(Methyl) acrylate monomer, holographic recording medium, preparation method and related device

Abstract

The invention discloses a (methyl) acrylate monomer, a holographic recording medium, a preparation method and a related device.The structural formula of the (methyl) acrylate monomer is as shown in G1-G5. The preparation method is easy to operate and high in synthesis yield, and further, the holographic recording medium can be applied to holographic recording. The (methyl) acrylate monomer with the structure is introduced into the photopolymer type holographic recording medium, reverse migration of a short polymer chain can be effectively inhibited, and therefore the holographic recording medium with high sensitivity and high diffraction efficiency is obtained, and the invention further provides a preparation method of the holographic recording medium. The invention also provides a volume holographic grating, a holographic optical element and an optical device comprising the holographic recording medium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of holographic material, in particular to a (meth)acrylate monomer, a holographic recording medium, a preparation method and a related device. BACKGROUND

[0002] The performance of photopolymer is usually improved by using a low refractive film-forming resin and a high refractive writing monomer (the refractive index of the writing monomer is usually less than 1.6), so that the refractive index difference between the two is small (Δn≈0.1-0.2), which limits the performance optimization. In addition, during holographic exposure, short-chain polymers are prone to migrate from the coherent bright area to the coherent dark area, reducing the diffraction efficiency of the grating.

[0003] Although the addition of a multifunctional monomer to the writing monomer can effectively inhibit the reverse migration of the polymer chain, the refractive index of the multifunctional monomer is usually low (about 1.55), and the diffraction efficiency of the photopolymer formed thereby is low, which is not conducive to the further preparation of holographic gratings with high diffraction efficiency. SUMMARY

[0004] Embodiments of the present application aim to provide a (meth)acrylate monomer with multifunctionality and high refractive index, which can effectively inhibit the reverse migration of short-chain polymers to the coherent dark area.

[0005] In a first aspect, the present application provides a (meth)acrylate monomer, the structural formula of which is shown in any one of G1-G5:

[0006] In the formula, R1 represents methyl or hydrogen.

[0007] As can be seen from the above technical solution, the (meth)acrylate monomer provided in the first aspect of the present application has multifunctionality, i.e., it contains multiple carbon-carbon double bond (C=C) free radicals that can participate in radical polymerization simultaneously, forming a highly cross-linked network structure. In addition, due to the introduction of multiple benzene rings and sulfur atoms, the monomer exhibits a high refractive index, with a refractive index greater than 1.65 and less than 1.75.

[0008] In a second aspect, the present application provides a preparation method of the (meth)acrylate monomer described above, the preparation method comprising:

[0009] In step S101, under an inert environment, compound M1, a target compound, and compound M2 are dissolved in a first solvent to obtain a first mixture, and the first mixture is subjected to a first treatment operation. The first mixture after the first treatment operation is separated to obtain compound P1.

[0010] The first processing operation comprises at least a heating operation and a stirring operation, the target compound comprises a first catalyst, a ligand and a base reagent, and the compound M1 is selected from the compounds with the following structural formula:

[0011]

[0012] The compound M2 is selected from the compounds with the following structural formula:

[0013]

[0014] The compound P1 has any one of the following structural formula:

[0015]

[0016] In step S102, the compound P1 is dissolved in a second solvent with an acid-binding agent, and a compound M3 is added for reaction to obtain a second mixture after reaction, and the second mixture is separated to obtain the (meth)acrylate monomer.

[0017] The compound M3 is acryloyl chloride or methacryloyl chloride.

[0018] As can be seen from the above technical solution, the preparation method of the (meth)acrylate monomer provided in the second aspect of the present application can obtain a (meth)acrylate monomer with high yield through only two-step reaction, and the synthesis condition is simple and easy to operate, and is convenient for large-scale production.

[0019] In a third aspect, the present application provides a photopolymer type holographic recording medium, raw materials of which comprise the following components a) to h):

[0020] The component a) is a compound with multiple isocyanate reactive functional groups.

[0021] The component b) is a polyisocyanate-based compound.

[0022] The component c) is a (meth)acrylate monomer.

[0023] The component d) is a polymerizable monomer.

[0024] The component e) is a photosensitive initiation system.

[0025] The component f) is a chain transfer agent.

[0026] The component g) is an optional second catalyst.

[0027] The component h) is an optional additive.

[0028] The (meth)acrylate monomer is at least one of the aforementioned (meth)acrylate monomers G1-G5.

[0029] From the above technical solutions, the third aspect of the present application provides a photopolymer type holographic recording medium containing the above (meth) acrylate monomer. By introducing a multifunctional high refractive index (meth) acrylate monomer into the photopolymer type holographic recording medium, the refractive index difference between the recording monomer and the film-forming resin can be improved, and the reverse migration of the shorter polymer chain can be effectively inhibited, thereby obtaining a high-sensitivity holographic recording medium.

[0030] In the fourth aspect, the present application provides a preparation method of the above photopolymer type holographic recording medium, comprising:

[0031] The compound having multiple isocyanate reactive functional groups, the polyisocyanate-based compound, the (meth) acrylate monomer, the polymerizable monomer, the photosensitive initiation system, the chain transfer agent, the second catalyst and the additive are weighed in a container, and are fully stirred and dissolved to form a mixture solution;

[0032] The mixture solution is filtered using a filter membrane to obtain a second solution;

[0033] The second solution is coated on a substrate, and after drying, the photopolymer type holographic recording medium is obtained.

[0034] From the above technical solutions, the preparation method of the photopolymer type holographic recording medium provided by the present application is simple and low in cost, can ensure uniform dispersion of each component, improve the light transmittance and refractive index modulation of the holographic recording medium, thereby enhancing the resolution and diffraction efficiency of the hologram. In addition, the filtering step can effectively remove impurities, reduce light scattering, and improve the storage stability and imaging quality of the holographic medium.

[0035] In the fifth aspect, the present application provides a volume holographic recording grating, wherein the photopolymer type holographic recording medium used by the volume holographic recording grating comprises the photopolymer type holographic recording medium as described above.

[0036] From the above technical solutions, the volume holographic recording grating provided by the present application has high diffraction efficiency, high sensitivity and high refractive index modulation of holographic performance.

[0037] In the sixth aspect, the present application provides a holographic optical element, wherein the raw material of the holographic optical element comprises the photopolymer type holographic recording medium as described above.

[0038] From the above technical solutions, the holographic optical element provided by the present application has high diffraction efficiency, high sensitivity and high refractive index modulation of optical performance.

[0039] Seventhly, this application provides an optical device including the holographic optical element as described above. As can be seen from the above technical solutions, the optical device proposed in this application has excellent optical performance, clear images, and the ability to store a large amount of data. Attached Figure Description

[0040] Figure 1 This document shows holographic exposure characteristic curves of photopolymer-type holographic recording media 6-1 to 6-5 in Embodiment 6 of this application;

[0041] Figure 2 The diagram shows the holographic exposure characteristics of the photopolymer-type holographic recording medium in the comparative example of this application. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0044] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0045] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0046] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0047] It should be understood that photopolymer-based holographic recording media materials used for holographic recording utilize light to polymerize writing monomers, which then form a refractive index-modulated phase-type holographic grating with the film-forming resin to achieve holographic recording. In the coherent bright region, monomer polymerization is consumed, resulting in a decrease in concentration, while in the coherent dark region, monomers hardly react. The difference in monomer concentration between the bright and dark regions causes monomers in the dark region to begin migrating towards the bright region. Simultaneously, the film-forming resin in the bright region is squeezed into the dark region. Ultimately, the refractive index of the bright region approaches the refractive index of the polymer, and the refractive index of the dark region approaches the refractive index of the film-forming resin, thus forming a refractive index-modulated phase-type volume holographic grating.

[0048] It should be noted that photopolymer-based holographic recording media with superior performance typically require the film-forming resin to have a lower refractive index and the writing monomer to have a higher refractive index.

[0049] However, the refractive index of the writing monomers currently available for photopolymers is typically below 1.6, resulting in a small refractive index difference between the recording monomer and the film-forming resin (usually 0.1–0.2). Furthermore, during holographic exposure, shorter polymer chains tend to migrate backward from the coherent bright region to the coherent dark region, leading to a decrease in the refractive index modulation (Δn) of the recording grating and thus reducing its diffraction efficiency. Even though adding multifunctional monomers can effectively suppress the backward migration of polymer chains, the refractive index of existing multifunctional monomers is typically low (around 1.55), which is detrimental to photopolymer recording of holographic gratings with high diffraction efficiency.

[0050] Based on this, this application provides a (meth)acrylate monomer as a component of a writing monomer, the structural formula of which is shown in any one of G1-G5:

[0051] in,

[0052] R1 represents methyl or hydrogen.

[0053] In this embodiment, the (meth)acrylate monomers are multifunctional, meaning they contain multiple carbon-carbon double bonds (C=C) that can simultaneously participate in free radical polymerization to form a highly cross-linked network structure. Furthermore, due to the introduction of multiple benzene rings and sulfur atoms, the monomers exhibit a high refractive index, which is greater than 1.65 and less than 1.75. This effectively matches common photosensitive resin systems, reduces light scattering loss during holographic recording, and improves diffraction efficiency. At the same time, the high refractive index helps to enhance the optical anisotropy of the material, optimizing the resolution and storage capacity of the hologram.

[0054] This application also provides a method for preparing the above-mentioned (meth)acrylate monomers, including:

[0055] Step S101: Under an inert environment, compound M1, target compound, and compound M2 are dissolved in a first solvent to obtain a first mixture, and the first mixture is subjected to a first treatment operation. The first mixture after the first treatment operation is separated to obtain compound P1.

[0056] The first processing operation includes at least heating and stirring operations. The target compound includes a first catalyst, a ligand, and a base reagent. Compound M1 is selected from compounds with the following structural formulas:

[0057]

[0058] Compound M2 is selected from compounds with the following structural formulas:

[0059]

[0060] The structural formula of compound P1 is shown in any of the following examples:

[0061]

[0062] It is understood that in step S101, under an inert environment, compound M1 and compound M2 undergo a Suzuki coupling reaction to generate compound P1 under the action of the target compound (i.e., the first catalyst, ligand, and base reagent). The first processing operation includes at least a heating operation and a stirring operation, wherein the heating operation and the stirring operation can be performed simultaneously or staggered. For example, stirring and heating can be performed simultaneously, or the stirring operation can be performed for a period of time first and then the heating operation can be performed. This application does not impose any limitations.

[0063] It can also be understood that the first mixture includes at least compound M1, the target compound (i.e., the first catalyst, ligand and base reagent), and compound M2, and the first mixture after the first treatment operation should also include compound P1.

[0064] In some embodiments, step S101 is carried out at 60-120°C for 2-24 hours, resulting in better reaction performance. It is understood that excessively high reaction temperatures may trigger boron deboration of boric acid or catalyst decomposition, while excessively low temperatures will lead to a significant decrease in the reaction rate, and the occurrence of side reactions such as self-coupling or hydrolysis of boric acid will also lead to a decrease in reaction selectivity.

[0065] It needs to be further understood that, in order to prevent catalyst deactivation and the introduction of more impurities due to increased side reactions, coupling reactions are usually carried out under the protection of an inert gas environment, including but not limited to nitrogen and argon.

[0066] In some specific examples, in step S101, the molar ratio of bromine groups in compound M1 to that in compound M2 is 1:(1 to 1.2), based on the number of bromine groups in compound M1.

[0067] Typically, but not limitingly, the molar ratio of bromine groups in compound M1 to those in compound M2, based on the number of bromine groups in M1, can be, for example, 1:1, 1:1.1, or 1:1.2.

[0068] For example, when the structural formula of compound M1 is When compound M1 contains three bromine groups, the molar ratio of compound M1 to compound M2 is 1:3. When the structural formula of compound M1 is... Since compound M1 contains two bromine groups, the molar ratio of compound M1 to compound M2 is 1:2.

[0069] In some embodiments, the molar ratio of compound M1 to the base reagent is 1:(1 to 3), typically but not limitingly, for example, the molar ratio of compound M1 to the base reagent is 1:1, 1:2, 1:3.

[0070] Alkaline reagents include, but are not limited to, one or more of the following: potassium carbonate (K2CO3), sodium carbonate (Na2CO3), cesium carbonate (Cs2CO3), potassium phosphate (K3PO4), potassium fluoride (KF), cesium fluoride (CsF), tetrabutylammonium fluoride (TBAF), barium hydroxide (Ba(OH)2), sodium hydroxide (NaOH), and potassium trimethylsilanolate (TMSOK).

[0071] It should be understood that in the Suzuki coupling reaction, the alkaline reagent plays a triple role in activating boric acid (i.e., compound M2), neutralizing acidic byproducts, and stabilizing the catalyst, ensuring the efficient conduct of Suzuki coupling. The dosage and ratio of alkaline reagent are of great significance.

[0072] In addition, the first solvent includes, but is not limited to, one or more of toluene, dimethoxyethane, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, and 1,4-dioxane, or it may be a mixed solvent of water and an organic solvent, such as water and toluene, water and ethanol, water and acetonitrile, or water and dioxane.

[0073] It is understandable that the first solvent should ensure the dissolution of the reaction substrates (i.e., compounds M1 and M2) to allow them to fully dissolve in the reaction system, forming a homogeneous reaction system. This promotes effective contact between the catalyst and the reaction substrate, improving reaction efficiency and product yield. An appropriate amount of water can promote the dissolution of the inorganic base in the reaction system, further accelerating the Suzuki coupling reaction rate. For example, a mixed solvent of water and 1,4-dioxane (mixed in a 1:4 or 1:5 ratio) can be used.

[0074] It should be noted that the solvents mentioned above are merely illustrative examples, and the solvents that can be used in this application are not limited to these.

[0075] In some embodiments, the first catalyst includes, but is not limited to, one or more of the following: Pd(PPh3)4 (tetra(triphenylphosphine)palladium), PdCl2(dppf) (bis(diphenylphosphine-ferrocene)palladium dichloride), Pd(OAc)2 (palladium acetate), Pd2(dba)3 (tris(dibenzylacetone)palladium), PdCl2(PPh3)2 (bis(triphenylphosphine)palladium dichloride), Pd(dtbpf)Cl2 (palladium chloride containing di-tert-butylphosphine-ferrocene ligands), Pd(PPh3)2Cl2 (bis(triphenylphosphine)palladium dichloride), NiCl2(dppf) (bis(diphenylphosphine-ferrocene)nickel chloride), Pd / C (palladium on carbon), Bedford palladium catalyst, BI-DIME / AntPhos and other DHBOP monodentate phosphine ligand catalysts, Pd(tBu)3-G4 (palladium catalyst containing tert-butyl ligands), and Buchwald precatalyst.

[0076] Typically, the amount of the first catalyst is 0.5 to 5% (i.e., 0.5-5 mol%) of the molar number of the reaction substrate. In step S101, the amount of the first catalyst being 0.5 to 5% (i.e., 0.5-5 mol%) of the molar number of compound M1 has a better catalytic effect. Typically, but not limitingly, the amount of the first catalyst can be, for example, 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, 3.5 mol%, 4 mol%, or 5 mol% of compound M1.

[0077] In some embodiments, the addition of ligands can pre-activate the catalyst, resulting in better reaction performance. Ligands include, but are not limited to, one or more of triphenylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, 1,3-bis(2,4,6-trimethylphenyl)imidazolium-2-ylidene, tricyclohexylphosphine, 1,1'-bis(diphenylphosphino)ferrocene, XPhos, and monodentate phosphine ligands. Typically, the amount of ligand used is 1-10% (i.e., 1-10 mol%) of the molar number of the reaction substrate. In other words, in step S101, the amount of ligand used is 1-10% (i.e., 1-10 mol%) of the molar number of compound M1.

[0078] Step S102: Dissolve compound P1 and the acid-binding agent in a second solvent, and add compound M3 to react to obtain a second mixture after the reaction. Separate the second mixture to obtain (meth)acrylate monomers, wherein compound M3 is acryloyl chloride or methacryloyl chloride.

[0079] In this embodiment, the desired (meth)acrylate monomers can be synthesized through a two-step reaction, with a monomer yield of over 95%. The synthesis conditions are simple and easy to operate, facilitating large-scale production.

[0080] It is understood that in step S102, compound P1 is activated by the acid-binding agent to generate a more reactive alkoxy group, thereby enhancing nucleophilicity and further promoting the substitution reaction between compound P1 and compound M3 to obtain (meth)acrylate monomers. In specific examples, the reaction is usually carried out at 0°C (i.e., in an ice bath). Compound M3 is added dropwise to the mixed solution of compound P1 and triethylamine at 0°C to avoid local overheating or excessive concentration that could trigger side reactions. A reaction time of 0.5 h to 3 h typically yields optimal reaction results.

[0081] It can also be understood that the second mixture includes at least one of compound P1, acid-binding agent, compound M3, and the corresponding (meth)acrylate monomers G1-G5.

[0082] It should be further understood that, because compound M3 (i.e., acryloyl chloride or methacryloyl chloride) is a highly reactive acylating agent, it is prone to side reactions, leading to a reduction in the amount actually participating in the target reaction. Therefore, it is usually necessary to use an excess to compensate for the consumption by side reactions and ensure that sufficient acryloyl chloride reacts with the substrate. In addition, since the acid-binding agent needs to provide basic conditions to promote the deprotonation of compound P1 and neutralize the hydrochloric acid generated in the reaction to prevent the decomposition of the substrate or product, the acid-binding agent is usually also used in excess. Specifically, in some examples, the molar ratio of compound P1, compound M3, and acid-binding agent is 1:(1-3):(1-4) based on the number of hydroxyl groups in compound P1.

[0083] Typically, but not limitingly, the molar ratio of compound P1, compound M3, and acid-binding agent, based on the number of hydroxyl groups in compound P1, can be, for example, 1:3:4, 1:3:3, 1:2:3, 1:2.5:3.5, 1:2:4, etc.

[0084] For example, compound P1 contains two hydroxyl groups. When the amount of compound P1 is 1 mol, the amount of compound M3 can be 2-6 mol, and the amount of acid-binding agent can be 2-8 mol.

[0085] For example, compound P3 and triethylamine were dissolved in an organic solvent in an ice bath and stirred for 10 min. Then, acryloyl chloride or methacryloyl chloride was added dropwise to the mixed solution of compound P3 and triethylamine at 0 °C. After the reaction was completed, dilute hydrochloric acid was added dropwise to remove excess acryloyl chloride or methacryloyl chloride. The mixture was then washed successively with saturated NaCl solution, saturated NaHCO3 solution, and deionized water. The organic phase was dried over anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. The (meth)acrylate monomers were then separated by column chromatography.

[0086] The second solvent includes, but is not limited to, one or more of ethanol, petroleum ether, dichloromethane, chloroform, ethyl acetate, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide.

[0087] The acid-binding agents include, but are not limited to, one or more of the following: triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, tetrabutylammonium bromide, potassium carbonate, ammonium carbonate, and sodium carbonate.

[0088] This application also provides a photopolymer-type holographic recording medium, including a writing monomer, which includes (meth)acrylate monomers and polymerizable monomers.

[0089] Furthermore, in some embodiments, the raw material of the photopolymer-type holographic recording medium comprises the following components a)-h):

[0090] Component a) A compound having multiple isocyanate reactive functional groups.

[0091] Component b) Polyisocyanate group compounds,

[0092] Component c) at least one of the aforementioned (meth)acrylate monomers G1-G5,

[0093] Component d) can polymerize monomers.

[0094] Component e) Photosensitive initiation system,

[0095] Component f) Chain transfer agent,

[0096] Component g) optionally a second catalyst,

[0097] Component h) can be optionally added.

[0098] Among them, compounds with multiple isocyanate reactive functional groups and polyisocyanate group compounds form film-forming resins.

[0099] In this embodiment, multifunctional, high-refractive-index (meth)acrylate monomers are used as components of the writing monomer. This not only effectively suppresses the reverse migration of shorter polymer chains, but also allows for a greater refractive index difference between the writing monomer and the film-forming resin, forming a photopolymer-type holographic recording material with excellent properties such as high sensitivity and high diffraction efficiency. Specifically, in some examples, the photopolymer-type holographic recording medium has a photosensitivity greater than 100 cm / mJ, a recording grating diffraction efficiency greater than 95%, and an exposure dose less than 20 mJ / cm. 2 .

[0100] More specifically, in some examples, the composition and content of the photopolymer-type holographic recording medium are as follows:

[0101] Component a) 10–50 wt% of compounds having multiple isocyanate reactive functional groups.

[0102] Component b) Polyisocyanate group compound 10-50 wt%,

[0103] Component c) (meth)acrylate monomers 1-30 wt%,

[0104] Component d) can polymerize 10–40 wt% of monomers.

[0105] Component e) Photoinitiator system 0.1–3 wt%,

[0106] Component f) Chain transfer agent 0.1–3 wt%,

[0107] Component g) Second catalyst 0.1-5 wt%,

[0108] Component h) Additives 0.1-10 wt%.

[0109] In this embodiment, by rationally controlling the composition ratio of the photopolymer holographic recording medium, the various components can work together fully, and the holographic performance of the final photopolymer holographic recording medium will not deteriorate due to an excess or deficiency of a certain component. This ensures that the final photopolymer holographic recording medium has better overall holographic performance, thereby achieving high resolution, high diffraction efficiency and long-term stability.

[0110] In some embodiments, the (meth)acrylate monomer accounts for 0.1 to 30 wt% of the total content of the photopolymer holographic recording medium.

[0111] Typically, but not limitingly, the content of (meth)acrylate monomers in the entire photopolymer holographic recording medium can be 0.1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, or any range of two values.

[0112] In this embodiment, the content of (meth)acrylate monomers ranges from 0.1 to 30 wt% to ensure that sufficient active monomers are provided to participate in photopolymerization so that the resulting writing monomers have a sufficient concentration to achieve the concentration difference between the bright and dark areas after the reaction under light.

[0113] In some embodiments, the isocyanate reactive functional group is a hydroxyl group. Compounds having multiple isocyanate reactive functional groups include compounds with a refractive index less than or equal to a first refractive index threshold and having two or more hydroxyl functional groups, wherein the first refractive index threshold is any value between 1.5 and 1.55. Optionally, polyisocyanate-based compounds include compounds with a refractive index less than or equal to a second refractive index threshold and having two or more isocyanate groups, wherein the second refractive index threshold is any value between 1.5 and 1.55.

[0114] Typically, but not restrictively, the first refractive index threshold can be 1.5, 1.51, 1.52, 1.53, 1.54, 1.55, or any value between any two values, and the second refractive index threshold can be 1.5, 1.51, 1.52, 1.53, 1.54, 1.55, or any value between any two values.

[0115] In this embodiment, a compound with multiple isocyanate reactive functional groups having a refractive index less than or equal to 1.5 to 1.55 forms a low refractive index film-forming resin with a polyisocyanate group compound having a refractive index less than or equal to 1.5 to 1.55. The low refractive index film-forming resin forms a significant refractive index difference (Δn≥0.1) with the high refractive index recording monomer (i.e., the refractive index of the above-mentioned (meth)acrylate monomer is 1.65 to 1.75), which can enhance the diffraction efficiency of the holographic grating, while avoiding the increase in background noise caused by the high refractive index of the substrate itself.

[0116] In some embodiments, the isocyanate reactive functional group is a hydroxyl group, and the molar ratio of hydroxyl group to isocyanate functional group is 1:1. That is, in the film-forming resin that forms a photopolymer type holographic recording medium, the molar ratio of hydroxyl group in the compound having multiple isocyanate reactive functional groups to isocyanate functional group in the polyisocyanate group compound is 1:1.

[0117] Furthermore, in some examples, the compound having multiple isocyanate reactive functional groups may be one or more of tetraethylene glycol, trimethylolethane, glycerol, triethanolamine, polyester polyols with a molecular weight of 200 to 2000, polycarbonate polyols, and polyether polyols, but is not limited thereto.

[0118] Polyisocyanate compounds include, but are not limited to, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tri(hexamethylene)isocyanate, butane-1,4-diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate.

[0119] In some examples, the polymerizable monomer is selected from at least one of alkenylnaphthalene compounds, alkenylanthracene compounds, alkenylbenzene compounds, acrylic compounds, methacrylic acid compounds, acrylate compounds, methacrylate compounds, N-vinylpyrrole, N-vinylcarbazole, N-vinylimidazol, N-vinylindole, N-vinylpyrrolidone, and trans-N-3-yntynebutenylcarbazole.

[0120] In specific examples, alkenylbenzene compounds include, but are not limited to, styrene, 2-chlorostyrene, 2-bromostyrene, 3-chlorostyrene, 3-bromostyrene, 4-chlorostyrene, 4-bromostyrene, p-(chloromethyl)styrene, and p-(bromomethyl)styrene.

[0121] For example, methacrylic acid compounds can be methacrylic acid and its derivatives. For instance, methacrylate compounds can be selected from 2-phenoxyethyl methacrylate, benzyl methacrylate, p-bromophenyl methacrylate, p-chlorophenyl methacrylate, 2,4,6-trichlorophenyl methacrylate, pentabromophenyl methacrylate, pentachlorophenyl methacrylate, phenoxyethyl methacrylate, phenoxyethoxyethyl methacrylate, 1,4-di(2-thionaphthyl)2-butyl methacrylate, pentabromobenzyl methacrylate, 2-naphthyl methacrylate, bisphenol A dimethacrylate, tetrabromobisphenol A dimethacrylate, etc.

[0122] In specific examples, acrylate compounds include, but are not limited to, pentabromophenyl acrylate, pentachlorophenyl acrylate, phenoxyethyl acrylate, pentabromobenzyl acrylate, 2-naphthyl acrylate, 1,4-di(2-thionaphthyl)2-butyl acrylate, phenoxyethoxyethyl acrylate, bisphenol A diacrylate, tetrabromobisphenol A diacrylate, 2-phenoxyethyl acrylate, benzyl acrylate, p-chlorophenyl acrylate, 2,4,6-trichlorophenyl acrylate, p-bromophenyl acrylate, 2,4,6-tribromophenyl acrylate, propane-2,2-diylbis[(2,6-dibromo-4,1-phenylene)oxy(2-{[3,3,3-tris(4-chlorophenyl)propionyl]oxy}propane-3,1-diyl)oxyethane-2,1-diyl]diacrylate.

[0123] In specific examples, vinylanthracene compounds may be selected from 2-vinylanthracene, 9-vinylanthracene, etc.

[0124] In specific examples, vinylnaphthalene compounds can be selected from 1-vinylnaphthalene, 2-vinylnaphthalene, etc.

[0125] In some implementations, the photoinitiation system is composed of a photosensitizer and a photoinitiator, which work synergistically to construct a broadband visible light initiation system. The photosensitizer selectively absorbs laser energy at specific wavelengths (e.g., 532 nm or 633 nm) and activates the photoinitiator through an energy transfer mechanism, thereby significantly expanding the system's photosensitive wavelength range. Therefore, different broadband responses can be achieved by controlling the type of photosensitizer. Under irradiation with light within a specific wavelength range, the photosensitizer in the photoinitiation system is activated accordingly, absorbs light energy, and transfers the light energy to the photoinitiator. This allows the photoinitiator to be activated under light radiation of more frequencies. The activated photoinitiator efficiently generates active free radicals, rapidly initiating monomer polymerization reactions, thus enabling the construction of a holographic grating structure. This improves the photosensitivity of the photopolymer-based holographic recording medium and enhances compatibility with lasers of different wavelengths, providing a more flexible light source selection scheme for holographic storage.

[0126] It is understandable that when a photoinitiator with a suitable wavelength is selected in the raw materials of a photopolymer holographic recording medium, a photosensitizer may not be added. For example, when the photoinitiator is diacetic titanium (Irgacure 784), a photosensitizer may not be added. This highly reactive orange solid photoinitiator can initiate the polymerization reaction of unsaturated resins under visible or ultraviolet light.

[0127] In some examples, the mass ratio of photosensitizer to photoinitiator is (0.001 to 1):(0.1 to 3). Typically, but not limitingly, the mass ratio of photosensitizer to photoinitiator can be 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, or 1:3, etc.

[0128] By adjusting the ratio of photosensitizer and photoinitiator within the above range, the energy transfer efficiency of the photosensitizer and the free radical yield of the photoinitiator can be balanced, avoiding energy waste caused by excessive photosensitizer or side reactions caused by excessive initiator. This allows for efficient initiation of the polymerization reaction while controlling the reaction rate within a reasonable range, thus controlling the grating formation speed within a certain range and ensuring the light transmittance of the photopolymer holographic recording medium, thereby achieving excellent diffraction efficiency.

[0129] Among them, photosensitizers are dyes that have high electron transfer efficiency under light irradiation, including but not limited to cyanine dyes, fluorescein dyes, coumarin ketone dyes, nitrogen-containing aromatic heterocyclic compounds, aromatic amine compounds, and benzylidene cycloalkanes ketone compounds.

[0130] For example, the photosensitizer may be one or more of the following: neomethylene blue, thionine, basic yellow, pinacyanin chloride, rhodamine 6G, gallium cyanide, ethyl violet, Victoria blue R, azurite blue, methylene blue, Astrazon Orange G, Darrow red, pyrrole red Y, basic red 29, quinaldinium red, crystal violet, brilliant green, pyrimethium I, azurite A, crystal violet cyanocyanate, malachite green cyanocyanate, etc.

[0131] Photoinitiators are initiators that can be activated by photochemical radiation and initiate polymerization reactions of corresponding polymerizable groups, including but not limited to aromatic ketones, benzoin and its derivatives, benzoyl ketals, acylphosphine oxides, ammonium arylboronate, chromium salts, aryl diazonium salts, onium salts, and organometallic compounds.

[0132] Specifically, the photoinitiator can be one or more of the following: benzophenone, alkylbenzophenone, 4,4'-bis(dimethylamino)benzophenone, anthrone and halogenated benzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, diacylphosphine oxide, phenyl dihydroxyacetate, camphorquinone, α-aminoalkylphenyl ketone, α,α-dialkoxyacetophenone, α-hydroxyalkylphenyl ketone, tetrabutylammonium triphenylhexylborate, tetrabutylammonium tri-(3-fluorophenyl)hexylborate, tetrabutylammonium tri-(3-chloro-4-methylphenyl)hexylborate, ferrocene compounds, iodonium salts, thiodonium salts, and hexaaryldiimidazole.

[0133] As a chain transfer agent, the chain transfer agent can control the polymer chain length within a certain reasonable range and effectively prevent excessive polymerization, ensuring that the final holographic recording medium has the required optical properties and diffraction efficiency.

[0134] In some embodiments, the chain transfer agent may be a thiol compound, such as one or more of dodecyl mercaptoethanol, mercaptoethanol, hexamethylene mercaptoethanol, phenylethyl mercaptoethanol, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 4-methyl-4H-1,2,4-triazole-3-thiol, but not limited thereto.

[0135] It is understandable that the molecular weight of (meth)acrylate monomers after polymerization with polymerizable monomers can be controlled by the photoinitiator system, the amount of chain transfer agent used, and the reaction conditions, and the amount used can be appropriately adjusted according to their types.

[0136] As a second catalyst, the second catalyst can effectively increase the reaction rate of related components and increase the consumption rate of related components after exposure, thereby quickly forming a concentration difference of monomers in the bright and dark areas and realizing a phase-type volume holographic grating with refractive index modulation.

[0137] In some embodiments, the second catalyst can be a tertiary amine catalyst or an organometallic catalyst, such as triethylenediamine, bis(dimethylaminoethyl) ether, dimethylethanolamine, 2-(2-dimethylaminoethoxy)ethanol, trimethylhydroxyethylpropanediamine, N,N-bis(dimethylaminopropyl)isopropanolamine, dibutyltin dilaurate, stannous octoate, potassium carboxylate catalysts, and bismuth carboxylate catalysts, but not limited thereto.

[0138] For example, additives can be selected from at least one of defoamers, leveling agents, plasticizers, and dehydrating agents. For instance, as defoamers, defoamers include silicone defoamers and silicone-free polymeric defoamers. Defoamers are mainly used to eliminate or suppress bubbles generated during material preparation and photocuring to ensure high resolution, high diffraction efficiency, and structural uniformity of the hologram.

[0139] Specifically, the defoamer can be selected from BYK-011, BYK-012, BYK-014, BYK-023, BYK-051N, BYK-085, BYK-1610, BYK-1707, BYK-1740, and BYK-1760 manufactured by BYK Corporation, DC65 and AFE-7820 manufactured by Dow Corning, or any mixture of these defoamers in any proportion, but is not limited thereto. Among them, the BYK series defoamers have excellent defoaming performance, good compatibility with other components, and good dispersibility. BYK-011, BYK-012, BYK-014, and BYK-051N are silicone-free polymeric defoamers. DC65 is a water-based ink that dries quickly, provides good printing results, and is not easily peeled off. AFE-7820 has highly efficient defoaming performance. The defoamer content in the photopolymer holographic recording medium is less than or equal to 3 wt%. Typically, but not limitingly, the defoamer content in the photopolymer holographic recording medium can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, etc.

[0140] In a specific example, the leveling agent is an organosilicon surface additive, and the leveling agent accounts for less than or equal to 3 wt% of the photopolymer holographic recording medium. Typically, but not limitingly, the leveling agent content in the photopolymer holographic recording medium can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, etc.

[0141] The leveling agent may be selected from BYK series leveling agents with excellent leveling properties manufactured by BYK Corporation, such as BYK-302, BYK-306, BYK-307, BYK-327, BYK-329, BYK-333, BYK-356, BYK-358, BYK-378, BYK-3455, BYK-3566, or any proportion of these surface additives, but is not limited thereto.

[0142] As a plasticizer, the plasticizer increases the plasticity of the polymer by intercalating between polymer molecular chains, weakening intermolecular stress, increasing molecular chain mobility, and reducing crystallinity. In specific examples, the plasticizer may be selected from one or more of toluene, xylene, dimethylformamide, dimethylacetamide, glycerol, and phthalates, but is not limited to these. The plasticizer content in the photopolymer holographic recording medium is less than or equal to 3 wt%. Typically, but not limitingly, the plasticizer content in the photopolymer holographic recording medium may be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, etc.

[0143] It is understandable that residual moisture in photopolymer-based holographic recording media may cause hydrolysis and failure of the photoinitiator system (such as the photoinitiator), reducing photosensitivity. Simultaneously, moisture can react with isocyanate groups (-NCO) involved in film-forming resin, generating urea bonds and releasing CO2, leading to bubbles or microstructural defects. Therefore, adding a dehydrating agent to maintain system dryness ensures the efficiency of the photopolymerization reaction, thereby improving the uniformity of the holographic grating and the storage life of the medium.

[0144] As dehydrating agents, dehydrating agents include, but are not limited to, p-toluenesulfonyl isocyanate, triethyl orthoformate, CUWR-WB20 dehydrating agent from Guangzhou Yourun Synthetic Materials Co., Ltd., ALT-201 dehydrating agent from Anxiang Elite Chemical Co., Ltd., and PCCI dehydrating agent from Shanghai Luer Chemical Trading Co., Ltd.

[0145] In some embodiments, the content of the dehydrating agent in the photopolymer holographic recording medium is less than or equal to 3 wt%. Typically, but not limitingly, the content of the dehydrating agent in the photopolymer holographic recording medium can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, etc.

[0146] This application also provides a method for preparing a photopolymer-based holographic recording medium, the method comprising:

[0147] Step S201: Weigh components a), b), c), d), e), f), g), and h) into a container and stir thoroughly until dissolved to form a mixture solution.

[0148] Step S202: Filter the mixture solution using a filter membrane to obtain a second solution, coat the second solution onto a substrate, and dry it to obtain the photopolymer holographic recording medium.

[0149] For example, drying is carried out in a dark room with a humidity of 10% to 85% and a temperature of 20°C to 50°C.

[0150] Furthermore, this application provides a volume holographic recording grating, wherein the photopolymer holographic recording medium used in the volume holographic grating includes the photopolymer holographic recording medium described in any of the above embodiments.

[0151] It is understandable that volume holographic recording gratings are fabricated by exposing photopolymer holographic recording media using the principle of light interference. Therefore, the holographic optical properties of the photopolymer holographic recording media determine the quality of the volume holographic recording grating.

[0152] As can be seen from the above, the volume holographic recording grating proposed in this application has high sensitivity, greater than 100 cm / mJ, and a diffraction efficiency greater than 95%, with an exposure amount less than 20 mJ / cm. 2 .

[0153] This application also provides a holographic optical element, the raw material of which includes the aforementioned photopolymer-type holographic recording medium. This holographic optical element includes, but is not limited to, a volume holographic grating.

[0154] It is understood that the holographic optical element proposed in this application, since it includes the aforementioned photopolymer holographic recording medium, also has the advantages of the photopolymer holographic recording medium of this application, and has optical performance with high diffraction efficiency, high sensitivity and high refractive index modulation rate.

[0155] This application also provides an optical device, including the holographic optical element as described above. This optical device includes, but is not limited to, head-up displays (HUDs), augmented reality (AR) devices, virtual reality (VR) devices, and photopolymer holographic storage optical discs. Photopolymer holographic storage optical discs can be erasable and rewritable, and can record in real time, making them suitable for storing large amounts of data and providing very fast data transfer speeds.

[0156] As can be seen from the above, the optical device proposed in this application, since it includes the aforementioned holographic optical element, also has the advantages of the holographic optical element in this application. The optical device has excellent optical performance, clear image, and can store a large amount of data.

[0157] The following describes the (meth)acrylate monomers, the preparation method of the (meth)acrylate monomers, and the photopolymer holographic recording medium containing (meth)acrylate monomers in this application with reference to specific embodiments.

[0158] Example 1

[0159] Synthesis of (meth)acrylate monomer G1

[0160]

[0161] Step S101: Under nitrogen protection, compound M1-1 (10 mmol), compound M2 (30 mmol), Cs2CO3 (30 mmol), 5 mol% PdCl2 (dppf), and 5 mol% 1,1'-bis(diphenylphosphine)ferrocene were dissolved in 20 mL of a mixed solvent of water and 1,4-dioxane (water: 1,4-dioxane = 1 / 4). The mixture was reacted at 120 °C for 24 hours. Excess solvent was removed by rotary evaporation, and the target product compound P1-1 was obtained by column chromatography.

[0162]

[0163] Step S102: Under ice bath conditions, compound P1-1 (10 mmol) and triethylamine (60 mmol) were dissolved in 10 mL of ethyl acetate. After stirring for 10 min, acryloyl chloride (90 mmol) was added dropwise to the reaction system to carry out the reaction. After the reaction was completed, dilute hydrochloric acid was added to remove excess acryloyl chloride. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution and deionized water. The organic phase was dried over anhydrous sodium sulfate and the excess solvent was removed by rotary evaporation. The mixture was then separated by column chromatography to obtain the (meth)acrylate monomer G1 of this application. The yield of G1 was 96%.

[0164] The characterization data are as follows:

[0165] 1H NMR (600MHz, CDCl3) δ7.55–7.45(m,12H),7.39–7.33(m,6H),7.33–7.27(m,6H),6.15–6.05(m,3H),5.8 7(s,3H),5.85(d,J=0.9Hz,3H),5.41(hept,J=1.0Hz,1H),4.30(t,J=7.1Hz,6H),3.28(t,J=7.1Hz,6H).

[0166] 13 C NMR (151MHz, CDCl3) δ166.70,140.27,139.37,138.46,136.62,131.49,128.63,128.23,128.16,128.02,127.04,66.70,58.58,33.98.

[0167] Example 2

[0168] Synthesis of (meth)acrylate monomer G2

[0169]

[0170] Step S101: Under nitrogen protection, compound M1-2 (10 mmol), compound M2 (30 mmol), K3PO4 (30 mmol), 1.5 mol% Pd(OAc)2 and 3 mol% XPhos were dissolved in 20 mL of a mixed solvent of water and tetrahydrofuran (water:tetrahydrofuran = 1 / 4). The mixture was reacted at 70 °C for 24 hours. Excess solvent was removed by rotary evaporation, and the target product compound P1-2 was obtained by column chromatography.

[0171]

[0172] Step S102: Under ice bath conditions, compound P1-2 (10 mmol) and pyridine (60 mmol) were dissolved in 10 mL of dichloromethane and stirred for 10 min. Then, methacryloyl chloride (90 mmol) was added dropwise to the reaction system to carry out the reaction. After the reaction was completed, dilute hydrochloric acid was added to remove excess methacryloyl chloride. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution and deionized water. The organic phase was dried over anhydrous sodium sulfate and the excess solvent was removed by rotary evaporation. The mixture was then separated by column chromatography to obtain the (meth)acrylate monomer G2 of this application. The yield of G2 was 96.8%.

[0173] The characterization data are as follows:

[0174] 1H NMR(600MHz, CDCl3)δ7.50(ddq,J=7.9,2.9,1.6Hz,12H),7.47–7.41(m,6H),7.35–7.26(m,6H),5.96(dd,J =7.8, 2.1Hz, 3H), 5.61 (dd, J = 15.4, 2.2Hz, 3H), 4.29 (t, J = 7.1Hz, 6H), 3.30 (t, J = 7.1Hz, 6H), 1.92 (s, 9H).

[0175] 13 C NMR (151MHz, CDCl3) δ167.40,141.32,139.83,136.21,135.82,134.07,131.42,129.27,128.34,128.15,125.62,66.40,35.47,17.99.

[0176] Example 3

[0177] Synthesis of (meth)acrylate monomer G3

[0178]

[0179] Step S101: Under nitrogen protection, compound M1-3 (10 mmol), compound M2 (24 mmol), Na2CO3 (30 mmol), 1.5 mol% Pd(PPh3)4 and 3 mol% PPh3 were dissolved in 10 mL of a mixed solvent of water and toluene (water:toluene = 1 / 4). The mixture was reacted at 110 °C for 24 hours. Excess solvent was removed by rotary evaporation, and the target product compound P1-3 was obtained by column chromatography.

[0180]

[0181] Step S102: Under ice bath conditions, compound P1-3 (10 mmol) and potassium carbonate (80 mmol) were dissolved in 15 mL of acetonitrile. After stirring for 10 min, acryloyl chloride (60 mmol) was added dropwise to the reaction system to carry out the reaction. After the reaction was completed, dilute hydrochloric acid was added to remove excess acryloyl chloride. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution and deionized water. The organic phase was dried over anhydrous sodium sulfate and the excess solvent was removed by rotary evaporation. The mixture was then separated by column chromatography to obtain the (meth)acrylate monomer G3 of this application. The yield of G3 was 97%.

[0182] The characterization data are as follows:

[0183] 1H NMR(600MHz, CDCl3)δ7.53–7.46(m,8H),7.40–7.33(m,4H),7.33–7.26(m,4H),6.14–6.03 (m,2H),5.87(d,J=0.7Hz,2H),5.84(d,J=0.9Hz,2H),4.30(t,J=7.1Hz,4H),3.28(s,4H).

[0184] 13 C NMR (151MHz, CDCl3) δ166.40,138.51,135.55,131.47,129.72,129.12,128.20,127.95,127.75,65.79,33.50.

[0185] Example 4

[0186] Synthesis of (meth)acrylate monomer G4

[0187]

[0188] Step S101: Under nitrogen protection, compound M1-4 (10 mmol), compound M2 (20 mmol), Cs2CO3 (30 mmol), 1.5 mol% Pd2(dba)3 and 3 mol% XPhos were dissolved in 20 mL of a mixed solvent of water and toluene (water:toluene = 1 / 4). The mixture was reacted at 110 °C for 24 hours. Excess solvent was removed by rotary evaporation, and the target product compound P1-4 was obtained by column chromatography.

[0189]

[0190] Step S102: Under ice bath conditions, compound P1-4 (10 mmol) and triethylamine (60 mmol) were dissolved in 10 mL of dichloromethane and stirred for 10 min. Then, methacryloyl chloride (60 mmol) was added dropwise to the reaction system to carry out the reaction. After the reaction was completed, dilute hydrochloric acid was added to remove excess methacryloyl chloride. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution and deionized water. The organic phase was dried over anhydrous sodium sulfate and the excess solvent was removed by rotary evaporation. The mixture was then separated by column chromatography to obtain the (meth)acrylate monomer G4 of this application. The yield of G4 was 97.4%.

[0191] The characterization data are as follows:

[0192] 1H NMR (600MHz, CDCl3) δ8.20–7.80(m,4H),7.69–7.54(m,4H),7.58–7.44(m,4H),7.41–7.20(m,4H),5.96(ddq,J=7.7,1. 9,0.9Hz,2H),5.61(ddq,J=15.4,2.0,1.1Hz,2H),4.29(t,J=7.1Hz,4H),3.30(t,J=7.1Hz,4H),1.94(t,J=1.0Hz,6H).

[0193] 13 C NMR (151MHz, CDCl3) δ167.41,145.77,141.16,138.73,136.60,136.18,129.44,128.20,126.14,65.98,33.46,18.27.

[0194] Example 5

[0195] Synthesis of (meth)acrylate monomer G5

[0196]

[0197] Step S101: Under nitrogen protection, compound M1-5 (10 mmol), compound M2 (24 mmol), K2CO3 (30 mmol), 1.5 mol% Pd(PPh3)2Cl2 and 1.5 mol% SPhos were dissolved in 20 mL of a mixed solvent of water and toluene (water:toluene = 1 / 4). The mixture was reacted at 110 °C for 24 hours. Excess solvent was removed by rotary evaporation, and the target product compound P1-5 was obtained by column chromatography.

[0198]

[0199] Step S102: Under ice bath conditions, compound P1-5 (10 mmol) and N,N-diisopropylethylamine (70 mmol) were dissolved in 10 mL of ethyl acetate. After stirring for 10 min, acryloyl chloride (60 mmol) was added dropwise to the reaction system to carry out the reaction. After the reaction was completed, dilute hydrochloric acid was added to remove excess acryloyl chloride. The mixture was washed successively with saturated NaCl solution, saturated NaHCO3 solution and deionized water. The organic phase was dried over anhydrous sodium sulfate and the excess solvent was removed by rotary evaporation. The mixture was then separated by column chromatography to obtain the (meth)acrylate monomer G5 of this application. The yield of G5 was 98%.

[0200] The characterization data are as follows:

[0201] 1H NMR (600MHz, CDCl3) δ7.92–7.69(m,4H),7.61–7.55(m,4H),7.55–7.50(m,4H),7.39–7.12(m,4H),6. 14–6.04(m,2H),5.88(d,J=0.6Hz,2H),5.85(t,J=0.7Hz,2H),4.51–4.07(m,4H),3.48–3.00(m,4H).

[0202] 13 C NMR (151MHz, CDCl3) δ166.85,144.34,143.58,135.36,131.46,129.44,128.18,127.76,127.62,127.29,65.79,33.52.

[0203] Example 6

[0204] Photopolymer-type holographic recording media 6-1 to 6-5 were prepared using the (meth)acrylate monomers described in Examples 1-5. The preparation method involved mixing all components thoroughly, filtering the mixture using a filter membrane, coating the resulting filtrate onto a substrate, and drying it in a darkroom at a humidity of 10%–85% and a temperature of 20°C–50°C to obtain the photopolymer-type holographic recording media. The specific components of photopolymer-type holographic recording media 6-1 to 6-5 are shown in Tables 1 to 5.

[0205] Table 1

[0206]

[0207]

[0208] Table 2

[0209]

[0210] Table 3

[0211]

[0212]

[0213] Table 4

[0214]

[0215] Table 5

[0216]

[0217]

[0218] Comparative Example 1

[0219] The composition is roughly the same as that of the photopolymer holographic recording medium 6-1 in Example 6, except that (meth)acrylate monomer G1 is not added in the comparative example, and 4-chlorostyrene is increased to 30 wt% to obtain a common photopolymer holographic recording medium.

[0220] Test case

[0221] (1) The refractive index of the (meth)acrylate monomers synthesized in Examples 1 to 5 was tested, and the results are shown in Table 6.

[0222] (2) The performance of the photopolymer holographic recording media 6-1 to 6-5 containing (meth)acrylate monomers in Examples 6 and the ordinary photopolymer holographic recording media of the comparative example were tested, and the results are shown in Table 7. During the test, different wavelengths of laser light were selected for exposure of each holographic recording medium in Example 6 according to the different photosensitive systems, and the exposure intensity was 3mW / cm². 2 .

[0223] The detection light source uses a 785nm wavelength solid-state laser that does not react with the recording medium. The detection light is incident on the exposure area from the Bragg angle. The transmitted light and diffracted light are monitored in real time by a photodetector. The single grating diffraction efficiency (η) and the photosensitivity (S) of the photopolymer holographic recording medium are calculated by formulas (1) to (3).

[0224]

[0225] In the formula, η is the diffraction efficiency, η max For the highest diffraction efficiency, I d For diffracted light, I t S represents transmitted light, S represents photosensitivity, E represents exposure energy, and ΔE represents the exposure energy required to achieve the highest diffraction efficiency.

[0226] Table 6 Refractive indices of the monomers synthesized in Examples 1-5

[0227]

[0228]

[0229] Table 7. Holographic performance parameters of the holographic recording media in Example 6 and the comparative example.

[0230]

[0231] In summary, as described in Tables 6 and 7, the (meth)acrylate monomers in Examples 1-5 of this application have high refractive indices. After polymerization with polymerizable monomers, they can effectively increase the refractive index of the writing monomer and further enhance the refractive index difference between the writing monomer and the film-forming resin. Furthermore, the photopolymer holographic recording medium containing the (meth)acrylate monomers in Examples 1-5 of this application has a diffraction efficiency greater than 95%, a sensitivity greater than 100 cm / mJ, and an exposure dose less than 20 mJ / cm. 2 Compared to the comparative example, it has lower exposure, higher diffraction efficiency and sensitivity, and superior holographic performance. (See also...) Figure 1 and Figure 2 As can be seen, the diffraction efficiency of the comparative holographic recording medium decreases after reaching its maximum value, while the diffraction efficiency of the holographic recording medium with added multifunctional (meth)acrylate monomers does not decrease after reaching its maximum value. This is because high diffraction efficiency usually requires the polymer chains to form a stable periodic structure. Multifunctional monomers, after polymerization, form a three-dimensional network cross-linked structure, which directly hinders chain migration. Therefore, the diffraction efficiency of the holographic recording medium can be maintained at a high value. On the other hand, monofunctional monomers, after polymerization, form a linear structure that is easy to migrate, thus the diffraction efficiency of the holographic recording medium will decrease.

[0232] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A (meth)acrylate monomer, characterized in that, Its structural formula is shown in any one of G1-G5: R1 represents methyl or hydrogen.

2. A method for preparing (meth)acrylate monomers as described in claim 1, characterized in that, Includes the following steps: Step S101: Under an inert environment, compound M1, target compound, and compound M2 are dissolved in a first solvent to obtain a first mixture, and the first mixture is subjected to a first treatment operation. The first mixture after the first treatment operation is separated to obtain compound P1. The first processing operation includes at least heating and stirring operations; the target compound includes a first catalyst, a ligand, and a base reagent; and the compound M1 is selected from compounds with the following structural formulas: Compound M2 is selected from compounds with the following structural formulas: The structural formula of compound P1 is shown in any of the following: Step S102: Dissolve the compound P1 and the acid-binding agent in a second solvent, and add compound M3 to react and obtain a second mixture after the reaction. Separate the second mixture to obtain the (meth)acrylate monomer. Wherein, compound M3 is acryloyl chloride or methacryloyl chloride.

3. The preparation method according to claim 2, characterized in that, The first solvent comprises at least one of toluene, dimethoxyethane, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, and 1,4-dioxane; or, the first solvent is a mixed solvent of water and an organic solvent, wherein the organic solvent comprises at least one of toluene, dimethoxyethane, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, and 1,4-dioxane. And / or, the second solvent comprises at least one of ethanol, petroleum ether, dichloromethane, chloroform, ethyl acetate, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide; And / or, the first catalyst comprises at least one of tetrakis(triphenylphosphine)palladium, bis(diphenylphosphine-ferrocene)palladium dichloride, palladium acetate, tris(dibenzylacetone)palladium, bis(triphenylphosphine)palladium dichloride, palladium chloride containing di-tert-butylphosphine-ferrocene ligand, bis(triphenylphosphine)palladium dichloride, bis(diphenylphosphine-ferrocene)nickel chloride, palladium on carbon, Bedford palladium catalyst, DHBOP monodentate phosphine ligand catalyst, palladium catalyst containing tert-butyl ligand, and Buchwald precatalyst; And / or, the alkaline reagent comprises at least one of potassium carbonate, sodium carbonate, cesium carbonate, potassium phosphate, potassium acetate, potassium fluoride, cesium fluoride, tetrabutylammonium fluoride, barium hydroxide, sodium hydroxide, and potassium trimethylsilanolate; And / or, the ligand comprises at least one of triphenylphosphine, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl, 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl, 1,3-bis(2,4,6-trimethylphenyl)imidazolium-2-ylidene, tricyclohexylphosphine, 1,1'-bis(diphenylphosphino)ferrocene, XPhos, and monodentate phosphine ligands; And / or, the acid-binding agent comprises at least one of triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, tetrabutylammonium bromide, potassium carbonate, ammonium carbonate, and sodium carbonate.

4. The preparation method according to claim 2, characterized in that, In step S101, based on the number of bromine groups in compound M1, the molar ratio of bromine groups in compound M1 to that in compound M2 is 1:(1~1.2); And / or, in step S101, the amount of the first catalyst is 0.5 to 5% of the molar amount of the compound M1, the amount of the ligand is 1 to 10% of the molar amount of the compound M1, and the molar ratio of the compound M1 to the base reagent is 1:(1 to 3). And / or, in step S102, the molar ratio of compound P1, compound M3 and acid-binding agent is 1:(1-3):(1-4) based on the number of hydroxyl groups in compound P1.

5. The preparation method according to claim 2, characterized in that, The reaction temperature in step S101 is 60-120℃, and the reaction time is 2-24 hours. And / or, in step S102, the reaction temperature of compound P1, compound M3 and acid-binding agent is 0°C.

6. A photopolymer-based holographic recording medium, characterized in that, Its raw materials contain the following components a)-h); Component a) A compound having multiple isocyanate reactive functional groups; Component b) Polyisocyanate group compounds; Component c) (meth)acrylate monomers; Component d) can polymerize monomers; Component e) Photosensitive initiation system; Component f) Chain transfer agent; Component g) optionally serves as a second catalyst; Component h) can be optionally added; Wherein, the (meth)acrylate monomer is at least one of the (meth)acrylate monomers G1-G5 according to claim 1.

7. The photopolymer-type holographic recording medium according to claim 6, characterized in that, The composition and content of the photopolymer-type holographic recording medium are as follows: Component a) 10–50 wt% of compounds having multiple isocyanate reactive functional groups; Component b) 10–50 wt% of polyisocyanate group compounds; Component c) (meth)acrylate monomers 1-30 wt%; Component d) can polymerize 10-40 wt% of monomers; Component e) Photoinitiator system 0.1–3 wt%; Component f) Chain transfer agent 0.1–3 wt%; Component g) Second catalyst 0.1-5 wt%; Component h) Additives 0.1-10 wt%.

8. The photopolymer-type holographic recording medium according to claim 6, characterized in that, The (meth)acrylate monomers account for 0.1–30 wt% of the total content of the photopolymer holographic recording medium; And / or, the isocyanate reactive functional group is a hydroxyl group, and the molar ratio of the hydroxyl group in component a) of the compound having a plurality of isocyanate reactive functional groups to the isocyanate functional group in component b) of the polyisocyanate group compound is 1:

1.

9. The photopolymer-type holographic recording medium according to claim 6, characterized in that, The isocyanate reactive functional group is a hydroxyl group; the compound having multiple isocyanate reactive functional groups includes compounds with a refractive index less than or equal to a first refractive index threshold and having two or more hydroxyl functional groups, wherein the first refractive index threshold is any value between 1.5 and 1.

55. And / or, the polyisocyanate-based compound includes compounds with a refractive index less than or equal to a second refractive index threshold and having two or more isocyanate groups; the second refractive index threshold is any value between 1.5 and 1.55; And / or, the polymerizable monomer is selected from at least one of alkenylnaphthalene compounds, alkenylanthracene compounds, alkenylbenzene compounds, acrylic compounds, methacrylic acid compounds, acrylate compounds, methacrylate compounds, N-vinylpyrrole, N-vinylcarbazole, N-vinylimidazol, N-vinylindole, N-vinylpyrrolidone, and trans-N-3-yntynebutenylcarbazole; And / or, the photoinitiating system includes a photosensitizer and a photoinitiator; And / or, the chain transfer agent is a thiol compound; And / or, the second catalyst is a tertiary amine catalyst and an organometallic catalyst; And / or, the additives include at least one of defoamers, leveling agents, plasticizers, and dehydrating agents.

10. The photopolymer-type holographic recording medium according to claim 9, characterized in that, The compound having multiple isocyanate reactive functional groups includes at least one of tetraethylene glycol, trimethylolethane, glycerol, triethanolamine, polyester polyol with a molecular weight of 200 to 2000, polycarbonate polyol, and polyether polyol. And / or, the polyisocyanate group compound includes at least one of hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tri(hexamethylene)isocyanate, butane-1,4-diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate; And / or, the chain transfer agent comprises at least one of dodecyl mercaptan, mercaptoethanol, hexamethylene mercaptan, phenylethyl mercaptan, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, and 4-methyl-4H-1,2,4-triazole-3-thiol; And / or, the second catalyst comprises at least one of the following: triethylenediamine, bis(dimethylaminoethyl) ether, dimethylethanolamine, 2-(2-dimethylaminoethoxy)ethanol, trimethylhydroxyethylpropanediamine, N,N-bis(dimethylaminopropyl)isopropanolamine, dibutyltin dilaurate, stannous octoate, potassium carboxylate catalysts, and bismuth carboxylate catalysts.

11. The photopolymer-type holographic recording medium according to claim 9, characterized in that, The photosensitizer includes at least one of cyanine dyes, fluorescein dyes, coumarin ketone dyes, nitrogen-containing aromatic heterocyclic compounds, aromatic amine compounds, and benzylidene cycloalkane ketone compounds; The photoinitiator includes aromatic ketone compounds, benzoin and its derivatives, benzoyl ketal, acylphosphine oxide, ammonium arylboronate, chromium salt, aryl diazonium salt, onium salt, organometallic compound, or at least one of these compounds; The mass ratio of the photosensitizer to the photoinitiator is (0.001-1):(0.1-3).

12. The photopolymer-type holographic recording medium according to claim 9, characterized in that, The defoamer is an organosilicon defoamer and / or a polymeric defoamer without organosilicon, and the content of the defoamer in the photopolymeric holographic recording medium is less than or equal to 3 wt%. And / or, the leveling agent is an organosilicon surface additive, and the leveling agent accounts for less than or equal to 3 wt% of the photopolymer holographic recording medium; And / or, the plasticizer is selected from at least one of toluene, xylene, dimethylformamide, dimethylacetamide, glycerol, and phthalates, and the plasticizer accounts for less than or equal to 3 wt% of the photopolymer holographic recording medium; And / or, the dehydrating agent includes at least one of p-toluenesulfonyl isocyanate and triethyl orthoformate, and the dehydrating agent accounts for less than or equal to 3 wt% of the photopolymer holographic recording medium.

13. A method for preparing a photopolymer-type holographic recording medium as described in any one of claims 6-12, characterized in that, Weigh the compound having multiple isocyanate reactive functional groups, the polyisocyanate group compound, the (meth)acrylate monomer, the polymerizable monomer, the photoinitiator system, the chain transfer agent, the second catalyst, and the additive into a container, and stir thoroughly until dissolved to form a mixed solution; The mixture solution was filtered using a filter membrane to obtain a second solution; The second solution is coated onto the substrate and dried to obtain the photopolymer holographic recording medium.

14. The preparation method according to claim 13, characterized in that, The drying process is carried out in a dark room with a humidity of 10% to 85% and a temperature of 20°C to 50°C.

15. A volume holographic recording grating, characterized in that, The photopolymer holographic recording medium used in the volume holographic recording grating includes the photopolymer holographic recording medium as described in any one of claims 6-12.

16. A holographic optical element, characterized in that, Its raw materials include the photopolymer type holographic recording medium as described in any one of claims 6 to 12.

17. An optical device, characterized in that, Includes the holographic optical element as described in claim 16.

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