groups. Here, as the writing monomer loading was increased up to 40 wt%, the index modulation sharply decreased. It is envisioned that at this high loading, the writing monomer phase separated from the binder after polymerization, reducing the optical transparency and correspondingly the diffraction efficiency. However, when allyl reactive sites were present on the linear polymer binder, the binder and writing polymer reacted together to form a single crosslinked network in the exposed area, preventing phase separation and that enabled the use of high monomer loadings. To illustrate the effect of the allyl side chains, the same data was re-plotted with the allyl loading as the independent variable ( Figures 7A-7BOverall, an optimal allyl content exists: low allyl content indicates insufficient anchoring, while excessive allyl can interfere with thiol-olefin photopolymerization.

[0122] Next, the diffusion-alblurring effect was evaluated in the presence of allyl reaction sites on the binder. To this end, the holographic performance at two different spatial frequencies (corresponding to spacing Λ = 0.5 μm vs 1 μm) was compared. Figures 7A-7B (As shown). In the absence of an allyl reaction site, exponential modulation decreases significantly at higher spatial frequencies due to diffusion ambiguity. When an allyl reaction site is present, exponential modulation remains almost unchanged as a function of spatial frequency, as shown. Figure 2C As shown, through the reaction, the writing polymer is effectively anchored to and immobilized at the binder reaction site, resulting in a significant reduction in diffusion fuzziness. Figures 9A-9B The performance of all components except the control group was demonstrated, and the significant tunability of the thiol olefin holograms in terms of dynamic range was shown.

[0123] exist Figure 2D In this field, atomic force microscopy (AFM) with small surface undulations enables direct visualization of recorded fringes. The measured fringe spacing is consistent with the nominal value, and all constituent fringes exhibit excellent homogeneity. Figures 13A-13B ). Figures 13A-13B The surface undulations within the film are on the order of 10 nm, and their contribution to optical diffraction is negligible compared to the volume exponential changes within the film. This observation was confirmed by applying an exponentially matched fluid and a coverslip during holographic playback and achieving the same result.

[0124] Finally, to further demonstrate the performance of this thiol-olefin recording medium at higher spatial frequencies, reflection holograms were recorded. Overall, exponential modulation typically decreases sharply at these smaller pitches due to diffusion blurring. However, improved performance of the reflection holograms is expected in this system due to the introduction of covalent chemical bonds between the polymer binder and the writing monomer. Recording was performed using a single-beam Denisyuk configuration at a pitch Λ = 140 nm, with a nominal reflection notch (notch) of approximately 405 nm. In one embodiment, the composition derived from previous transmission experiments (30 mol% allyl and 43 wt% thiol-olefin writing monomer) was used. A thicker film of ~25 μm was obtained via repeated scraping, producing an acceptable surface profile. Figure 6 ). Figure 4 The typical holographic transmission spectrum is shown (after 10 seconds of exposure). For comparison, the predictions of the Kogelnik coupled-wave model are also shown (note that the exponential modulation and film thickness were manually selected, rather than being least-squares fitted parameters as before). This performance indicates that the exponential modulation exceeds 5 x 10^6.-3 , indicating a significant drop relative to the larger pitch transmission case (4x 10 -2 ) but still sufficient to achieve diffraction efficiencies better than 90% in these relatively thin films. The central spectral broadening notch is a signature of Kogelnik overmodulation, indicating good grating uniformity throughout the sample thickness.

[0125] In summary, a combination of thiol-ene click chemistry and linear functionalized polymeric binders was implemented to produce holographic materials capable of achieving high dynamic ranges. Due to the selection of a linear low-RI polyurethane matrix, a roll-to-roll doctor blade coating process was employed to produce the holographic films. By incorporating optimal reactive allyl side chains into the linear polyurethane polymeric binder, a high dynamic range of over 0.04 was achieved, which addresses the problem of diffraction blur at high spatial frequencies. Significant overmodulated reflection holograms were displayed to demonstrate the superior performance and reduced diffraction blur of the films at very high spatial frequencies.

[0126] Method of recording a hologram

[0127] In one embodiment, a method of recording a hologram is provided. The method includes providing a composition containing a polymeric binder, a monomer of Formula (I), and a monomer of Formula (II) as described herein, and exposing the composition to laser irradiation to form a hologram. The laser irradiation can include the use of two laser beams from suitable sources such as Figure 11 . The hologram can also be recorded using other art-recognized methods. The hologram generated by the claimed method can be used in applications such as cue displays in vehicles and aircraft, holographic data storage, and holographic optical elements.

[0128] In some embodiments, the providing step can include covering an inert substrate with the film. Suitable inert substrates can include glass, plastic, metal, semiconductor materials, ceramic, rubber, and combinations of these materials. In one embodiment, the exposing step can include crosslinking the polymeric binder with the monomers of Formula (I) and Formula (II).

[0129] High refractive index photopolymer

[0130] In various embodiments, the compounds of Formula (I-A) and Formula (II) can be crosslinked to form a high refractive index photopolymer. High refractive index polymers (HRIPs) are considered an attractive alternative to silicon and glass for use in various optoelectronic applications due to their light weight, ease of processing, low cost, and overall versatility of material properties control. While significant progress has been made in developing intrinsic HRIPs, most of these strategies rely on thermal-driven polymerization techniques that lack optical transparency, spatial, and temporal control.

[0131] Increasing the refractive index and crosslinking density of network polymers without changing the molecular weight or core structure of the monomers is challenging. Despite sporadic recent reports on sulfur- acetylene-based photopolymers, applications and research on scalable synthesis of high refractive index monomers and photopolymers are far less. Based on a general synthetic scheme developed for high refractive index thiol-acetylene photopolymers, here, a set of high refractive index, low viscosity acetylenic propargyl ethers that form miscible resins with multifunctional thiols is reported. Photopolymerization of these resin mixtures under mild conditions yields optically transparent films with refractive index values (nD) in various embodiments in the range of 1.60 to 1.75.

[0132] In various embodiments, compositions are provided. In certain embodiments, the composition comprises:

[0133] at least one monomer of Formula (I-A):

[0134]

[0135] and at least one monomer of Formula (II):

[0136]

[0137] wherein:

[0138] each occurrence of X is independently H or optionally substituted C 6-14 aryl;

[0139] each occurrence of Y1and Y2is independently -S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, -CH(SH)-, -CH[O-CH2-CH=CH2]-, or -CH[O-CH2-CºCH]-;

[0140] each occurrence of Y T1 and Y T2 is independently H, -SH, -CH=CH2, -CºCH, or optionally substituted C6-14 aryl;

[0141] each Z is independently S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, or -CH(SH)-;

[0142] each Z T is independently H, -SH, or -CH2SH;

[0143] each m1and m2is independently an integer in the range of 0 to 100; and

[0144] n is an integer in the range of 0 to 100.

[0145] The composition containing at least one monomer of Formula (I-A) and Formula (II) can be polymerized using any of the conditions described herein. Polymerization can be photopolymerization by exposing the monomer composition to UV and / or visible light.

[0146] In various embodiments, the polymerized composition has a refractive index of about 1.63 to about 1.69. In various embodiments, the polymerized composition has a refractive index of at least about, equal to, greater than about 1.60, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.70, 1.71, 1.72, 1.73, 1.74, or about 1.75.

[0147] In various embodiments, (Z) n -Z T contains at least one -SH moiety. In various embodiments, (Z) n -Z T contains at least two -SH moieties.

[0148] In various embodiments, the monomer of Formula (II) is selected from:

[0149]

[0150] In various embodiments, m1 is 1, Y1 is -S-, and YT1 is phenyl.

[0151] In various embodiments, at least one of (Y1) m1 and (Y2) m2 is linear.

[0152] In various embodiments, at least one of (Y1) m1 and (Y2) m2 comprises at least one of -CH(O-CH2-CH=CH2)- or -CH(O-CH2-C≡CH)-.

[0153] In various embodiments, at least one of (Y1) m1 and (Y2) m2 comprises at least two moieties independently selected from -CH(O-CH2-CH=CH2)- and -CH(O-CH2-C≡CH)-. In various embodiments, Y T1 and Y T2 is -C≡CH.

[0154] In various embodiments, the monomer of Formula (I-A) is selected from:

[0155]

[0156] The judicious use of various thiol-X click reactions in monomer synthesis not only allows for the incorporation of a large number of sulfur groups (sulfide groups), but also results in reactions with high yield and minimal byproducts. The monomers discussed here are synthesized starting from inexpensive and widely available starting materials, and the judicious use of thiol-epoxide and thiol-halide click reactions is employed (Scheme 1).

[0157] Scheme 1. General synthetic routes for the high refractive index multifunctional thiols (a) alkynyl sulfides (b) and alkynyl ethers (c) used in this study and their measured viscosity and refractive index (nD / 20°C) values.

[0158] The general strategy developed here also provides a high degree of freedom in the choice of backbone and polymerizable pendent groups. As can be seen from Scheme 2, the structures of the individual monomers differ in their core structure as well as the identity and location of the reactive functional groups. For example, the simplest alkynyl monomer 2a forms a low crosslinking density polymer only, as there is only one alkyne group, but has a low viscosity (32 cP) and high n (1.611) compared to the rest of the aryl-containing monomers 2c and 2d.

[0159] The dialkynyl monomer 2b has only sulfur in its backbone and no aryl groups. Despite the low refractive index (1.591), monomer 2b has the least steric hindrance and has a primary thioalkynyl functional group. Similarly, as the thiol monomers go from 1a to 1c, the number of secondary thiol groups increases with a corresponding increase in the refractive index. Specific material properties (such as T g , modulus, and hydrophobicity) are easily tuned while maintaining backbone flexibility and enhanced solubility. For example, the flexible sulfide linkages throughout the monomer design facilitate an increase in the refractive index without significantly increasing the initial resin viscosity or sacrificing solubility or other optical desirable features of a given monomer / resin.

[0160] Scheme 2. Structures of the high refractive index multifunctional thiols (A) and alkynes (B) used in this study and their measured viscosity and refractive index (nD / 20°C) values.

[0161] Since the minimum thiol functionality required for the formation of linear polymers via thiol-yne click reaction is 2, commercially available 2,2'-thiodiethanol thiol (la) with a refractive index (nD / 20°C) of 1.596 was used as the simplest dithiol. Trithiol (lb) and tetra thiol (lc) were obtained starting from the ring opening reaction of epichlorohydrin with 2-mercaptoethanol under mild reaction conditions following a previous procedure. In this way, 1 equivalent of 2-mercaptoethanol reacted quantitatively with epichlorohydrin in the presence of a catalytic amount of borax and selectively produced the mono-substituted product 1-chloro-3-(phenylthio)-2-propanol (CPTP), which further reacted with half equivalent of ethanedithiol to give the corresponding tetrahydroxy intermediate (TetraOH). Similarly, the trihydroxy intermediate (TriOH) was obtained by the reaction of two equivalents of 2-mercaptoethanol with epichlorohydrin in the presence of NaOH as base. After the reaction of TriOH and TetraOH with thiourea, the corresponding thiourea salts were hydrolyzed using a 50% NaOH solution to produce the corresponding TriSH and TetraSH with overall yields of 74% and 66%, respectively. Both monomers were isolated as colorless liquids with viscosities of 43 and 189 cP, respectively, and refractive index values (nD / 20°C) of 1.636 and 1.647, respectively. Since each alkyne functionality is difunctional (i.e. able to react twice), the simplest alkyne monomer 2a used in this study was prepared in two high-yield steps starting from the reaction of epichlorohydrin and sulfenol. In the second step, the 2° alcohol BPTP was deprotonated followed by alkylation with propargyl bromide and provided low viscosity (32 cP) 2a with a yield of 91% accompanied by a refractive index value (nD / 20°C) of 1.611. In contrast, monomer 2d was instead prepared in a single step via alkylation of dithiol la with propargyl chloride in the presence of KOH as base with a yield of 85%, a viscosity of 14 cP, and a refractive index value (nD / 20°C) of 1.591.

[0162] The first step of the synthesis of diacetylenic monomers 2c and 2d involves a borax-catalyzed selective thiol-epoxide ring-opening reaction of epichlorohydrin with a thiol. The reaction of epichlorohydrin with 1 equivalent of thiol provides the chloro intermediate 1-chloro-3-(phenylthio)-2-propanal (CPTP) as a colorless liquid in superior yield (>90%). In the presence of NaOH as a base, the chloro intermediate CPTP is further reacted with a high refractive index dithiol "core" such as 1,2-ethanedithiol (EDT) and 4,4'-thiobisbenzenethiol (TBT) to yield the corresponding alcohols EDTOH and TBTOH, respectively, as transparent viscous liquids in over 90% yield. Following this strategy, any high refractive index multifunctional thiol previously reported in the literature can be used to tune the final material properties according to the needs of the application under study. Finally, the diols are deprotonated with sodium hydride and then alkylated with 2 equivalents of propargyl bromide to yield the corresponding diacetylenic propargyl ethers 2c and 2d in high overall yield of 66% and 76%, respectively. Both 2c and 2d monomers are obtained as liquids with viscosity values of 171 cP and 732 cP, respectively, and in addition refractive index values (nD / 20°C) of 1.603 and 1.668, respectively. Overall, the synthesis of these intermediates of multifunctional thiols and diacetylenic monomers is easily scalable and can be stored for months without considering any special precautions.

[0163] EMBODIMENTS

[0164] The various embodiments of the present application can be better understood by reference to the following examples, which are offered by way of illustration. The scope of the application is not limited to the examples given herein.

[0165] General information for chemical synthesis: Commercial reagents were used without further purification. Thiol, epichlorohydrin, 2-mercaptoethanol, and ethanedithiol were purchased from Alfa Aesar. 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) was purchased from Chem-Impex International. Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiator was purchased from TCI America. Thiourea was purchased from Sigma-Aldrich. Reagent grade sodium hydroxide (NaOH) was purchased from Fisher Scientific. Anhydrous ethanol (200 proof) was purchased from Decon Labs Inc. 1 H and 13 C-NMR spectra (internal standard: 7.26 ppm, 1 H; 77.0 ppm, 13 C) were recorded on a Bruker 400 MHz spectrometer in CDC13.

[0166] Example 1: Preparation of 1,3-bis(2-mercaptoethylthio)-2-mercapto-propane (BMEMP, 1b)

[0167] 1,3-Bis(2-mercaptoethylthio)-2-mercapto-propane (BMEMP): To a 500 g dry round bottom flask equipped with a magnetic stir bar was added 17.8 g of 2-mercaptoethanol (228 mmol, 2.08 equiv) and diluted and homogenized with 69 mL (1.58 M) of anhydrous ethanol. To this solution was added 9.13 g (228 mmol, 2.09 equiv) of sodium hydroxide. After stirring for 10 min at room temperature, 10.1 g (109 mmol, 1 equiv) of epichlorohydrin was slowly added to the reaction mixture under a N2atmosphere. The mixture was heated to 50 °C and stirred for 1 hr. After this time, the reaction mixture was cooled to room temperature and 13.5 g of 36% hydrochloric acid (133 mmol, 1.22 equiv) was added to form a precipitate.

[0168] The precipitate was filtered and concentrated under reduced pressure to yield 22.05 g (95%) of 1,3-bis(2-hydroxyethylthio)-2-propanol (BHETP) as a light yellow viscous liquid which was used directly in the next step without further purification. In the second step, to a dry 500 g round bottom flask equipped with a reflux condenser and magnetic stir bar was added 22 g of BHETP (104 mmol, 1 equiv) and 28.9 g (379 mmol, 3.66 equiv) of thiourea and dissolved in 63.3 g (1.58 M) of 36% hydrochloric acid in water and homogenized. This solution was heated to 110 °C and stirred for 1 hr. After this time, the reaction was cooled to room temperature and 61.5 g (762 mmol, 7.35 equiv) of 50% NaOH aqueous solution was added under a N2atmosphere. The suspension was then stirred at room temperature for 24 hrs. After this time, 200 mL of toluene was added and the mixture was filtered via suction and then transferred to a separatory funnel. The organic layer was washed with 1 M hydrochloric acid solution, water and brine and then dried over sodium sulfate. The solution was filtered and concentrated under reduced pressure to yield 25.2 g (93%) of the title compound as a colorless liquid which was used as is without further purification.

[0169] BHETP: 1 H NMR (400 MHz, CDC13) δ = 5.05 (d, 1H), 4.77 (t, 2H), 3.72-3.67 (m, 1H), 3.55-3.50 (m, 4H), 2.70-2.55 (m, 8H); 13 C NMR (101 MHz, CDC13) δ = 70.9, 61.4, 38.2, 35.2.

[0170] BMEMP: 1H NMR (400 MHz, CDC13) δ = 2.95 - 2.71 (m, 15H), 1.79 - 1.72 (m, 3H); 13 C NMR (101 MHz, CDC13) δ = 49.0, 37.2, 36.2, 35.8, 28.8, 25.1, 24.9.

[0171] Example la: Alternative preparation of 1,3-bis(2-mercaptoethylthio)-2- mercaptopropane (BMEMP, lb)

[0172]

[0173] 1-Chloro-3-(hydroxyethylthio)-2-propanol (CHTEP) 2 : To a 500 mL round bottom flask, equipped with a magnetic stir bar, was added 21.2 mL (25.0 g, 0.27 mol, 1 equiv) of epichlorohydrin and 10.3 g (0.027 mol, 0.1 equiv) of borax and diluted with 135 mL of deionized water. To this suspension was added dropwise 19 mL (21.1 g, 0.27 mol, 1 equiv) of 2-mercaptoethanol over a 1 h period using an addition funnel. The reaction was allowed to stir at room temperature for 4 h. After this time, the mixture was extracted with CH2Cl2(3 x 100 mL). The combined organics were washed with water (~ 100 mL, 2X), brine (~ 50 mL, IX), dried over Na2S04, filtered and evaporated under reduced pressure to yield 43.0 g (93%) of the title compound CHTEP as a colorless viscous liquid which was used directly in the next step without further purification.1H NMR (400 MHz, CDC13) δ = 3.99 - 3.95 (m, 1H), 3.81 - 3.77 (m, 2H), 3.69 - 3.61 (m, 2H), 2.87 - 2.68 (m, 4H);13C NMR (101 MHz, CDC13) δ = 70.7, 61.3, 48.0, 36.4, 36.1.

[0174]

[0175] 1,3-bis-(hydroxyethylthio)-2-propanol (BHETP): The synthesis of BHETP is as follows. To a 1 L round bottom flask equipped with a magnetic stir bar was added 33.6 mL (37.2 g, 0.48 mol, 2.1 eq) of 2-mercaptoethanol and diluted with 318 mL of reagent grade ethanol. To this solution was added 19.0 g (0.48 mmol, 2.1 eq) of NaOH. After stirring at room temperature for 10 min, 21.0 g (0.23 mol, 1.0 eq) of epichlorohydrin was added slowly under a N2atmosphere. The resulting suspension was stirred at room temperature for 16 h. After this time, 27.5 g (0.27 mol, 1.2 eq) of 36% hydrochloric acid was added. The precipitate was filtered and concentrated under reduced pressure to yield 46.7 g (97%) of the title compound BHETP as a colorless viscous liquid which was used directly in the next step without further purification. 1 HNMR (400 MHz, CDC13) δ = 5.05 (d, 1H), 4.77 (t, 2H), 3.72-3.67 (m, 1H), 3.55-3.50 (m, 4H), 2.70-.55 (m, 8H);13C NMR (101 MHz, CDC13) δ = 70.9, 61.4, 38.2, 35.2.

[0176]

[0177] 1,3-bis-(hydroxyethylthio)-2-propanol (BHETP): The synthesis of BHETP is as follows. To a 1 L round bottom flask equipped with a magnetic stir bar was added 33.6 mL (37.2 g, 0.48 mol, 2.1 eq) of 2-mercaptoethanol and diluted with 318 mL of reagent grade ethanol. To this solution was added 19.0 g (0.48 mmol, 2.1 eq) of NaOH. After stirring at room temperature for 10 min, 21.0 g (0.23 mol, 1.0 eq) of epichlorohydrin was added slowly under a N2atmosphere. The resulting suspension was stirred at room temperature for 16 h. After this time, 27.5 g (0.27 mol, 1.2 eq) of 36% hydrochloric acid was added. The precipitate was filtered and concentrated under reduced pressure to yield 46.7 g (97%) of the title compound BHETP as a colorless viscous liquid which was used directly in the next step without further purification. a2SO4, filtered, and evaporated under reduced pressure to yield the title compound 1b as a colorless viscous liquid which was used without further purification.1H NMR (400 MHz, CDCI3) δ = 2.95 - 2.71 (m, 15H), 1.79 - 1.72 (m, 3H);13C NMR (101 MHz, CDCI3) δ = 49.0, 37.2, 36.2, 35.8, 28.8, 25.1, 24.9. HRMS (ESI): [M+CI]"calcd for C7H16S5CI: 295.9544, found: 295.9549. 1 H NMR (400 MHz, CDCI3) δ = 2.95 - 2.71 (m, 15H), 1.79 - 1.72 (m, 3H); 13 C NMR (101 MHz, CDCI3) δ = 49.0, 37.2, 36.2, 35.8, 28.8, 25.1, 24.9. HRMS (ESI): [M+CI]"calcd for C7H16S5CI: 295.9544, found: 295.9549. 16 S5CI of [M+CI] - calcd: 295.9544, found: 295.9549.

[0178] Example 1 b: Preparation of TetraOH

[0179] TetraOH: To a 500 mL round bottom flask, equipped with a magnetic stir bar, was added 4.46 mL (5.00 g, 0.053 mol, 1 equiv) of 1,2-ethanedithiol and diluted with 106 mL of ethanol. To this solution was added 4.24 g (0.106 mol, 2 equiv) of NaOH. After stirring at room temperature for 10 min, 18.1 g (0.106 mol, 2 equiv) of CHTEP was added slowly under a N2atmosphere. The resulting suspension was allowed to stir at room temperature for 16 h. After this time, 12.9 g (0.127 mol, 2.4 equiv) of 36% hydrochloric acid was added and the precipitated solid was filtered off. The filtrate was evaporated under reduced pressure to yield 18.1 g (94%) of the title compound as a colorless viscous liquid which was used directly in the next step without further purification. 1 H NMR (400 MHz, DMSO-d6) δ = 4.78 (bs, 4H), 3.73 - 3.67 (m, 2H), 3.35 (t, 4H), 2.74 - 2.54 (m, 6H); 13 C NMR (101 MHz, DMSO-d6) δ = 70.4, 60.91, 37.7, 37.2, 34.8, 32.3.

[0180]

[0181] Example 1 c: Preparation of monomer 1 c

[0182] 1c: To a 500 mL round bottom flask, equipped with a reflux condenser and a stir bar, was added 18 g (0.049 mol, 1 equiv) TetraOH and dissolved in 40.2 g (0.397 mol, 8 equiv) of 36% aqueous hydrochloric acid. To this solution was added 18.1 g (0.238 mol, 4.8 equiv) of thiourea and heated to 110 °C for 1 h. After this time, the flask was allowed to cool to room temperature and 19.9 g (0.496 mol, 10 equiv) of 50% aqueous NaOH was added under a N2atmosphere. The suspension was then allowed to stir at room temperature for 24 h. After this time, 500 mL of toluene was added and the mixture was transferred to a separatory funnel, washed with 1 M hydrochloric acid solution (250 mL, IX), water (~ 150 mL, IX), brine (100 mL, IX), dried over Na2S04, filtered, and evaporated under reduced pressure to yield 16.2 g (76%) of the title compound 1c as a colorless viscous liquid which was used without further purification. 1 H NMR (400 MHz, CDC13) δ = 2.96 - 2.69 (m, 22H); 13 C NMR (101 MHz, DMSO-d6) δ = 51.6, 48.9, 37.1, 36.1, 35.7, 28.8, 28.7, 28.2, 25.1, 24.9; HRMS (ESI): C 12 H 26 S8Li of [M+Li] + Calculated: 432.9960, Found: 432.9990.

[0183] Example 1d: Preparation of 1,3-bis-(phenylthio)-2-propanol (BPTP)

[0184]

[0185] 1,3-bis-(phenylthio)-2-propanol (BPTP): To a 250 mL round bottom flask equipped with a magnetic stir bar was added 16 mL (157 mmol, 2.2 eq) of thiophenol, which was then diluted with 230 mL of toluene (0.3 M, w.r.t. epichlorohydrin). To this solution was added 23 mL of DBU (154 mmol, 2.2 eq) under a N2atmosphere and stirred at room temperature for 10 min. After this time, 5.5 mL of epichlorohydrin (70.3 mmol, 1.0 eq) was added dropwise and the reaction vessel was allowed to stir at room temperature for 16 h. After this time, the volatiles were removed under reduced pressure. The residue was diluted with 500 mL of DCM, washed with 1 M HC1 (100 mL), water (100 mL), brine (50 mL), dried over anhydrous Na2S04, filtered, and concentrated under reduced pressure to yield the crude product as a light yellow liquid. Purification by silica gel column chromatography using 50% EtOAc in hexanes as the eluent afforded BPTP (17.1 g, 88% yield) as a colorless viscous liquid. 1 H NMR (400 MHz, Chloroform-d): δ 7.36-7.33 (m, 4H), 7.29-7.24 (m, 4H), 7.22-7.18 (m, 2H), 3.86-3.79 (m, 1H), 3.20 (dd, J = 13.8, 5.0 Hz, 2H), 3.05 (dd, J = 13.8, 7.2 Hz, 2H), 2.74 (d, 1H). 13 CNMR (101 MHz, Chloroform-d, 25 °C): δ 135.1, 129.9, 129.1, 126.7, 68.2, 40.1.

[0186] Example 1e: Preparation of 1-chloro-3-(phenylthio)-2-propanol (CPTP)

[0187]

[0188] 1-chloro-3-(phenylthio)-2-propanol (CPTP): To a 500 mL round bottom flask equipped with a magnetic stir bar was added 50.0 mL (0.64 mol, 1 eq) of epichlorohydrin and 24.4 g (0.064 mol, 0.1 eq) of borax, which was diluted with 320 mL of deionized water. To this suspension was added 65 mL (0.64 mol, 1 eq) of thiophenol dropwise over a period of 1 h using an addition funnel. The reaction was allowed to stir at room temperature for 4 h. After this time, the mixture was extracted with CH2Cl2(3 x 100 mL). The combined organic extracts were washed with water (~ 100 mL, 2X), brine (~ 50 mL, IX), dried over Na2S04, filtered, and evaporated under reduced pressure to yield 99.3 g (96%) of the title compound CPTP as a colorless liquid, which was used directly in the next step without further purification.1 H NMR (400 MHz, CDC13) δ = 7.42-7.39 (m, 2H), 7.33-7.29 (m, 2H), 7.26-7.22 (m, 1H), 3.97-3.90 (m, 1H), 3.72-3.64 (m, 2H), 3.20-3.06 (m, 2H), 2.62 (d, 1H); 13 C NMR (101 MHz, CDC13) δ = 134.7, 130.3, 130.1, 129.4, 127.1, 69.7, 48.1, 38.4.

[0189] Example If: Alternative preparation of 1,2-ethanedithiol-based intermediate diol (EDTOH)

[0190]

[0191] 1,2-ethanedithiol-based intermediate diol (EDTOH): To a 500 mL round bottom flask, equipped with a magnetic stir bar, was added 4.46 mL (5.00 g, 53.08 mmol, 1 equiv) of 1,2-ethanedithiol and diluted with 106 mL of ethanol. To this solution was added 4.25 g (106.16 mmol, 2 equiv) of NaOH. After stirring at room temperature for 10 min, 21.5 g (106.16 mmol, 2 equiv) of CPTP was added slowly under a N2atmosphere. The resulting suspension was stirred at room temperature for 24 h. After this time, the ethanol was removed under reduced pressure to yield a crude residue which was diluted with EtOAc (~ 500 mL), washed with 1 N HC1 (~ 150 m, 2X), water (~ 150 mL, IX), and brine (~ 150 mL, IX). The combined organics were dried over Na2S04, filtered, and concentrated under reduced pressure to yield a yellow viscous liquid which was submitted to silica gel column chromatography using 60% EtOAc / Hex as eluent. Evaporation of the fractions containing the desired material yielded 22.1 g (97%) of the title compound EDTOH as a colorless viscous liquid. 1 H NMR (400 MHz, CDC13) δ = 7.40-7.37 (m, 4H), 7.31-7.26 (m, 4H), 7.23-7.19 (m, 2H), 3.84-3.78 (m, 2H), 3.16-3.11 (m, 2H), 3.06-3.01 (m, 2H), 2.84-2.78 (m, 2H), 2.74 (m, 4H), 2.68-2.62 (m, 2H); 13 C NMR (101 MHz, CDC13) δ = 135.2, 130.1, 129.3, 126.8, 69.1, 40.3, 38.2, 32.9.

[0192] Example 1g: Preparation of 4,4'-thiobisphenylthiol-based intermediate diol (TBTOH)

[0193]

[0194] 4,4'-thiobisphenylthiol-based intermediate diol (TBTOH): To a 500 mL round bottom flask equipped with a magnetic stir bar was added 5.00 g (19.97 mmol) of 4,4'-thiobenzenethiol and diluted with 200 mL of toluene. To this suspension was added 6.08 g (39.93 mmol, 2 equiv) of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). After stirring at room temperature for 10 min, 8.09 g (39.93 mmol, 2 equiv) of CPTP was added slowly under a N2atmosphere. The resulting suspension was heated to 90 °C for 16 h. After this time, the reaction was allowed to cool to room temperature and the toluene was removed under reduced pressure to give a crude residue which was diluted with EtOAc (~ 250 mL), washed with 1 N HC1 (~ 100 mL, 2X), water (~ 100 mL, IX), and brine (~ 50 mL, IX). The combined organics were dried over Na2S04, filtered, and concentrated under reduced pressure to yield a yellow viscous liquid which was submitted to silica gel column chromatography using 60% EtOAc / Hex as eluent. Evaporation of the fractions containing the desired material gave 10.6 g (91%) of the title compound TBTOH as a light yellow viscous liquid. 1 H NMR (400 MHz, CDC13) δ = 7.38-7.35 (m, 4H), 7.31-7.26 (m, 8H), 7.24-7.19 (m, 6H), 3.88-3.83 (m, 2H), 3.24-3.19 (m, 4H), 3.10-3.04 (m, 4H), 2.80 (bs, 2H)); 13 C NMR (101 MHz, CDC13) δ = 135.0, 134.7, 133.9, 131.6, 130.4, 130.1, 129.3, 126.9, 68.2, 40.2, 39.9.

[0195] Example 1h: Preparation of 1,3-bis-(n-propylthio)-2-propanol (BPrTP)

[0196]

[0197] 1,3-Bis-(n-propylthio)-2-propanol (BPrTP): To a 250 mL round bottom flask equipped with a magnetic stir bar was added 7.8 mL (8.6 g, 113.5 mmol, 2.1 equiv) of n-propyl mercaptan and diluted with 75 mL of reagent grade ethanol. To this solution was added 4.54 g (113.5 mmol, 2.1 equiv) of NaOH. After stirring at room temperature for 10 min, 5.0 g (54.0 mmol, 1.0 equiv) of epichlorohydrin was added slowly under a N2atmosphere. The resulting suspension was heated to 50 °C for 1 h. After this time, the flask was allowed to cool to room temperature and 6.4 g (64.8 mmol, 1.2 equiv) of 36% hydrochloric acid was added. The precipitate was filtered and concentrated under reduced pressure to yield 10.2 g (91%) of the title compound as a colorless liquid which was used directly in the next step without further purification. 1 H NMR (400 MHz, Chloroform-d) δ 3.82 - 3.76 (m, 1H), 2.76 (dd, J = 13.6, 4.7 Hz, 2H), 2.62 (dd, J = 13.6, 7.5 Hz, 2H), 2.53 (dd, J = 7.7, 7.0 Hz, 4H), 1.64 - 1.57 (m, 4H), 0.98 (t, J = 7.3 Hz, 6H); 13 C NMR (101 MHz, CDC13) δ = 68.8, 38.4, 34.8, 23.2, 13.6.

[0198] Example 1i: Preparation of 1,3-Bis-(n-propylthio)-2-propanethiol (3a)

[0199]

[0200] 1,3-bis-(n-propylthio)-2-propanethiol (3a): To a 250 mL round bottom flask equipped with a reflux condenser and a stir bar was added 10.2 g (48.95 mmol, 1 eq) of BPrTP and dissolved in 9.9 g (97.9 mmol, 2 eq) of 36% aqueous hydrochloric acid. To this solution was added 5.6 g (73.42 mmol, 1.5 eq) of thiourea and heated to 110 °C for 1 h. After this time, the flask was cooled to room temperature and 9.8 g (122.4 mmol, 2.5 eq) of 50% aqueous NaOH was added under a N2atmosphere. The suspension was then stirred at room temperature for 24 h. After this time, 200 mL of toluene was added and the mixture was transferred to a separatory funnel, washed with 1 M hydrochloric acid solution (150 mL, 1X), water (~100 mL, 1X), brine (50 mL, 1X), dried over Na2S04, filtered, and evaporated under reduced pressure to yield the crude product which was purified by silica gel column chromatography using 10% EtOAc / hexanes as eluent to yield 8.4 g (77%) of the title compound 3a as a colorless liquid. 1 H NMR (400 MHz, Chloroform-d) δ 2.95 - 2.81 (m, 4H), 2.56 - 2.51 (m, 4H), 1.80 (t, J = 8.1 Hz, 1H), 1.65 - 1.58 (m, 4H), 1.02 - 0.97 (m, 6H); 13 CNMR (101 MHz, CDC13) δ = 48.3, 39.8, 36.1, 35.1, 33.5, 28.5, 23.3, 23.2, 13.7, 13.6.

[0201] Example 2: Preparation of 1,2-ethanedithiol-based diallyl ether (EDTDAE)

[0202] 1,2-ethanedithiol-based diallyl ether (EDTDAE): EDTDAE was prepared following the procedure reported previously. Briefly, in a dry 500 g round bottom flask, equipped with a magnetic stir bar, 50 mL (640 mmol, 1 equiv) of epichlorohydrin and 24.4 g (64 mmol, 0.1 equiv) of borax were added to 320 mL (2 M) of deionized water. 65 mL (635 mmol, 1 equiv) of thiophenol was added dropwise to the stirred solution using an addition funnel over 1 h. The reaction was allowed to proceed at room temperature for 4 h. The mixture was then extracted with CH2Cl2(3 x 100 mL) and then washed with water (200 mL) and brine (50 mL). The combined extracts were dried over Na2SO4and concentrated in vacuo to obtain 99.3 g of 1-chloro-3-(phenylthio)-2-propanol (CPTP) (96% yield). No further purification was performed and the compound was used as is. In the second step, a 500 mL round bottom flask, equipped with a magnetic stir bar, was charged with 4.46 mL (5.00 g, 53.08 mmol, 1 equiv) of 1,2-ethanedithiol and diluted with 106 mL of ethanol. To this solution was added 4.25 g (106.16 mmol, 2 equiv) of NaOH. After stirring at room temperature for 10 min, 21.5 g (106.16 mmol, 2 equiv) of CPTP was added slowly under N2atmosphere.

[0203] The resulting suspension was stirred at room temperature for 24 h. After this time, the ethanol was removed under reduced pressure to give a crude residue which was diluted with EtOAc (~ 500 mL) and washed with 1 N HC1 (~ 150 mL, 2X), water (~ 150 mL, IX) and brine (~ 150 mL, IX). The combined organics were dried over Na2S04, filtered, and concentrated under reduced pressure to yield a yellow viscous liquid which was submitted to silica gel column chromatography using 60% EtOAc / hexanes as eluent. The fractions containing the desired material were evaporated to yield 22.1 g (97%) of 1,2-ethanedithiol diol (EDT-OH) as a colorless viscous liquid. In the last step, a 500 mL round bottom flask equipped with a magnetic stir bar was charged with 10.0 g (23.44 mmol, 1 equiv) of EDT-OH and diluted with 117 mL of anhydrous THF. The flask was cooled to 0 °C and 1.69 g (70.31 mmol, 3 equiv) of NaH was added portionwise. After stirring at room temperature for 30 min, 8.50 g (70.31 mmol, 3 equiv) of allyl bromide was added followed by 0.39 g (2.34 mmol, 0.1 equiv) of potassium iodide. The resulting solution was stirred at room temperature for 16 h. After this time, the reaction mixture was diluted with EtOAc (~ 300 mL) and washed with 1 N HC1 (~ 100 mL, 2X), water (~ 100 mL, IX) and brine (~ 50 mL, IX). The combined organics were dried over Na2S04, filtered, and concentrated under reduced pressure to give a crude product as a light yellow liquid which was purified by silica gel column chromatography eluting with (30% EtOAc / hexanes). The fractions containing the product were evaporated under reduced pressure to yield 8.3 g (71%) of the title compound (EDTDAE) as a light yellow viscous liquid. CPTP: 1 H NMR (400 MHz, CDC13) δ = 7.42-7.39 (m, 2H), 7.33-7.29 (m, 2H), 7.26-7.22 (m, 1H), 3.97-3.90 (m, 1H), 3.72-3.64 (m, 2H), 3.20-3.06 (m, 2H), 2.62 (d, 1H); 13 C NMR (101 MHz, CDC13) δ = 134.7, 130.3, 130.1, 129.4, 127.1, 69.7, 48.1, 38.4.

[0204] EDT-OH: 1 H NMR (400 MHz, CDC13) δ = 7.40-7.37 (m, 4H), 7.31-7.26 (m, 4H), 7.23-7.19

[0205] (m, 2H), 3.84-3.78 (m, 2H), 3.16-3.11 (m, 2H), 3.06-3.01 (m, 2H), 2.84-2.78 (m, 2H), 2.74 (m, 4H), 2.68-2.62 (m, 2H); 13 C NMR (101 MHz, CDC13) δ = 135.2, 130.1, 129.3, 126.8, 69.1, 40.3, 38.2, 32.9.

[0206] EDTDAE: 1 H NMR (400 MHz, CDC13) δ = 7.39-7.36 (m, 4H), 7.31-7.26 (m, 4H), 7.21-7.17 (m, 2H), 5.99-5.83 (m, 2H), 5.25-5.13 (m, 4H), 4.09-4.00 (m, 4H), 3.67-3.61 (m, 2H), 3.18-3.16 (m, 4H), 2.87-2.73 (m, 8H); 13 C NMR (101 MHz, CDC13) δ = 136.2, 134.7, 129.6, 129.1, 126.4, 117.6, 77.8, 71.2, 37.0, 35.6, 33.2, 33.1.

[0207] Example 3: Films for holographic recording

[0208] Preparation of films for holographic recording: Polycaprolactone-block- polytetrahydrofuran-block-polycaprolactone (Mn ~ 2000), 1,6-diisocyanatohexane and 2-(allyloxymethyl)-2-ethyl-1,3-propanediol were mixed together in vials according to Table 3 to obtain linear polyurethanes with different allyl side chain content.

[0209] Table 3. Composition table of linear matrix.

[0210]

[0211] a ) Allyl content = moles of TMPAE / (moles of TMPA + moles of polyol 2000). HDI = 1,6-hexane diisocyanate (diisocyanato-1,6-hexane).

[0212] Then, the vials were placed in an oven at 70 °C overnight to perform the polymerization. After that, a polymer solution was prepared using acetone as solvent, controlling the concentration at 20% w / w (determined in relation to the mass of polymer binder in relation to the sum of polymer and solvent); at the same time, the thiol-ene writing monomers were also dissolved in the solution in stoichiometric ratio, as can be seen in Table 4.

[0213] Table 4. Composition table of written monomers. a

[0214]

[0215] a) Thiol-ene content = Thiol-ene monomer mass / (polymer matrix mass + thiol-ene mass)

[0216] 100 μL of the solution for each membrane was applied to a glass slide (Fisherbrand 2.54 cm × 7.62 cm) using a ZAA2300 automatic membrane applicator while maintaining the temperature at 45 °C. Finally, the membrane was held on a platform at 45 °C for 2 minutes.

[0217] The refractive indices of linear matrices with various allyl contents obtained according to various implementation methods are summarized in Table 5.

[0218] Table 5. Refractive index of linear matrices with different allyl contents.

[0219] Allyl content 0 mol % 10 mol % 30 mol % 50 mol % n f (486.2nm) a ]]> 1.480 ± (3 x 10 -4 )]]> 1.481 ± (3 x 10 -4 )]]> 1.482 ± (6 x 10 -4 )]]> 1.485 ± (6 x 10 -4 )]]> n d (589.3nm) a ]]> 1.474 ± (6 x 10 -4 )]]> 1.475 ± (5 x 10 -4 )]]> 1.476 ± (1 x 10 -4 )]]> 1.478 ± (5 x 10 -4 )]]> n c (657.4 nm) a ]]> 1.471 ± (4 x 10 -4 )]]> 1.473 ± (9 x 10 -4 )]]> 1.473 ± (8 x 10 -4 )]]> 1.476 ± (6 x 10 -4 )]]> Abbe number b ]]> 56.4 57.2 54.8 55.6

[0220] a) All refractive indices are averaged from three samples. b) Abbe number = (n d –1) / (n f –n c )

[0221] The molecular weights of the linear polymer matrices according to some embodiments are listed in Table 6.

[0222] Table 6. Molecular weight of linear polymer matrices. a

[0223] Allyl content 0 mol % 10 mol % 30 mol % 50 mol % M n ]]> 1.7 x 10 4 ]]> 1.5 x 10 4 ]]> 1.8 x 10 4 ]]> 1.7 x 10 4 ]]> M w ]]> 2.2 x 10 4 ]] 1.7 x 10 4 ]]> 2.5 x 10 4 ]]> 2.3 x 10 4 ]]> PDI 1.3 1.1 1.4 1.4

[0224] a Molecular weight was measured twice, and the average of the two tests was used. PDI is calculated using the average molecular weight.

[0225] Example 4: Properties of the Recorded Hologram

[0226] Holographic recording and dynamic range (Δn) determination: In Figure 11 The transmission hologram was recorded in the two-beam interferometer setup shown. A power-matched recording beam was generated using a spatially filtered wavelength-stabilized 405nm laser diode (Ondax, 40mW), with a total intensity of ~16mW / cm². 2Two grating periods of 0.5 pm and 1 pm were used in the experiment, achieved by recording at external recording half-angles of 23.9° and 11.2°, respectively. In addition, the hologram development during recording was simultaneously probed via a 633 nm He-Ne laser (Thorlabs) roughly aligned at the Bragg reconstruction angle. After writing, a sample rotation from -15° to 15° was applied at a speed of 0.2° / s to obtain the angular selectivity of the recorded hologram; the diffraction efficiency (DE) versus time was recorded during this rotation, which is defined as the quotient of the diffracted power and the total power (transmitted and diffracted). The sets with monomer loadings of 33 w% and 43 w% were exposed for 15 s, while the set with 20 w% was exposed for 45 s; thus, the best diffraction efficiency was achieved for each sample. Finally, the angular selectivity was fitted with the Kogelnik coupled-wave theory to obtain the refractive index modulation (An) and the film thickness.

[0227] Film profile determination: Film surface roughness and thickness measurements were performed using a stylus profilometer from Dektak XT. Thickness was obtained via a scan from a blank area of the glass substrate to an area covered with the polymer film. Film roughness was analyzed with a scan within the film area.

[0228] Shelf-life evaluation of written monomers: Trithiol and diene monomers were mixed in a vial in stoichiometric ratios; 3 w% of the photoinitiator diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) was added according to the monomer mass and homogenized using a vortex mixer. The mixture was then cast onto a clean glass slide (Fisher Scientific) and clamped with the same glass slide using a binder clip with a 250 pm thick polyethylene terephthalate spacer. The retention of double bonds over time was monitored using a Thermo Scientific Nicolet iS50 FT-IR spectrometer in the near-IR range by calculating the ratio between the double bond peak area (~6113 cm -1 ) and the total peak area (5570 cm -1 -6180c m-1 ) over time. The percentage of double bond retention was obtained by comparing the ratio after different times with the initial ratio.

[0229] Stability evaluation of holograms and non-recorded films: Three stabilities were evaluated in this experiment. The empty film (EF) stability was determined using the ratio between the dynamic range of a hologram recorded at a specific time after film preparation and the dynamic range of a hologram recorded immediately after film preparation. The dynamic range obtained from the reading of the same hologram at different times was compared to the initial dynamic range to reveal the stability of the holographic recording film (HF) and the flood-cured holographic film (FCHF). The flood-curing was performed by exposing the sample under a 27W 405nm LED lamp for 3 minutes.

[0230] Haze measurement of holograms and films: The percent transmittance haze was measured using a haze meter from BYK named Haze-gard i, which measures an area of 18mm 2 ) for each sample. Three samples were prepared for each composition, while each sample was measured three times at different points. Therefore, the average value with standard deviation was obtained and plotted in the figures.

[0231] Microscopic characterization of gratings in holograms: A three-dimensional 3100 atomic force microscope (AFM) manufactured by Digital Instruments was applied to obtain the height profile within the hologram at a scan rate of 0.5003 Hz for a 10 pm scan size. Hitachi SU3500 scanning electron microscope (SEM) of the hologram was analyzed by Hitachi SU3500 SEM.

[0232] Refractive index (RI) measurement: The refractometer from Anton Paar was used to determine the refractive index at the wavelengths of Fraunhofer C, D and F lines (656.3 nm, 589.3 nm and 486.1 nm, respectively). The Abbe number can then be calculated according to the definition. The refractive index of the writing monomer and the linear polymer matrix was measured directly. The thiol-ene writing monomer was mixed stoichiometrically with 3% w / w% TPO and exposed under a 405 nm LED lamp for 3 minutes to form a polymer. After that, the RI of the polymer was measured to represent the RI of the written polymer formed in the bright fringes during recording.

[0233] Reflection hologram recording: The films for reflection holograms were prepared with multiple doctor blading to obtain a thick film of around 25 pm. The reflection holograms were recorded in a single-beam Denisyuk configuration with a laser intensity of 131 mW / cm 2 , an incident angle of 10° Figure 3 , after a flood-curing process under a 405 nm LED for 3 minutes; then the transmission spectrum was measured at the same recording point using a high-resolution spectrometer (Avantes AvaSpec-ULS4096CL-EVO).

[0234] The terms and expressions used herein are 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 recognizing that various modifications are possible within the scope of the embodiments of the present application. Thus, it should be understood that although the present application has been specifically disclosed by embodiments and optional features, modification and variation of the specific embodiments and features disclosed can be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of the embodiments of the present application.

[0235] Example 5: Photopolymerization of Thiol-Yne Monomers and Real-Time FTIR Kinetics

[0236] Without being bound by theory, the generally accepted mechanism of thiol-yne photopolymerization is shown in Scheme 2. Mechanistically, the radical-mediated thiol-yne reaction is analogous to the radical-mediated thiol-ene reaction, where each alkyne group reacts twice with a thio radical. This additional step involves the reaction of the vinyl sulfide intermediate formed in the first step with a second thio radical, followed by chain transfer to a thiol to form another sulfur linkage. In the kinetic analysis, each terminal alkyne group is considered to be bifunctional, thus resulting in a network polymer, and both the thiol and alkyne monomers require at least two functional groups.

[0237] Scheme 2: Mechanism of radical-mediated thiol-yne click reaction showing sequential addition and hydrogen abstraction steps.

[0238] Table 7: Physical and optical properties of thiol-yne based photopolymer networks.

[0239] Thiol-yne resins were formulated by mixing thiol and alkyne monomers with a thiol:alkyne functional group molar ratio of 2: 1 with ~1 wt% 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) and photopolymerized by irradiation with a 405 nm LED lamp at 30 mW / cm 2 a determined by rotational rheometer, b refractive index indicated by Fraunhofer D-line (589 nm), c determined by DSC.

[0240] To investigate the photopolymerization kinetics, resin mixtures with stoichiometric amounts of thiol and alkyne (Yne:SH = 1 :2) groups were formulated from the synthesized thiol and alkyne monomers (Table 7). All compositions formed miscible resin mixtures with low viscosity (>473 cP) and the conversion was monitored with real-time Fourier transform infrared (FTIR) spectroscopy. Upon irradiation at 30 mW / cm 2 of 405 nm, both the thiol and alkyne groups reacted rapidly, as indicated by the corresponding decrease in the thiol (2570 cm -1 ) and alkyne (2120 cm -1The disappearance of the peak is shown. However, it was found that the reactivity of thiols and alkynes varies significantly with the steric and electronic properties of the monomers and with resin viscosity, thus having a huge impact on polymerization kinetics. For example, in compositions A1-A4, monomer 1a, which contains only 1° thiols, shows different reactivity across alkyne monomers 2a-2d, indicating the influence of viscosity and steric effects.

[0241] It is noteworthy that the highly flexible diyne monomers 2b and 2a achieved thiols and alkynes conversions of up to 80% within 5 minutes, compared to only ~70% for the remaining diyne monomers 2c and 2d. Figure 16A The significant difference in polymerization kinetics of 2b is presumably due to its lower steric hindrance and its ability to form low-viscosity resin mixtures. However, the influence of second-order interactions, such as π-π stacking in the aryl-containing diyne monomers 2a, 2c, and 2d, cannot be ruled out. While all compositions containing 2b showed high conversion rates (~80%) of thiols and alkynes, all other compositions containing aryl-containing alkyne monomers were found to have significantly lower conversion rates. Unbound from theory, this significant difference in conversion rates suggests the influence of steric hindrance and resin viscosity, which restrict movement and hinder the accessibility of the reaction between thiols and alkynes after network formation. Figures 16A-16C ).

[0242] Furthermore, in compositions containing 1a, the higher concentrations of vinyl sulfides in A3 and A4 compared to A1 and A2 clearly indicate that thiols cannot, and even do not react with, vinyl sulfides, which are typically several times more reactive than their corresponding alkynes. Figure 21A The inactivity of vinyl sulfides in this system can be attributed to steric hindrance following the reaction of a thiol. The reactivity of polyfunctional thiols is highly influenced by the properties of the thiol (i.e., 1° or 2°) and its relative position. As expected, the conversion of composition 2b, containing monomers 1b and 1c with 2° thiols, drops to <80%. As seen in the kinetic rate plot, other alkyne monomers 2a, 2c, and 2d, containing large core structures, achieve conversions of 60% or lower in all cases. Figures 16B-16C This difference is thought to be due to the limited mobility and potentially lower reactivity of the shorter 2° thiol group (which is difficult to access after the primary thiol of the same monomer has reacted). As previously mentioned, the increased steric hindrance of the 2° thiol increases the activation energy of the chain transfer step, leading to a significant decrease in the reaction rate. Although a similar trend in the reactivity of 1°, 2°, and 3° thiols is observed in thiol-olefin photopolymer systems under lower initiation conditions due to steric factors. 14 To better understand the reactivity of 2° thiols with alkynes, a model 2° thiols were synthesized according to the general synthetic scheme described in this paper. Figure 22). The reactivity differences of alkynes towards 1° and 2° thiols were analyzed using hexanethiol (HT) and 3a as model 1° and 2° thiols, respectively. Real-time FT-IR kinetics of compositions M1 and M2 containing stoichiometric amounts of 3a and HT with 2a (i.e., SH:Yne = 2:1) clearly showed that the reaction rate of 2° thiols is slower than 1° thiols Figures 23A-23B ). Since 2° thiols have a large structural similarity with 1b and 1c, the lower conversion of the model 2° thiols clearly indicates that steric bulk and position have a significant influence on the reactivity of thiols-alkynes.

[0243] In addition, in some cases, it was found that the functional group conversion of the alkyne at a given time was slightly higher than that of the thiol. This behavior reflects the reaction of the vinyl sulfide formed by the initial thiol-alkyne reaction, and is consistent with the previous observation that the addition of thiols to alkynes leads to the formation of vinyl sulfides, which reacts significantly slower than between thiols and vinyl sulfides. This difference can also be attributed to chain growth addition mechanisms (i.e., homopolymerization or copolymerization) consuming either the alkyne or the vinyl sulfide functional groups. Photopolymerization was also performed at high temperature of 60 °C and under non-stoichiometric conditions (Yne:SH = 1:3). Although a slight increase in alkyne conversion was observed under non-stoichiometric conditions, no significant change in conversion was observed at this high temperature, indicating that the resin viscosity has little effect on the conversion and confirming that 2° thiols cannot effectively participate in the reaction, even at high temperatures.

[0244] Example 6: Thermo-mechanical properties of high n thiol-alkyne photopolymers

[0245] One of the key features of the thiol-alkyne reaction relative to similar thiol-ene click reactions is the high crosslinking density of polymers resulting from the reaction of one alkyne with two thiol moieties, which is higher than the corresponding thiol-ene composition. As mentioned above, all compositions form fully miscible resin mixtures with low viscosity (>473 cP) and form optically clear films after irradiation with 405 nm light at 30 mW / cm 2 Optically clear films were formed between the glass slides after irradiation. Although the conversion was low, especially for resin compositions containing diynes 2c and 2d and polythiols 1b and 1c, all of which were significantly higher than the gel point conversion and formed mechanically robust films. In addition, as previously pointed out, step-growth polymerization systems with stoichiometric equilibrium, in which the initial addition rate is slower than the subsequent addition rate (i.e., kP,2 / kP,1>1), have lower gel point conversions than the Flory-Stockmayer prediction. One of the key features of step-growth thiol-ene and thiol-alkyne networks is their relatively narrow glass transition region, which is caused by the formation of a uniform network.

[0246] A similar trend was observed in the thiol-acetylene network formed here, indicating a relatively uniform network formation. However, the tanδ curves of the network formed from dithiols and diacetylenes were found to be slightly wider than those of the previously reported dithiol-diacetylene network. Figures 17A-17C This difference is thought to be due to the formation of a non-uniform network resulting from the presence of two different thiol functional groups under different chemical environments. The glass transition temperatures of all network polymers were measured by DMA, except for compositions A1, B1, and C1—which were measured by DSC analysis due to the difficulty in preparing large samples. Table 7 lists the glass transitions obtained from various thiol-alkyne compositions. As expected, the photopolymers obtained from compositions A2, B2, and C2 exhibited higher T values ​​between 0°C and 19°C, based on higher conversion rates. g The components A1, B1, and C1 exhibit a temperature below -30°C (T0). g This is because these components primarily form linear polymers.

[0247] However, all other compositions containing diyne 2c and 2d were observed in T. g The value increased. As expected, polymers A4, B4, and C4 with rigid thiobenzenethiol (TBT) cores showed better performance than A3, B3, and C3 with ethylenedithiol (EDT) cores (whose T... g Values ​​in the range of -18 to -6℃ are higher than T. g Values ​​(-3.8 to 2.9 °C). Although the conversion rates of thiols and alkynes in these compositions are significantly higher than the gel point, the lower overall conversion rate limits the expected crosslinking density and Tg. g Value. Therefore, the wide range of thermomechanical properties of these photopolymer systems formed from diynes and polyfunctional thiols are evaluated, where T g The value ranges from -18 to 19℃. It is around [a certain value] with a high refractive index and low T [temperature]. g The material is well-suited for applications in optical and ophthalmic implants. Furthermore, each sample exhibits a similar transition from a vitreous state (where the elastic modulus is greater than 1 GPa) to a rubbery state (where the modulus is significantly lower).

[0248] Example 7: Refractive index of thiol-acetylene photopolymer:

[0249] Due to the high intrinsic atomic refraction, sulfur-containing polymers are expected to exhibit high refractive indices. Thus, the increase in the refractive index of the photopolymer formed from the thiol-x polymerization is a direct result of the incorporation of sulfide moieties in the network. One important feature of thiol-yne photopolymerization is that it allows the introduction of a large number of sulfur bonds compared to the corresponding thiol-ene composition. This feature of the thiol-yne reaction is attributed to the fact that one alkyne can react with two thiol groups, which is not possible for the thiol-ene system and results in an increase in the amount of sulfur in the system. With this approach, it is easy to obtain photopolymers with large changes in refractive index by simply switching the monomer functionality from vinyl to the corresponding alkyne reactive group.

[0250] As can be seen from Table 7, each combination of the synthesized thiol and alkyne monomers resulted in a photopolymer with a refractive index n D (20 °C) spanning a range of 0.04. These RI values at low conversion (about 60%) are already higher than those previously reported for similar thiol-ene systems. The high refractive index values exhibited by these network polymers are a direct result of the monomer core design incorporating substituents with high molar refraction. Thus, the refractive index of the aromatic dithiol core in 2d is increased by 0.03 compared to the alkyl counterpart 2c. The use of an excess of thiol, i.e. non-stoichiometry, in the resin composition can improve the polymer refractive index as well as limit the conversion of the reagent (i.e. alkyne monomer) by reducing diffusion limitations. However, an attempt to improve the polymer refractive index through the non-stoichiometric combination of 1b and 1c with 2d (thiol-yne, 3:1) resulted in a negative effect, decreasing the refractive index by 0.02.

[0251] A reasonable explanation for this difference is that the free thiol contributes less to the improvement of the refractive index compared to the sulfide moieties produced by the thiol-yne click reaction. This behavior is evident by the significant change in the refractive index (0.08) observed for composition B2 (dithiol 1b and alkyne monomer 2b) during the polymerization process. Upon exposure to 405 nm light at an intensity of 30 mW / cm2, the refractive index of the resin changed from 1.60 to 1.68 within 5 min, indicating the formation of a large number of sulfide bonds due to high conversion. Since there are no aromatic groups present in this resin system, the concentration of sulfur bonds gives a direct measure of the polymer refractive index. It is worth noting that the measured polymer refractive index shows a linear relationship with the thiol conversion, as shown in 2 Figure 18

[0252] Example 8: Application of high RI thiol-yne monomers in a two-stage photopolymer system

[0253] ​​The ability of photopolymer systems to achieve high index contrast between the matrix and the writing monomer after exposure (light exposure) is one of the key specifications for the development of new holographic materials. However, achieving such high index contrast is often challenging due to the limited availability of proper high-RI monomers with low viscosity. To this end, thiol-ene writing chemistry was recently designed and implemented for high-fidelity hologram recording via a linear polyurethane binder approach. In a similar fashion, these synthetic high-RI alkyne monomers were used to record holograms with relatively high Δn in thin films. From Figure 18 It was observed that when using 2d and commercially available trimethylolpropane tri(3-mercaptopropionate) (TMPTMP) as the writing monomer, a peak diffraction efficiency of 80% was achieved at high spatial frequencies. The angular replay spectrum of the recorded hologram showed good agreement with the coupled-wave theory fit. The dynamic range (Δn) and thickness of holograms using other alkyne writing monomers 2a and 2c are also summarized in Figures 19A-19B The hologram recorded with 2d exhibited the highest Δn of 0.018, presumably due to the higher refractive index of this writing monomer composition compared to 2a and 2c. However, the diffraction blur caused by incomplete conversion of these writing monomers reduced the overall index contrast, and there were still limitations to achieving high index modulation. It is noteworthy that the haze values of all these hologram measurements were found to be below 1.5%. The slightly higher haze observed for monomer 2d is attributed to the low miscibility of this rigid core monomer with the polyurethane (urethane) binder implemented here.

[0254] Another application of high-refractive index photocurable thiol-yne resins was demonstrated by recording two-dimensional micron-scale high-fidelity refractive index structures on a poly(urethane-thiourethane) stage 1 matrix. The model system shown here consisted of a poly(urethane-thiourethane) matrix incorporating the high-refractive index B2 resin. In the first stage, the poly(urethane-thiourethane) matrix was cured at ambient temperature and a 250 μιη thick film of this material was cast between two glass slides. In the second stage, the film was illuminated through a photomask to record a two-dimensional array of refractive index structures (100 μιη square) using a 405 nm LED source, as shown in the optical microscope image in Figure 20

[0255] Enumerated embodiments

[0256] The following exemplary embodiments are provided, the numbering of which is not to be interpreted as specifying an order of importance:

[0257] Embodiment 1 provides a composition comprising:

[0258] at least one polymer;

[0259] ​a polymeric binder comprising a plurality of allyl groups; and

[0260] at least one monomer of Formula (I):

[0261]

[0262] and at least one monomer of Formula (II):

[0263]

[0264] wherein:

[0265] each occurrence of X is independently H or optionally substituted C 6-14 aryl;

[0266] each Y is independently -S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, -CH(SH)-, -CH[O-CH2-CH=CH2]-, or -CH[O-CH2-CºCH]-;

[0267] each Y T is independently H, -SH, -CH=CH2, -CºCH, or optionally substituted C 6-14 aryl;

[0268] each Z is independently -S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, or -CH(SH)-;

[0269] each Z T is independently H, -SH, or -CH2SH;

[0270] m is an integer in the range of 0 to 100; and

[0271] n is an integer in the range of 0 to 100.

[0272] Embodiment 2 provides the composition of Embodiment 1, wherein the polymer is a linear polyurethane.

[0273] Embodiment 3 provides the composition of any one of Embodiments 1-2, wherein the polymeric binder comprises about 0 to 80 mol% allyl groups.

[0274] Embodiment 4 provides the composition of any one of Embodiments 1-3, wherein the polymer comprises polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone.

[0275] Embodiment 5 provides the composition of any one of Embodiments 1-4, wherein the ratio of monomers of Formula (I) to monomers of Formula (II) is about 9:1 to about 1:9.

[0276] Embodiment 6 provides the composition of any one of embodiments 1-5, wherein (Z) n -Z T comprises at least one -SH moiety.

[0277] Embodiment 7 provides the composition of any one of embodiments 1-6, wherein (Z) n -Z T comprises at least two -SH moieties.

[0278] Embodiment 8 provides the composition of any one of embodiments 1-7, wherein the monomer of formula (II) is selected from:

[0279]

[0280] Embodiment 9 provides the composition of any one of embodiments 1-8, wherein X is phenyl.

[0281] Embodiment 10 provides the composition of any one of embodiments 1-9, wherein (Y) m is linear.

[0282] Embodiment 11 provides the composition of any one of embodiments 1-10, wherein (Y) m comprises at least one of -CH(O-CH2-CH=CH2)- or -CH(O-CH2-C≡CH)-.

[0283] Embodiment 12 provides the composition of any one of embodiments 1-11, wherein (Y) m comprises at least two moieties independently selected from -CH(O-CH2-CH=CH2)- and -CH(O-CH2-C≡CH)-.

[0284] Embodiment 13 provides the composition of any one of embodiments 1-12, wherein the monomer of formula (I) is selected from:

[0285]

[0286] Embodiment 14 provides the composition of any one of embodiments 1-13, wherein the monomer of formula (I) and the monomer of formula (II) collectively comprise about 1 to 80% (w / w) of the composition.

[0287] Embodiment 15 provides the polymerized composition of any one of embodiments 1-14.

[0288] Embodiment 16 provides the polymerized composition of any one of embodiments 1-15, wherein the plurality of allyl groups crosslink with the monomers of formula (I) and formula (II).

[0289] Embodiment 17 provides a film comprising the composition of any one of embodiments 1-14.

[0290] Embodiment 18 provides a method of recording a hologram, the method comprising:

[0291] providing a composition of any one of embodiments 1-14; and

[0292] exposing the composition to laser irradiation to form a hologram.

[0293] Embodiment 19 provides the method of embodiment 18, wherein the providing step comprises covering an inert substrate with the film.

[0294] Embodiment 20 provides the method of any one of embodiments 18-19, wherein the exposing step comprises cross-linking the polymeric binder with the monomers of formula (I) and formula (II).

[0295] Embodiment 21 provides the method of any one of embodiments 18-20, wherein the hologram has a refractive index modulation (An) of about 0.01 to about 0.06.

[0296] Embodiment 22 provides a composition comprising:

[0297] at least one monomer of formula (I-A):

[0298]

[0299] and at least one monomer of formula (II):

[0300]

[0301] wherein:

[0302] each occurrence of X is independently H or optionally substituted C 6-14 aryl;

[0303] each occurrence of Y1and Y2is independently -S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, -CH(SH)-, -CH[O-CH2-CH=CH2]-, or -CH[O-CH2-CºCH]-;

[0304] each occurrence of Y T1 and Y T2 is independently H, -SH, -CH=CH2, -CºCH, or optionally substituted C 6-14 aryl;

[0305] each Z is independently S-, -CH2-, -CH2CH2-, -CH(CH3)CH2-, -CH2CH(CH3)-, or -CH(SH)-;

[0306] each Z T is independently H, -SH, or -CH2SH;

[0307] each m1 and m2 is independently an integer in the range of 0 to 100; and

[0308] n is an integer in the range of 0 to 100.

[0309] Embodiment 23 provides the polymeric composition of Embodiment 22.

[0310] Embodiment 24 provides the polymeric composition of Embodiment 23 having a refractive index of about 1.63 to about 1.69.

[0311] Embodiment 25 provides the composition of any one of Embodiments 22-24, wherein (Z) n -Z T comprises at least one -SH moiety.

[0312] Embodiment 26 provides the composition of any one of Embodiments 22-25, wherein (Z) n -Z T comprises at least two -SH moieties.

[0313] Embodiment 27 provides the composition of any one of Embodiments 22-26, wherein the monomer of Formula (II) is selected from:

[0314]

[0315] Embodiment 28 provides the composition of any one of Embodiments 22-27, wherein m1 is 1, Y1 is -S-, and YT1 is phenyl.

[0316] Embodiment 29 provides the composition of any one of Embodiments 22-28, wherein at least one of (Y1) m1 and (Y2) m2 is linear.

[0317] Embodiment 30 provides the composition of any one of Embodiments 28, wherein at least one of (Y1) m1 and (Y2) m2 comprises at least one of CH(O-CH2-CH=CH2)- or -CH(O-CH2-CºCH)-.

[0318] Embodiment 31 provides the composition of any one of Embodiments 30, wherein (Y1) m1and at least one of (Y2) m2 comprises at least two moieties independently selected from -CH(O-CH2-CH=CH2)- and -CH(O-CH2-CºCH)-.

[0319] Embodiment 32 provides the composition of any one of embodiments 22-31, wherein Y T1 and Y T2 is -CºCH.

[0320] Embodiment 33 provides the composition of any one of embodiments 22-32, wherein the monomer of formula (I-A) is selected from:

[0321]

Claims

1. A composition comprising: at least one polymer; a linear polyurethane polymeric binder comprising at least 10 mol% allyl side chains; and at least one monomer of Formula (I): and at least one monomer of Formula (II): wherein: X is an optionally substituted phenyl group; each Y is independently -S-, -CH2-, -CH[O-CH2-CH=CH2]-, or -CH[O-CH2-CºCH]-, wherein at least one Y is -CH[O-CH2-CH=CH2]- or -CH[O-CH2-CºCH]-; Y T is optionally substituted phenyl; each Z is independently -S-, -CH2-, or -CH(SH)-; Z T is -SH or -CH2SH; m is an integer in the range of 10 to 100; and n is an integer in the range of 6 to 100.

2. The composition of claim 1, wherein the linear polyurethane polymeric binder further comprises polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone.

3. The composition of claim 1, wherein the ratio of the monomer of Formula (I) to the monomer of Formula (II) is 9:1 to 1:

9.

4. The composition of claim 1, wherein the monomer of Formula (II) is selected from:

5. The composition of claim 1, wherein (Y) m is a straight chain.​ 6. The composition of claim 1, wherein (Y) m comprises at least two moieties independently selected from -CH(O-CH2-CH=CH2)- and -CH(O-CH2-CºCH)-.

7. The composition of claim 1, wherein the monomer of Formula (I) is selected from:

8. The composition of claim 1, wherein the monomers of Formula (I) and Formula (II) collectively comprise 1 to 80% w / w of the composition.

9. A polymerized composition of claim 1.

10. The polymerized composition of claim 9, wherein the allyl side chains of the linear polyurethane polymeric binder are crosslinked with the monomer of Formula (I) and the monomer of Formula (II).

11. A film comprising the composition of claim 1.

12. A method of recording a hologram, the method comprising: providing a film of claim 11; and exposing the composition to laser irradiation to form a hologram.

13. The method of claim 12, wherein the providing step comprises covering an inert substrate with the film.

14. The method of claim 12, wherein the exposing step comprises crosslinking the polymeric binder with the monomer of Formula (I) and the monomer of Formula (II).

15. The method of claim 12, wherein the hologram has an exponential modulation Δn of 0.01 to 0.

06.

16. A composition comprising: at least one polymer; a linear polyurethane polymeric binder comprising at least 10 mol% allyl side chains; and at least one monomer of Formula (I) selected from: and at least one monomer of Formula (II): wherein: each Z is independently -S-, -CH2-, or -CH(SH)-; Z T is -SH or -CH2SH; and n is an integer in the range of 6 to 100.

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