Optical monomer, holographic recording medium, preparation method and related device

Abstract

The invention discloses an optical monomer, a holographic recording medium, a preparation method and a related device, the structural general formula of the optical monomer is as shown in G1-G6, the monomer is high in refractive index, the preparation method is simple, and further, the optical monomer with the structure is introduced into the photopolymer type holographic recording medium, so that the photopolymer type holographic recording medium is prepared. The invention further provides a preparation method of the holographic recording medium, a volume holographic grating containing the holographic recording medium, a holographic optical element containing the holographic recording medium and an optical device containing the holographic recording medium.

Description

Technical Field

[0001] This application relates to the field of holographic materials technology, and in particular to an optical monomer, a holographic recording medium, a preparation method, and related apparatus. Background Technology

[0002] Photopolymers used to fabricate holographic recording media typically include components such as photosensitive dyes, initiators, chain transfer agents, writing monomers, film-forming resins, and plasticizers. Photopolymers utilize light to polymerize the writing monomers, which then combine with the film-forming resin to form a refractive index-modulated phase-type holographic grating, thus achieving holographic recording. Specifically, when the writing monomers located in the coherent bright region are consumed and their concentration decreases, unreacted writing monomers located in the coherent dark region rapidly migrate to the coherent bright region, squeezing the film-forming resin from the bright region into the dark region. Ultimately, this results in the refractive index of the coherent bright region approaching that of the writing monomers, and the refractive index of the coherent dark region approaching that of the film-forming resin, thereby forming a refractive index-modulated phase-type volume holographic grating.

[0003] Therefore, improving the performance of photopolymers generally requires the base resin to have a lower refractive index and the writing monomer to have a higher refractive index to increase the refractive index difference between the two. However, the refractive index of the writing monomer currently available for photopolymers is usually below 1.6, resulting in a small difference in refractive index between the recording monomer and the film-forming resin (usually 0.1 to 0.2). Consequently, the refractive index modulation of the resulting recording grating is low (Δn < 0.07), which further reduces the grating's ability to control incident light, leads to excessive light energy loss, and causes low diffraction efficiency and unclear imaging in optical devices. Summary of the Invention

[0004] This application aims to provide an optical monomer with a high refractive index to solve the problem of performance degradation in photopolymer holographic recording media caused by the small difference in refractive index between the writing monomer and the film-forming resin.

[0005] In a first aspect, this application provides an optical unit, the general structural formula of which is shown in any of the following:

[0006]

[0007] Wherein, R1 represents methyl or hydrogen, and R2 represents hydrogen or a substituent on the benzene ring, wherein the substituent is selected from phenyl, Halogen, C1-C4 alkyl, A1 represents C1-C4 alkyl, and n is a positive integer, n = 0 to 9.

[0008] As can be seen from the above technical solutions, the optical monomer provided in the first aspect of this application has an aromatic thioacetal structure. The high electronic polarizability and molecular packing effect of sulfur atoms have a significant impact on the refractive index of the monomer. Moreover, based on the presence of multiple benzene rings, the conjugation effect superimposed on the polarization of sulfur, giving the monomer a high refractive index, which is greater than 1.6 and less than 1.75.

[0009] Secondly, this application provides a method for preparing the aforementioned optical monomer, comprising:

[0010] Compound M1 and an acid reagent were dissolved in an organic solvent. After performing the first treatment operation, compound M2 was added to react and compound P1 was obtained.

[0011] The first processing operation includes at least a heating operation and a stirring operation, and the compound M1 is selected from compounds with the following general structural formula: R2 represents a hydrogen atom or a substituent on the benzene ring, the substituent being selected from... Halogen, C1-C4 alkyl, A1 represents C1-C4 alkyl;

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

[0013] The general structural formula of compound P1 is shown below:

[0014] As can be seen from the above technical solutions, the method for preparing optical monomers provided in the second aspect of this application constructs the core structure of dithioacetal in one step. The synthesis route is short, the raw materials are cheap and readily available, the steps are simple and easy to operate, and it is convenient for large-scale production.

[0015] Thirdly, this application provides a photopolymer-type holographic recording medium, the raw material of which comprises the following components a)-h).

[0016] Component a) A compound having multiple isocyanate reactive functional groups;

[0017] Component b) Polyisocyanate group compounds;

[0018] Component c) Optical monomer;

[0019] Component d) can polymerize monomers;

[0020] Component e) Photosensitive initiation system;

[0021] Component f) Chain transfer agent;

[0022] Component g) optionally a catalyst;

[0023] Component h) can be optionally added;

[0024] The optical monomer is at least one of the aforementioned optical monomers G1-G6.

[0025] As can be seen from the above technical solution, this application provides a photopolymer-type holographic recording medium containing the aforementioned optical monomers. By introducing high-refractive-index optical monomers into the photopolymer-type holographic recording medium, the refractive index difference between the recording monomers and the film-forming resin is effectively increased, thereby obtaining a photopolymer-type holographic recording medium with excellent properties such as high sensitivity and high diffraction efficiency. Specifically, the diffraction efficiency of the photopolymer-type holographic recording medium is greater than 95%, the sensitivity is greater than 100 cm / mJ, and the exposure dose is less than 20 mJ / cm. 2 .

[0026] Fourthly, this application provides a method for preparing the aforementioned photopolymer-type holographic recording medium, comprising:

[0027] Weigh the compound having multiple isocyanate reactive functional groups, the polyisocyanate group compound, the optical monomer, the polymerizable monomer, the photoinitiator system, the chain transfer agent, the catalyst and the additive into a container, and stir thoroughly until dissolved to form a mixed solution;

[0028] The mixture solution is filtered using a filter membrane to obtain a first solution;

[0029] The first solution is coated onto a substrate and dried to obtain the photopolymer holographic recording medium.

[0030] As can be seen from the above technical solutions, the preparation method of the photopolymer-based holographic recording medium provided in this application is simple to operate and low in cost. It can ensure the 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 filtration step can effectively remove impurities, reduce light scattering, and improve the storage stability and imaging quality of the holographic medium.

[0031] Fifthly, this application provides a volume holographic recording grating, the raw material of which includes the photopolymer type holographic recording medium as described above.

[0032] Sixthly, this application provides a holographic optical element, the raw material of which includes the aforementioned photopolymer-type holographic recording medium.

[0033] In a seventh aspect, this application provides an optical device including the holographic optical element as described above.

[0034] As can be seen from the above technical solutions, this application also provides a related device made using the aforementioned photopolymer holographic recording medium, based on the fact that the photopolymer holographic recording medium has a sensitivity greater than 100 cm / mJ and an exposure dose less than 20 mJ / cm. 2 It also has excellent properties such as a recording grating diffraction efficiency greater than 95%.

[0035] Furthermore, based on a sensitivity greater than 100 cm / mJ, only extremely low exposure energy is required to form a stable grating, which can shorten exposure time, reduce laser power requirements, increase recording speed, and reduce energy consumption efficiency, making it suitable for dynamic recording and low-power devices. Based on an exposure energy below 20 mJ / cm... 2 This demonstrates that only a small amount of light energy is needed to complete the curing and photopolymerization of the photopolymer holographic recording medium, thus avoiding overheating and deformation of the material caused by high-energy exposure. Based on a diffraction efficiency greater than 95%, it indicates that almost all incident light energy is diffracted to the target direction by the grating, thereby reducing light energy loss and resulting in a clearer image. Therefore, target devices (such as volume holographic recording gratings, optical elements, and optical devices) fabricated using photopolymer holographic recording media possess optical properties such as high recording speed and clear imaging. Attached Figure Description

[0036] Figure 1 The exposure characteristic curves of photopolymer holographic recording media 7-1, 7-3, and 7-5 in Embodiment 7 of this application are shown.

[0037] Figure 2 The exposure characteristic curves of the photopolymer holographic recording media in Comparative Examples 1 and 3 of this application are shown. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] It should be understood that photopolymer-based holographic recording media materials used for holographic recording achieve holographic recording by using light to polymerize writing monomers, which then form a refractive index-modulated phase-type holographic grating with the film-forming resin. Specifically, when the writing monomers in the coherent bright region are consumed and their concentration decreases, the unreacted writing monomers in the coherent dark region rapidly migrate to the coherent bright region, squeezing the film-forming resin in the bright region into the coherent dark region. Ultimately, the refractive index of the coherent bright region approaches the refractive index of the writing monomers, and the refractive index of the coherent dark region approaches the refractive index of the film-forming resin, thus forming a refractive index-modulated phase-type volume holographic grating.

[0044] 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 in order to increase the difference in refractive index between the two.

[0045] However, the refractive index of the writing monomers currently used in photopolymers is typically below 1.6, resulting in a small difference in refractive index between the writing monomer and the film-forming resin (typically 0.1–0.2). This leads to a small difference in refractive index between the recording monomer and the film-forming resin (typically 0.1–0.2), resulting in a low refractive index modulation degree (Δn<0.07) in the resulting recording grating. This further reduces the grating's ability to control incident light, causing excessive light energy loss and resulting in low diffraction efficiency and unclear imaging of optical devices, failing to meet the growing user demands.

[0046] Based on this, this application provides an optical monomer as a component of a writing monomer, the general structural formula of which is shown in any of the following:

[0047]

[0048] Wherein, R1 represents methyl or hydrogen, and R2 represents hydrogen or a substituent on the benzene ring, with the substituent selected from phenyl, ... Halogen, C1-C4 alkyl, A1 represents C1-C4 alkyl, and n is a positive integer, n = 0 to 9.

[0049] In this embodiment, the optical monomer has an aromatic thioacetal structure. The high electronic polarizability and molecular packing effect of sulfur atoms significantly affect the refractive index of the monomer. Moreover, due to the presence of multiple benzene rings, the conjugation effect superimposed on the polarization of sulfur, further increasing the refractive index of the monomer. Therefore, the entire monomer molecule exhibits an extremely high refractive index, greater than 1.6 and less than 1.75, which can effectively match common photosensitive resin systems, reduce light scattering loss during holographic recording, and improve 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.

[0050] In some specific examples, the optical monomer can be a compound having the following structural formula:

[0051]

[0052] This application also provides a method for preparing the above-mentioned optical monomer, including:

[0053] Step S1: Dissolve compound M1 and an acid reagent in an organic solvent, perform the first treatment operation, then add compound M2 to react and obtain compound P1. The first treatment operation includes at least heating and stirring. Compound M1 is selected from compounds with the following general structural formula: R2 represents a hydrogen atom or a substituent on the benzene ring, and the substituent is selected from... Halogen, C1-C4 alkyl, where A1 represents C1-C4 alkyl. Compound M2 is selected from compounds with the following general structural formula: The general structural formula of compound P1 is shown below:

[0054] It is understandable that in step S1, the thiol (i.e., compound M1), after being pre-activated by the acid reagent, exhibits stronger nucleophilicity and further undergoes a thioacetalization reaction with the aldehyde (i.e., compound M2) to generate a thioacetal (i.e., compound P1). This step typically requires controlling the addition rate of the aldehyde (i.e., compound M2) to avoid direct contact between the aldehyde (i.e., compound M2) and the high-concentration acid reagent, which could trigger a self-condensation side reaction and reduce the formation of byproducts. Therefore, compound M2 needs to be slowly added dropwise to the reaction system. Specifically, compound M2 can also be dissolved in an organic solvent and then slowly added dropwise to the reaction system.

[0055] The first processing operation includes at least a heating operation and a stirring operation. The heating operation and the stirring operation can be performed simultaneously or separately. For example, the heating operation can be performed while stirring, or the stirring operation can be performed for a period of time before the heating operation is performed. This application does not limit the specific operation.

[0056] In some embodiments, the thioacetalization reaction is performed at 20°C-80°C for 0.5-36 hours with optimal results. This is understandable because, on the one hand, excessively high reaction temperatures may trigger oxidation side reactions of the thiol (i.e., compound M1), leading to decreased reaction selectivity; conversely, excessively low temperatures result in low molecular collision frequencies, significantly reduced reaction rates, and prolonged reaction times. On the other hand, the reaction temperature is also related to the selection of the reaction substrate and solvent, such as the stability or boiling point of the reaction substrate (e.g., compound M1).

[0057] In some specific examples, the molar ratio of compound M1, acid reagent and compound M2 is 2:(1-2):(1-1.2).

[0058] Typical, but not limiting, molar ratios of compound M1, acid reagent, and compound M2 may be, for example, 2:1:1, 2:1.5:1, or 2:2:1.2.

[0059] Acid reagents include, but are not limited to, one or more of the following: p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, camphorsulfonic acid, naphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, sulfosalicylic acid, citric acid, acetic acid, formic acid, phosphoric acid, anhydrous hydrogen peroxide, tetrafluoroboric acid, trifluoroacetic acid, pentafluoroacetic acid, heptafluoropropionic acid, and phosphoric acid.

[0060] It should be understood that in the thioacetal reaction, the acid reagent has the functions of activating thiols (i.e., compound M1) and aldehydes (i.e., compound M2), promoting the reaction process, and inhibiting the occurrence of side reactions (such as thiols oxidation reaction and aldehyde self-condensation reaction).

[0061] In addition, organic solvents include, but are not limited to, one or more of methanol, ethanol, petroleum ether, dichloromethane, chloroform, ethyl acetate, tetrahydrofuran, acetonitrile, benzene, toluene, N,N-dimethylformamide, dimethyl sulfoxide, dimethoxyethane, and 1,4-dioxane.

[0062] It is understood that the organic 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, thereby promoting molecular collisions between compounds M1 and M2 to generate new compounds. It should be noted that the solvents described above are merely illustrative, and the solvents that can be used in this application are not limited to these.

[0063] For example, 2 equivalents of compound M1 and 1-2 equivalents of p-toluenesulfonic acid were dissolved in ethyl acetate. The reaction system was heated to 20-80°C. 1 equivalent of compound M2 was dissolved in ethyl acetate and slowly added dropwise to the above reaction system. The reaction was continued with stirring for 0.5-36 hours. After the reaction was completed, sufficient triethylamine was added to quench the reaction, and the organic phase was extracted three times. The organic phase was dried with anhydrous sodium sulfate, excess solvent was removed by rotary evaporation, and compound P1 was obtained by column chromatography.

[0064] It is also understood that in step S1, the order of adding thiol (i.e., compound M1) and aldehyde (i.e., compound M2) can be changed. In other words, the aldehyde (i.e., compound M2) and acid reagent can be dissolved in the first solvent first, and then the thiol (i.e., compound M1) can be added. With the other conditions unchanged, compound P1 can also be obtained. This application does not impose any restrictions on this.

[0065] The preparation of an optical monomer with the general structural formula G1 includes the following steps in addition to step S1:

[0066] Step S2: Dissolve compound P1 and an acid-binding agent in an organic solvent, and add compound M3 to react, yielding optical monomer G1. Compound M3 is acryloyl chloride or methacryloyl chloride.

[0067] The content of step S1 is as described above and will not be repeated here. It can be understood that in step S2, 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, ultimately yielding the optical monomer G1. In some specific examples, the reaction is usually controlled at 0°C (i.e., in an ice bath). Compound M3 is added dropwise to the mixed solution of compound P1 and the acid-binding agent at 0°C to avoid local overheating or excessive concentration leading to side reactions. A reaction time of 0.5 h to 3 h typically yields optimal reaction results.

[0068] 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.

[0069] 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 also usually used in excess. Specifically, in some examples, the molar ratio of compound P1, acid-binding agent, and compound M3 is 1:(1-4):(1-3).

[0070] Typical, but not limiting, molar ratios of compound P1, acid-binding agent, and compound M3 can be, for example, 1:4:2, 1:4:3, 1:3:3, 1:3:2, and 1:3.5:2.5.

[0071] In some specific examples, the reaction is more effective when the reaction solvent in this step is any one of dichloromethane, trichloromethane, and ethyl acetate.

[0072] For example, 1 equivalent of compound P1 and 2-4 equivalents of triethylamine were dissolved in dichloromethane under ice bath conditions. After stirring for 10 min, 1-3 equivalents of acryloyl chloride or methacryloyl chloride were added dropwise to the mixed solution of compound P1 and triethylamine at 0 °C. After the reaction was complete, 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 optical monomer G1 was obtained by column chromatography.

[0073] The preparation of optical monomers with the general structural formula G3 or G4 includes the following steps in addition to step S1:

[0074] Step S3: Dissolve compound P1 in the first solvent, perform the second treatment operation, add a deprotonating agent, and after a period of time, add compound M5 to obtain optical monomers G3 or G4. The second treatment operation includes at least a cooling operation and a stirring operation, and compound M5 is 3-bromo-1-propene or 3-bromo-1-propyne.

[0075] The content of step S1 is as described above and will not be repeated here. It can be understood that the deprotonating agent deprotonates the hydroxyl group in compound P1, forming a more reactive oxonium intermediate I. Oxonium intermediate I further attacks the carbon atom in the brominated hydrocarbon (i.e., compound M5) directly bonded to the halogen atom, and the bromide ion leaves as a leaving group, thereby yielding the dithiocarbamate monomer G3 or G4. It can also be understood that step S3, by converting compound P1 into the more reactive oxonium intermediate I, makes the reaction substrate (i.e., compound P1) more reactive and accelerates the reaction efficiency.

[0076] The second processing operation includes at least a cooling operation and a stirring operation. The cooling operation and the stirring operation can be performed simultaneously or separately. For example, the cooling operation can be performed while stirring, or the stirring operation can be performed for a period of time before the cooling operation is performed. This application does not limit the operation.

[0077] It should be noted that deprotonating agents include, but are not limited to, one or more of organometallic bases, metal amino compounds, metal alkoxides and metal hydrides, inorganic bases and organic bases.

[0078] Organometallic bases include, but are not limited to, alkyllithium reagents, aryllithium reagents, and aminolithium reagents. Typically, when using organometallic bases and metal amino compounds, the reaction must be carried out under anhydrous and oxygen-free conditions, and they are usually added dropwise to the reaction system at -78°C. Further, alkyllithium reagents include at least n-butyllithium and tert-butyllithium, aryllithium reagents include at least phenyllithium, and aminolithium reagents include at least diisopropylaminolithium and hexamethyldisilaminolithium. Metal amino compounds include, but are not limited to, sodium amino, potassium amino, and bis(trimethylsilyl)aminosodium. Metal alkoxides include, but are not limited to, sodium methoxide, sodium ethoxide, potassium tert-butoxide, and sodium tert-butoxide; metal hydrides include, but are not limited to, sodium hydride and potassium hydride; inorganic bases include, but are not limited to, potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, and potassium phosphate; and organic bases include, but are not limited to, triethylamine, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and tetramethylsilyltrifluoromethanesulfonate.

[0079] It should be further understood that when using deprotonating agents to deprotonate, it is necessary to determine whether the reaction needs to be carried out in an inert environment based on factors such as the different types of deprotonating agents and the properties of the reaction substrate. For example, inert gas protection can be used, including but not limited to nitrogen and argon. In other words, those skilled in the art can provide inert protection for the reaction according to actual needs, and this application does not limit it.

[0080] It should be noted that deprotonation reactions typically need to be carried out at low temperatures (-80℃ to 0℃). The choice of reaction temperature depends on the selection of the deprotonating agent, the stability and activity of the reaction substrate, and the melting point of the reaction solvent. After the deprotonation reaction is completed, the temperature can be raised according to actual needs (e.g., the activity of the reaction substrate, the reaction rate, etc.). Specifically, when organometallic bases and metal amino compounds (e.g., n-butyllithium) are used as deprotonating agents, the deprotonation reaction usually needs to be carried out at -30 to -80℃ in an inert environment to obtain better reaction results, suppress the generation of side reactions, and improve the regioselectivity of the reaction. When metal alkoxides and metal hydrides (e.g., sodium hydride, sodium methoxide, etc.) are used as deprotonating agents, the deprotonation reaction is usually carried out at 0℃ (i.e., in an ice bath), and the reaction time is usually 0.5h to 10h. It can be understood that the reaction time is related to the amount of deprotonating agent and the activity of the reaction substrate, etc., which are not limited in this application.

[0081] It should also be noted that the deprotonating agent should be added to the reaction system in batches and slowly to avoid a violent reaction that could cause injury to the sprayed material and personnel. Furthermore, protonated solvents, such as methanol, ethanol, isopropanol, acetic acid, and water, should be avoided in the deprotonation reaction. Therefore, it can be understood that the aforementioned organic solvents include the first solvent, which does not include protonated solvents.

[0082] In some specific examples, the molar ratio of compound P1, the deprotonating agent, and compound M5 is 1:(1 to 1.5):(1 to 1.5).

[0083] Typical, but not limiting, molar ratios of compound P1, the deprotonating agent, and compound M5 can be, for example, 1:1:1, 1:1.2:1.2, 1:1.5:1.3, 1:1.3:1.5, and 1:1.5:1.5.

[0084] For example, under ice bath conditions, 1 equivalent of compound P1 is dissolved in tetrahydrofuran, and 1–1.5 equivalents of deprotonating agent are slowly added. After stirring for 0.5–10 h, 1–1.5 equivalents of 3-bromo-1-propene or 3-bromo-1-propyne are added dropwise. After the addition is complete, stirring is continued for 0.5–10 h. After the reaction is complete, dilute hydrochloric acid is slowly added dropwise to quench the reaction, excess solvent is removed by rotary evaporation, and the optical monomer with the structural formula G3 or G4 is obtained by column chromatography.

[0085] The preparation of optical monomers with a general structural formula of G2, G5, or G6 includes the following steps in addition to step S1:

[0086] Step S4: Dissolve compound P1 in the first solvent, perform the second treatment operation, add a deprotonating agent, and after a period of time, add compound M4 to obtain compound P2. The second treatment operation includes at least a cooling operation and a stirring operation. The general structural formula of compound M4 is: The general structural formula of compound P2 is: n is a positive integer, and n = 0 to 9.

[0087] The content of step S1 is as described above and will not be repeated here. It can be understood that the reaction principle of step S4 is similar to that of step S3, both of which involve converting compound P1 into the oxygen anion intermediate I before proceeding with the reaction. The difference lies in the reaction substrate, i.e., using compound M4 or compound M5. Therefore, the relevant content can be referred to step S3 and will not be repeated here.

[0088] In some specific examples, the molar ratio of compound P1, the deprotonating agent, and compound M4 is 1:(1 to 1.5):(1 to 1.5).

[0089] Typical, but not limiting, molar ratios of compound P1, the deprotonating agent, and compound M4 can be, for example, 1:1:1, 1:1.2:1.2, 1:1.5:1.3, 1:1.3:1.5, and 1:1.5:1.5.

[0090] For example, 1 equivalent of compound P1 was dissolved in dichloromethane, and 1 equivalent of sodium hydride was slowly added at 0°C. After stirring for 0.5–10 h, 1–1.5 equivalents of compound M4 were added dropwise to the reaction system. After the addition was complete, the reaction was continued for another 0.5–10 h. After the reaction was complete, dilute hydrochloric acid was slowly added dropwise to quench the reaction, excess solvent was removed by rotary evaporation, and compound P2 was obtained by column chromatography.

[0091] Specifically, the preparation of an optical monomer with the general structural formula G2 includes the following steps in addition to steps S1 and S4:

[0092] Step S5: Dissolve compound P2 and an acid-binding agent in an organic solvent, and add compound M3 to react, yielding optical monomer G2. Compound M3 is acryloyl chloride or methacryloyl chloride.

[0093] The contents of steps S1 and S4 are as described above and will not be repeated here. It should be noted that the reaction principle and conditions of step S5 are the same as those of step S2, only the reaction substrate is different (i.e., compound P1 or compound P2). The relevant contents can be referred to step S2 and will not be repeated here.

[0094] In some specific examples, the molar ratio of compound P2, acid-binding agent and compound M3 is 1:(1-4):(1-3).

[0095] Typical, but not limiting, molar ratios of compound P2, acid-binding agent, and compound M3 can be, for example, 1:4:2, 1:4:3, 1:3:3, 1:3:2, and 1:3.5:2.5.

[0096] Specifically, the preparation of optical monomers with the general structural formula G5 or G6 includes the following steps in addition to steps S1 and S4:

[0097] Step S6: Dissolve compound P2 in the first solvent, perform the second treatment operation, add a deprotonating agent, and after a period of time, add compound M5 to obtain optical monomers G5 or G6. The second treatment operation includes at least a cooling operation and a stirring operation, and compound M5 is 3-bromo-1-propene or 3-bromo-1-propyne.

[0098] It should be noted that the reaction principle and conditions of step S6 are the same as those of step S3, only the reaction substrate is different (i.e., compound P1 or compound P2). The relevant content can be referred to step S3, and will not be repeated here.

[0099] In some specific examples, the molar ratio of compound P2, the deprotonating agent, and compound M5 is 1:(1 to 1.5):(1 to 1.5).

[0100] Typical, but not limiting, molar ratios of compound P2, the deprotonating agent, and compound M5 can be, for example, 1:1:1, 1:1.2:1.2, 1:1.5:1.3, 1:1.3:1.5, and 1:1.5:1.5.

[0101] In this embodiment, the synthesis route of the optical monomer is short, the raw materials are cheap and readily available, the preparation method is simple and easy to operate, and the yield of the optical monomer is high, reaching more than 95%.

[0102] This application also provides a photopolymer holographic recording medium, including a writing monomer, which includes an optical monomer and a polymerizable monomer.

[0103] It should be understood that the refractive index of the optical element is positively correlated with the refractive index of the writing element; that is, when the refractive index of the optical element is high, the refractive index of the resulting writing element is also high.

[0104] Furthermore, in some embodiments, the raw material of the photopolymer-type holographic recording medium comprises the following components a)-h):

[0105] Component a) A compound having multiple isocyanate reactive functional groups.

[0106] Component b) Polyisocyanate group compounds,

[0107] Component c) at least one of the aforementioned optical monomers G1-G6,

[0108] Component d) can polymerize monomers.

[0109] Component e) Photosensitive initiation system,

[0110] Component f) Chain transfer agent,

[0111] Component g) optionally a catalyst,

[0112] Component h) can be optionally added.

[0113] Among them, compounds with multiple isocyanate reactive functional groups and polyisocyanate group compounds form film-forming resins.

[0114] In this embodiment, an optical monomer with a high refractive index is used as a component of the writing monomer, thereby allowing for a greater refractive index difference between the writing monomer and the film-forming resin. This results in a photopolymer-type holographic recording material possessing excellent properties such as high sensitivity and high diffraction efficiency. Specifically, in some examples, the photopolymer-type holographic recording medium has a sensitivity greater than 100 cm / mJ, a recording grating diffraction efficiency greater than 95%, and an exposure dose less than 20 mJ / cm. 2 .

[0115] More specifically, in some examples, the composition and content of photopolymer-type holographic recording media are as follows:

[0116] Component a) 10 wt% to 50 wt% of compounds having multiple isocyanate reactive functional groups.

[0117] Component b) Polyisocyanate group compound 10wt%–50wt%,

[0118] Component c) Optical monomers 1wt%–30wt%,

[0119] Component d) can polymerize monomers ranging from 10 wt% to 40 wt%.

[0120] Component e) Photoinitiator system 0.1wt%~3wt%,

[0121] Component f) Chain transfer agent 0.1 wt% to 3 wt%,

[0122] Component g) Catalyst 0.1wt%~5wt%,

[0123] Component h) Additives: 0.1 wt% to 10 wt%.

[0124] Specifically, the content of component a) can be, for example, 10 wt%, 20 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, and 50 wt%, etc.; the content of component b) can be, for example, 10 wt%, 20 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, and 50 wt%, etc.; the content of component c) can be, for example, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, and 30 wt%, etc.; the content of component d) can be, for example, 10 wt%, 20 wt%, 30 wt%, 35 wt%, and 40 wt%, etc.; and the content of component e) can be, for example, 0.1 wt%, 0.5 wt%, etc. The content of component f) can be, for example, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, and 3wt%, etc.; the content of component g) can be, for example, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, and 5wt%, etc.; and the content of component h) can be, for example, 0.1wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, and 10wt%, etc.

[0125] More specifically, in some optional examples, the photopolymer-type holographic recording medium containing optical monomers comprises the following components in the following amounts: component a) 10 wt% of a compound having multiple isocyanate reactive functional groups, component b) 30 wt% of a polyisocyanate-based compound, component c) 30 wt% of an optical monomer, component d) 20 wt% of a polymerizable monomer, component e) 1 wt% of a photoinitiator system, component f) 1 wt% of a chain transfer agent, component g) 1 wt% of a catalyst, and component h) 7 wt% of an additive.

[0126] In some optional examples, the photopolymer-type holographic recording medium containing optical monomers comprises the following components in the following amounts: component a) 25 wt% of a compound having multiple isocyanate reactive functional groups, component b) 32 wt% of a polyisocyanate-based compound, component c) 3 wt% of an optical monomer, component d) 24 wt% of a polymerizable monomer, component e) 3 wt% of a photoinitiator system, component f) 3 wt% of a chain transfer agent, component g) 3 wt% of a catalyst, and component h) 7 wt% of an additive.

[0127] In some optional examples, the photopolymer holographic recording medium containing optical monomers comprises the following components in the following amounts: component a) 50 wt% of a compound having multiple isocyanate reactive functional groups, component b) 15 wt% of a polyisocyanate group compound, component c) 2 wt% of optical monomers, component d) 23 wt% of polymerizable monomers, component e) 1 wt% of a photoinitiator system, component f) 1 wt% of a chain transfer agent, component g) 2 wt% of a catalyst, and component h) 6 wt% of additives.

[0128] In some optional examples, the photopolymer-type holographic recording medium containing optical monomers comprises the following components in the following amounts: component a) 24 wt% of a compound having multiple isocyanate reactive functional groups, component b) 15 wt% of a polyisocyanate-based compound, component c) 1 wt% of an optical monomer, component d) 40 wt% of a polymerizable monomer, component e) 3 wt% of a photoinitiator system, component f) 3 wt% of a chain transfer agent, component g) 5 wt% of a catalyst, and component h) 9 wt% of an additive.

[0129] In some optional examples, the photopolymer-type holographic recording medium containing optical monomers comprises the following components in the following amounts: component a) 10 wt% of a compound having multiple isocyanate reactive functional groups, component b) 50 wt% of a polyisocyanate-based compound, component c) 20 wt% of optical monomers, component d) 10 wt% of polymerizable monomers, component e) 2.9 wt% of a photoinitiator system, component f) 0.1 wt% of a chain transfer agent, component g) 2 wt% of a catalyst, and component h) 5 wt% of additives.

[0130] In some optional examples, the photopolymer-type holographic recording medium containing optical monomers comprises the following components in the following amounts: component a) 33 wt% of a compound having multiple isocyanate reactive functional groups, component b) 21.9 wt% of a polyisocyanate-based compound, component c) 20 wt% of an optical monomer, component d) 11 wt% of a polymerizable monomer, component e) 2 wt% of a photoinitiator system, component f) 2 wt% of a chain transfer agent, component g) 0.1 wt% of a catalyst, and component h) 10 wt% of an additive.

[0131] In some optional examples, the photopolymer-type holographic recording medium containing optical monomers comprises the following components in the following amounts: component a) 25 wt% of a compound having multiple isocyanate reactive functional groups, component b) 30 wt% of a polyisocyanate-based compound, component c) 10 wt% of an optical monomer, component d) 25 wt% of a polymerizable monomer, component e) 0.2 wt% of a photoinitiator system, component f) 0.8 wt% of a chain transfer agent, component g) 3 wt% of a catalyst, and component h) 6 wt% of an additive.

[0132] In some optional examples, the photopolymer-type holographic recording medium containing optical monomers comprises the following components in the following amounts: component a) 35 wt% of a compound having multiple isocyanate reactive functional groups, component b) 15 wt% of a polyisocyanate-based compound, component c) 21 wt% of optical monomers, component d) 28.6 wt% of polymerizable monomers, component e) 0.1 wt% of a photoinitiator system, component f) 0.1 wt% of a chain transfer agent, component g) 0.1 wt% of a catalyst, and component h) 0.1 wt% of an additive.

[0133] 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.

[0134] In some embodiments, the optical monomer accounts for 0.1 wt% to 30 wt% of the total content of the photopolymer holographic recording medium.

[0135] Typically, but not limitingly, the content of optical 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.

[0136] In this embodiment, the content of optical monomers ranges from 0.1 to 30 wt%, ensuring 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.

[0137] 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.

[0138] 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.

[0139] 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 and the high-refractive-index writing monomer (i.e., including the aforementioned optical monomer) form a significant refractive index difference (Δn≥0.1), 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] In specific examples, vinylanthracene compounds may be selected from 2-vinylanthracene, 9-vinylanthracene, etc.

[0148] In specific examples, vinylnaphthalene compounds can be selected from 1-vinylnaphthalene, 2-vinylnaphthalene, etc.

[0149] 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.

[0150] 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.

[0151] In some examples, the mass ratio of photosensitizer to photoinitiator is (0.001–1):(0.1–3). Typical, but not limiting, the mass ratio of photosensitizer to photoinitiator can be 0.001–0.1, 0.001–3, 1:0.1, 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, or 1:3, etc.

[0152] 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.

[0153] 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.

[0154] 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, basic orange 21, darone red, pyrrole red Y, basic red 29, quinaldinium red, crystal violet, brilliant green, pyrimethium I, azurite A, crystal violet cyanocyanate, malachite green cyanocyanate, etc.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] It is understandable that the molecular weight of the polymerized optical monomers and 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.

[0160] As a catalyst, the catalyst can effectively increase the reaction rate of the relevant components and the consumption rate of the relevant components after exposure, thereby quickly forming the concentration difference of monomers in the bright and dark areas and realizing the phase-type volume holographic grating with refractive index modulation.

[0161] In some embodiments, the 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] This application also provides a method for preparing a photopolymer-based holographic recording medium, the method comprising:

[0171] 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.

[0172] Step S202: Filter the mixture solution using a filter membrane to obtain a first solution, coat the first solution onto a substrate, and dry it to obtain the photopolymer holographic recording medium.

[0173] 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.

[0174] Furthermore, this application provides a volume holographic recording grating, the raw material of which includes the photopolymer type holographic recording medium described in any of the above embodiments.

[0175] 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.

[0176] For example, the photopolymer holographic recording medium proposed in this application has a sensitivity greater than 100 cm / mJ, a recording grating diffraction efficiency greater than 95%, and an exposure amount less than 20 mJ / cm. 2 It possesses excellent properties. Therefore, the volume holographic recording grating made from it also has the advantages of the photopolymer holographic recording medium of this application. Specifically, a sensitivity greater than 100 cm / mJ indicates that only extremely low exposure energy is required to form a stable grating, which can shorten the exposure time, reduce laser power requirements, increase recording speed, and reduce energy consumption efficiency, making it suitable for dynamic recording and low-power devices. A diffraction efficiency greater than 95% indicates that almost all incident light energy is diffracted to the target direction by the grating, thereby reducing light energy loss and making the image clearer, with an exposure amount below 20 mJ / cm. 2 This demonstrates that only a small amount of light energy is needed to complete the curing and photopolymerization process of the photopolymer holographic recording medium, avoiding overheating and deformation caused by high-energy exposure. Furthermore, the large refractive index difference between the high and low refractive index of the dithiocarbamate monomer and the film-forming resin further improves the refractive index modulation of the holographic recording medium, thereby enhancing the diffraction capability of the grating and contributing to a wider field of view.

[0177] 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 .

[0178] 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, optical waveguides and holographic lenses.

[0179] 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 thus has optical performance such as fast recording speed and clear imaging.

[0180] 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.

[0181] 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.

[0182] The optical monomer, the preparation method of the optical monomer, and the photopolymer holographic recording medium containing the optical monomer are described below with reference to specific embodiments.

[0183] Example 1

[0184] Synthesis of optical monomer G3-1

[0185]

[0186] Compound M1-1 (20 mmol) and p-toluenesulfonic acid (20 mmol) were dissolved in ethyl acetate (20 mL) and the mixture was heated to 50 °C. Compound M2-1 (10 mmol) was dissolved in ethyl acetate (10 mL) and slowly added dropwise to the mixed solution of compound M1-1 and p-toluenesulfonic acid. The mixture was stirred for 0.5–36 h. After the reaction was completed, sufficient triethylamine was added to quench the reaction, and the organic phase was extracted three times. The organic phase was dried with anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. Compound P1-1 was obtained by column chromatography.

[0187]

[0188] Under ice bath conditions, compound P1-1 (10 mmol) was dissolved in tetrahydrofuran (20 mL), and sodium hydride (12 mmol) was slowly added. The reaction was stirred for 0.5–10 h, followed by dropwise addition of 3-bromo-1-propene (15 mmol). Stirring continued for another 0.5–10 h after the addition was complete. After the reaction was complete, dilute hydrochloric acid was slowly added dropwise to quench the reaction. Excess solvent was removed by rotary evaporation, and the optical monomer G3-1 of this application was obtained by column chromatography with a yield of 96%.

[0189] The characterization data are as follows:

[0190] 1 H NMR (600MHz, CDCl3) δ7.36–7.29(m,4H),7.25(t,J=1.3Hz,2H),7.21(t,J=7.4Hz,1H ),7.18–7.08(m,3H),6.98(q,J=1.4Hz,1H),6.86(dt,J=7.5,1.5Hz,1H),6.03(ddt, J=16.4,10.1,6.2Hz,1H),5.61(t,J=1.0Hz,1H),5.36(ddt,J=16.7,2.2,0.9Hz,1H) ,5.29(ddt,J=10.1,2.2,1.0Hz,1H),4.50(dt,J=6.2,1.0Hz,2H),2.49–2.26(m,6H).

[0191] 13 C NMR (151MHz, CDCl3) δ159.87,142.87,137.94,133.18,132.94,130.37,129 .64,129.28,127.69,123.90,117.98,114.48,113.02,69.84,59.58,21.23.

[0192] Example 2

[0193] Synthesis of optical monomer G1-1

[0194]

[0195] Compound M1-2 (20 mmol) and naphthalenesulfonic acid (15 mmol) were dissolved in toluene (20 mL) and heated to 50 °C. Compound M2-2 (12 mmol) was dissolved in toluene (10 mL) and slowly added dropwise to the mixed solution of compound M1-2 and naphthalenesulfonic acid. The reaction was stirred for 0.5–36 h. After the reaction was completed, sufficient triethylamine was added to quench the reaction, and the organic phase was extracted three times. The organic phase was dried with anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. Compound P1-2 was obtained by column chromatography.

[0196]

[0197] Under ice bath conditions, compound P1-2 (10 mmol) and triethylamine (20 mmol) were dissolved in dichloromethane (20 mL). After stirring for 10 min, acryloyl chloride (30 mmol) was added dropwise to the mixed solution of compound P1-2 and triethylamine at 0 °C. After the reaction was complete, 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 excess solvent was removed by rotary evaporation. The optical monomer G1-1 of this application was obtained by column chromatography with a yield of 96%.

[0198] The characterization data are as follows:

[0199] 1 H NMR (600MHz, CDCl3) δ7.42–7.35(m,6H),7.25–7.19(m,4H),7.16–7.11(m,2H),6.14– 6.02(m,1H),5.84(s,1H),5.81(d,J=0.9Hz,1H),5.73(t,J=1.0Hz,1H),2.49(s,6H).

[0200] 13 C NMR (151MHz, CDCl3) δ165.16,136.26,135.72,132.80,131.92,129.18,128.56,128.28,127.67,121.20,59.62,15.45.

[0201] Example 3

[0202] Synthesis of optical monomer G4-1

[0203]

[0204] Compound M1-3 (20 mmol) and naphthalenesulfonic acid (15 mmol) were dissolved in toluene (20 mL) and heated to 50 °C. Compound M2-1 (12 mmol) was dissolved in toluene (10 mL) and slowly added dropwise to the mixed solution of compound M1-3 and naphthalenesulfonic acid. The reaction was stirred for 0.5–36 h. After the reaction was completed, sufficient triethylamine was added to quench the reaction, and the organic phase was extracted three times. The organic phase was dried with anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. Compound P1-3 was obtained by column chromatography.

[0205]

[0206] Under ice bath conditions, compound P1-3 (10 mmol) was dissolved in tetrahydrofuran (20 mL), and sodium hydride (12 mmol) was slowly added. The reaction was stirred for 0.5–10 h, followed by dropwise addition of 3-bromo-1-propyne (15 mmol). Stirring continued for another 0.5–10 h after the addition was complete. After the reaction was complete, dilute hydrochloric acid was slowly added dropwise to quench the reaction. Excess solvent was removed by rotary evaporation, and the optical monomer G4-1 of this application was obtained by column chromatography with a yield of 97%.

[0207] The characterization data are as follows:

[0208] 1 H NMR (600MHz, CDCl3) δ7.54(dd,J=7.5,1.5Hz,2H),7.38(td,J=7.5,1.6Hz,2H),7.32(dd,J=7.5,1.6Hz,2H),7.29–7.21(m,2 H),7.14(td,J=7.5,1.6Hz,2H),7.02(p,J=1.0Hz,1H),5.71(t,J=0.9Hz,1H),4.77(d,J=2.9Hz,2H),3.56(t,J=3.0Hz,1H).

[0209] 13 C NMR (151MHz, CDCl3) δ159.30,141.74,134.86,133.17,130.74,129.68,128 .16,127.95,123.96,123.26,115.77,113.65,79.02,75.96,56.64,56.34.

[0210] Example 4

[0211] Synthesis of optical monomer G2-1

[0212]

[0213] Compound M1-4 (20 mmol) and trifluoroacetic acid (20 mmol) were dissolved in ethyl acetate (20 mL) and the mixture was heated to 80 °C. Compound M2-2 (10 mmol) was dissolved in ethyl acetate (10 mL) and slowly added dropwise to the mixed solution of compound M1-4 and trifluoroacetic acid. The reaction was stirred for 0.5–36 h. After the reaction was completed, sufficient triethylamine was added to quench the reaction, and the organic phase was extracted three times. The organic phase was dried with anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. Compound P1-4 was obtained by column chromatography.

[0214]

[0215] Under ice bath conditions, compound P1-4 (10 mmol) was dissolved in dichloromethane (10 mL), and potassium tert-butoxide (10 mmol) was slowly added. After stirring for 0.5–10 h, compound M4-1 (15 mmol) was added dropwise to the reaction system. After the addition was complete, the reaction was continued for another 0.5–10 h. After the reaction was complete, dilute hydrochloric acid was slowly added dropwise to quench the reaction, and excess solvent was removed by rotary evaporation. Compound P2-1 was obtained by column chromatography.

[0216]

[0217] Under ice bath conditions, compound P2-1 (10 mmol) and N,N-diisopropylethylamine (20 mmol) were dissolved in dichloromethane (20 mL). After stirring for 10 min, methacryloyl chloride (30 mmol) was added dropwise to the mixed solution of compound P2-1 and N,N-diisopropylethylamine at 0 °C. After the reaction was complete, dilute hydrochloric acid was added dropwise 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 excess solvent was removed by rotary evaporation. The optical monomer G2-1 of this application was obtained by column chromatography with a yield of 95%.

[0218] The characterization data are as follows:

[0219] 1 H NMR (600MHz, CDCl3) δ7.47–7.38(m,4H),7.37–7.24(m,8H),6.91–6.82(m,2H),5.94(dq,J=2.0,1.0Hz,1H),5.68(t,J=1 .0Hz,1H),5.62(dq,J=2.0,1.0Hz,1H),4.31(td,J=6.9,0.8Hz,2H),4.19(td,J=7.1,0.8Hz,2H),1.95(t,J=1.0Hz,3H).

[0220] 13 C NMR (151MHz, CDCl3) δ167.10,135.94,135.78,134.52,129.41,129.27,128.31,127.61,125.96,115.30,66.23,65.07,59.62,18.23.

[0221] Example 5

[0222] Synthesis of optical monomer G5-1

[0223]

[0224] Compound M1-5 (20 mmol) and tetrafluoroboric acid (20 mmol) were dissolved in acetonitrile (20 mL) and the mixture was heated to 25 °C. Compound M2-2 (10 mmol) was dissolved in acetonitrile (10 mL) and slowly added dropwise to the mixed solution of compound M1-5 and tetrafluoroboric acid. The reaction was stirred for 0.5–36 h. After the reaction was completed, sufficient triethylamine was added to quench the reaction, and the organic phase was extracted three times. The organic phase was dried with anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. Compound P1-5 was obtained by column chromatography.

[0225]

[0226] Under ice bath conditions, compound P1-5 (10 mmol) was dissolved in toluene (10 mL), and sodium methoxide (10 mmol) was slowly added. After stirring for 0.5–10 h, compound M4-2 (15 mmol) was added dropwise to the reaction system. After the addition was complete, the reaction was continued for another 0.5–10 h. After the reaction was complete, dilute hydrochloric acid was slowly added dropwise to quench the reaction. Excess solvent was removed by rotary evaporation, and compound P2-2 was obtained by column chromatography.

[0227]

[0228] Under ice bath conditions, compound P2-2 (10 mmol) was dissolved in tetrahydrofuran (20 mL), and sodium hydride (12 mmol) was slowly added. The reaction was stirred for 0.5–10 h, followed by dropwise addition of 3-bromo-1-propene (15 mmol). Stirring continued for another 0.5–10 h after the addition was complete. After the reaction was complete, dilute hydrochloric acid was slowly added dropwise to quench the reaction. Excess solvent was removed by rotary evaporation, and the optical monomer G5-1 of this application was obtained by column chromatography with a yield of 96%.

[0229] The characterization data are as follows:

[0230] 1 H NMR (600MHz, CDCl3) δ7.65–7.57(m,4H),7.49–7.35(m,14H),7.35–7.30(m,2H) ,6.96–6.77(m,2H),5.73(t,J=1.0Hz,1H),5.20(dt,J=13.4,1.0Hz,2H),4.03(t ,J=7.1Hz,2H),3.97(dt,J=6.2,1.0Hz,2H),3.40(t,J=7.1Hz,2H),1.76(p,J=7. 1Hz,2H),1.59(p,J=7.1Hz,2H),1.48–1.35(m,2H),1.26(pd,J=7.1,0.9Hz,2H).

[0231] 13C NMR (151MHz, CDCl3) δ140.16,139.33,134.70,134.41,128.93,128.55,128.09,127.92,1 26.99,126.75,117.12,114.52,71.29,70.53,68.45,65.73,30.50,30.02,27.52,26.20.

[0232] Example 6

[0233] Synthesis of optical monomer G6-1

[0234]

[0235] Compound M1-2 (20 mmol) and phosphoric acid (20 mmol) were dissolved in dimethyl sulfoxide (20 mL) and heated to 50 °C. Compound M2-1 (10 mmol) was dissolved in dimethyl sulfoxide (10 mL) and slowly added dropwise to the mixed solution of compound M1-2 and phosphoric acid. The reaction was stirred for 0.5–36 h. After the reaction was completed, sufficient triethylamine was added to quench the reaction, and the organic phase was extracted three times. The organic phase was dried with anhydrous sodium sulfate, and excess solvent was removed by rotary evaporation. Compound P1-6 was obtained by column chromatography.

[0236]

[0237] Under ice bath conditions, compound P1-6 (10 mmol) was dissolved in 1,4-dioxane (10 mL), and sodium hydride (10 mmol) was slowly added. After stirring for 0.5–10 h, compound M4-3 (15 mmol) was added dropwise to the reaction system. After the addition was complete, the reaction was continued for another 0.5–10 h. After the reaction was complete, dilute hydrochloric acid was slowly added dropwise to quench the reaction, excess solvent was removed by rotary evaporation, and compound P2-3 was obtained by column chromatography.

[0238]

[0239] Under ice bath conditions, compound P2-3 (10 mmol) was dissolved in tetrahydrofuran (20 mL), and sodium hydride (12 mmol) was slowly added. The reaction was stirred for 0.5–10 h, followed by dropwise addition of 3-bromo-1-propyne (15 mmol). Stirring continued for another 0.5–10 h after the addition was complete. After the reaction was complete, dilute hydrochloric acid was slowly added dropwise to quench the reaction. Excess solvent was removed by rotary evaporation, and the optical monomer G6-1 of this application was obtained by column chromatography with a yield of 98%.

[0240] The characterization data are as follows:

[0241] 1H NMR (600MHz, CDCl3) δ7.41–7.33(m,4H),7.28–7.19(m,5H),7.14–7.06(m,1H),7.02 –6.95(m,1H),6.89(dt,J=7.5,1.6Hz,1H),5.57(d,J=1.0Hz,1H),4.15(d,J=2.9Hz,2 H),4.04(t,J=7.1Hz,2H),3.48(t,J=7.1Hz,2H),2.48(s,6H),2.45(t,J=3.0Hz,1H), 1.75(p,J=7.1Hz,2H),1.60(p,J=7.1Hz,2H),1.51–1.37(m,2H),1.31–1.19(m,10H).

[0242] 13 C NMR (151MHz, CDCl3) δ159.47,141.65,135.63,132.85,129.69,129.18,128.24,1 21.72,115.37,113.31,79.56,75.53,71.88,68.67,59.45,29.77,26.51,15.41.

[0243] Example 7

[0244] Photopolymer-type holographic recording media 7-1 to 7-6 were prepared using the optical monomers described in Examples 1-6. 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 with a humidity of 10%–85% and a temperature of 20°C–50°C to obtain the photopolymer-type holographic recording media (hereinafter referred to as holographic recording media). The specific components of photopolymer-type holographic recording media 7-1 to 7-6 are shown in Tables 1 to 7.

[0245] Table 1

[0246]

[0247]

[0248] Table 2

[0249]

[0250]

[0251] Table 3

[0252]

[0253] Table 4

[0254]

[0255]

[0256] Table 5

[0257]

[0258] Table 6

[0259]

[0260]

[0261] Comparative Example 1

[0262] The composition is roughly the same as that of the photopolymer holographic recording medium 7-1 in Example 7. The difference is that the optical monomer G3-1 is not added in the comparative example, but 40 wt% of N-vinylpyrrole is added to obtain the ordinary photopolymer holographic recording medium 1.

[0263] Comparative Example 2

[0264] The composition is roughly the same as that of the photopolymer holographic recording medium 7-2 in Example 7. The difference is that the optical monomer G1-1 is not added in the comparative example, but 40 wt% of N-vinylindole is added to obtain the ordinary photopolymer holographic recording medium 2.

[0265] Comparative Example 3

[0266] The composition is roughly the same as that of the photopolymer holographic recording medium 7-4 in Example 7. The difference is that the optical monomer G2-1 is not added in the comparative example, but 53 wt% of 2-phenoxyethyl methacrylate is added to obtain the ordinary photopolymer holographic recording medium 3.

[0267] Comparative Example 4

[0268] The composition is roughly the same as that of the photopolymer holographic recording medium 7-6 in Example 7. The difference is that the optical monomer G6-1 is not added in the comparative example, but 18 wt% of benzyl acrylate is added to obtain the ordinary photopolymer holographic recording medium 4.

[0269] Test case

[0270] (1) The refractive index of the optical monomers synthesized in Examples 1 to 6 was tested, and the results are shown in Table 7.

[0271] (2) The performance of the photopolymer holographic recording media 7-1 to 7-6 containing optical monomers in Example 7 and the ordinary photopolymer holographic recording media of the comparative example were tested, and the results are shown in Table 8.

[0272] During testing, the various holographic recording media in Example 7 can be exposed to lasers of different wavelengths depending on the photosensitive system, with an exposure intensity of 3 mW / cm². 2 .

[0273] 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).

[0274]

[0275] 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.

[0276] Table 7 Refractive indices of the monomers synthesized in Examples 1-6

[0277] Example monomer Refractive index Example 1 G3 1.67 Example 2 G1 1.69 Example 3 G4 1.74 Example 4 G2 1.65 Example 5 G5 1.67 Example 6 G6 1.66

[0278] Table 8. Holographic performance parameters of the holographic recording media of Example 7 and the comparative example.

[0279]

[0280] As shown in Table 7, the refractive index of the optical monomers prepared in the embodiments of this application is 1.65 to 1.74. Therefore, the optical monomers provided by this application have a high refractive index, which can further enhance the refractive index difference between the writing monomer and the film-forming resin, thereby improving the refractive index modulation of the holographic recording medium to generate a stronger grating structure and increase the grating storage density.

[0281] Specifically, as shown in Table 8, the diffraction efficiency of the holographic recording medium containing the optical monomer of this application prepared in Example 7 is 95.31% to 98.77%, that is, the diffraction efficiency of the holographic recording medium provided by this application is greater than 95%. High diffraction efficiency means high light energy utilization and low light energy loss. In other words, almost all the incident light energy is diffracted to the target direction by the grating, which greatly improves the brightness and clarity of the holographic display. Furthermore, the exposure of the holographic recording medium containing the optical monomer of this application is 4.90 mJ / cm².2 ~9.73mJ / cm 2 The sensitivity is 100.34 cm / mJ to 201.39 cm / mJ, which is much greater than that of the ordinary holographic recording media prepared in Comparative Examples 1-4 (whose exposure is 70.21 mJ / cm). 2 ~92.31mJ / cm 2 The sensitivity is 6.34 cm / mJ to 7.88 cm / mJ. Therefore, the holographic recording medium provided in this application also has a sensitivity greater than 100 cm / mJ and an exposure amount less than 20 mJ / cm. 2 The advantages include higher sensitivity, larger interference pattern area that can be recorded per unit energy (millijoules), shorter hologram writing time, faster data transmission speed, and lower exposure, which means that only a small amount of light energy is needed to complete curing and photopolymerization, avoiding overheating and deformation of materials caused by high-energy exposure.

[0282] Furthermore, such as Figure 1 As shown, holographic recording media 7-1, 7-3, and 7-5 containing the optical monomers of this application achieve a superior diffraction efficiency of greater than 95% with relatively small exposure amounts, while from... Figure 2 It can be seen that the ordinary holographic recording media prepared in Comparative Examples 1 and 3 require relatively high exposure levels to achieve a diffraction efficiency of approximately 40%, and combined with... Figure 1 and Figure 2 As shown, comparing holographic recording medium 7-1 with Comparative Example 1 and holographic recording medium 7-4 with Comparative Example 3, it can be seen that the holographic recording medium containing the optical monomer of this application has a higher diffraction efficiency and requires a lower exposure.

[0283] 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. An optical monomer characterized by, Any one of the following structural general formulae: wherein R1represents a methyl group or hydrogen, R2represents a hydrogen or a substituent on a benzene ring, the substituent being selected from the group consisting of a phenyl group, halogen, C1-C4alkyl, A1represents C1-C4alkyl, and n is a positive integer, n = 0-9.

2. The optical monomer of claim 1, wherein, The optical monomer is a compound with the following structural formula:

3. A method of producing an optical monomer as claimed in claim 1, characterized in that, Comprising: Compound M1 is dissolved in an organic solvent with an acid reagent, after the first processing operation, compound M2 is added to react, to obtain compound P1; wherein the first processing operation comprises at least a heating operation and a stirring operation, and the compound M1 is selected from compounds of the general structure R2represents hydrogen or a substituent on the phenyl ring, the substituent being selected from halogen, C1-C4alkyl, A1represents C1-C4alkyl; The compound M2 is selected from the group consisting of compounds of the following general structure: The structural general formula of the compound P1 is as follows:

4. The method of claim 3, wherein the optical monomer is prepared by the steps of: The optical monomer has a structural general formula G1, comprising the following steps: The compound P1 is dissolved in an organic solvent with an acid binding agent, and compound M3 is added to react, to obtain the optical monomer G1; wherein the compound M3 is acryloyl chloride or methacryloyl chloride; Alternatively, the optical monomer has any one of the structural general formulae G3 or G4, comprising the following steps: The compound P1 is dissolved in a first solvent, after the second processing operation, a deprotonating agent is added, after a period of time, compound M5 is added, to obtain the optical monomer with the structural general formula G3 or G4; wherein the second processing operation at least includes a cooling operation and a stirring operation, and the compound M5 is 3-bromo-1-propene or 3-bromo-1-propyne.

5. The method for preparing an optical monomer according to claim 3, characterized in that, The optical monomer has any one of the structural general formulae G2, G5 or G6, and further comprising the following steps: The compound P1 is dissolved in a first solvent, after the second processing operation, a deprotonating agent is added, after a period of time, compound M4 is added, to obtain compound P2; The second processing operation at least includes a cooling operation and a stirring operation, and the compound M4 has a general structural formula of: The compound P2 has a general structural formula of: n is a positive integer, and n=0-9.

6. The method for preparing an optical monomer according to claim 5, characterized in that, The optical monomer has the structural general formula G2, and further comprising the following steps: The compound P2 is dissolved in an organic solvent with an acid binding agent, and compound M3 is added to react, to obtain the optical monomer G2; wherein the compound M3 is acryloyl chloride or methacryloyl chloride; Alternatively, the optical monomer has any one of the structural general formulae G5 or G6, comprising the following steps: The compound P2 is dissolved in a first solvent, after the second processing operation, a deprotonating agent is added, after a period of time, compound M5 is added, to obtain the optical monomer with the structural general formula G5 or G6; wherein the second processing operation at least includes a cooling operation and a stirring operation, and the compound M5 is 3-bromo-1-propene or 3-bromo-1-propyne.

7. The preparation method according to claim 3, characterized in that, The organic solvent is selected from one or more of methanol, ethanol, petroleum ether, dichloromethane, trichloromethane, ethyl acetate, tetrahydrofuran, acetonitrile, benzene, toluene, N,N-dimethylformamide, dimethyl sulfoxide, dimethoxyethane and 1,4-dioxane; And / or, the acid reagent is selected from one or more of p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, camphorsulfonic acid, naphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, sulfosalicylic acid, citric acid, acetic acid, formic acid, phosphoric acid, anhydrous hydrogen peroxide, tetrafluoroboric acid, trifluoroacetic acid, pentafluoroacetic acid, heptafluoropropionic acid and phosphoric acid; And / or, the molar ratio of the compound M1, the acid reagent and the compound M2 is 2:(1-2):

1.

8. The production method according to claim 4 or 6, characterized by, The acid binding agent is selected from one or more of triethylamine, pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, tetrabutylammonium bromide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium acetate, sodium hydroxide, potassium hydroxide, calcium oxide and potassium tert-butoxide; and / or, the first solvent is selected from one or more of petroleum ether, dichloromethane, trichloromethane, ethyl acetate, tetrahydrofuran, acetonitrile, benzene, toluene, N,N-dimethylformamide, dimethyl sulfoxide, dimethoxyethane and 1,4-dioxane; and / or, the deprotonating agent is selected from one or more of n-butyllithium, t-butyllithium, phenyllithium, sodium hydride, potassium hydride, sodium amide, potassium amide, sodium bis(trimethylsilyl)amide, lithium diisopropylamide, potassium hydroxide, sodium hydroxide, sodium methoxide, sodium tert-butoxide, potassium tert-butoxide, triethylamine, 1,5-diazabicyclo[4.3.0]non-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, tetramethylsilane triflate, potassium phosphate, potassium carbonate, sodium carbonate and sodium bicarbonate.

9. A photopolymer type holographic recording medium, characterized by, The raw material thereof comprises the following components a) to h); the component a) is a compound having multiple isocyanate-reactive functional groups; the component b) is a polyisocyanate-based compound; the component c) is an optical monomer; the component d) is a polymerizable monomer; the component e) is a photosensitive initiation system; the component f) is a chain transfer agent; the component g) is an optional catalyst; the component h) is an optional additive. The optical monomer is at least one of the optical monomers G1 to G6 of claim 1.

10. The photopolymer type holographic recording medium according to claim 9, wherein, The composition and content of the photopolymer type holographic recording medium are as follows: the component a) is a compound having multiple isocyanate-reactive functional groups 10wt% to 50wt%; the component b) is a polyisocyanate-based compound 10wt% to 50wt%; the component c) is an optical monomer 1wt% to 30wt%; the component d) is a polymerizable monomer 10wt% to 40wt%; the component e) is a photosensitive initiation system 0.1wt% to 3wt%; the component f) is a chain transfer agent 0.1wt% to 3wt%; the component g) is a catalyst 0.1wt% to 5wt%; the component h) is an additive 0.1wt% to 10wt%.

11. The photopolymer type holographic recording medium according to claim 9, wherein, The content of the optical monomer in the entire photopolymer type holographic recording medium is 0.1wt% to 30wt%; and / or, the isocyanate-reactive functional group is a hydroxyl group, and the molar ratio of the hydroxyl group in the component a) to the isocyanate functional group in the component b) is 1:

1.

12. The photopolymer type holographic recording medium according to claim 9, wherein The isocyanate-reactive functional group is a hydroxyl group; the compound having multiple isocyanate-reactive functional groups includes a compound with a refractive index less than or equal to a first refractive index threshold and two or more hydroxyl functional groups, and the first refractive index threshold is any value between 1.5 and 1.55; and / or, the polyisocyanate-based compound includes a compound with a refractive index less than or equal to a second refractive index threshold and 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 alkenyl naphthalene compound, alkenyl anthracene compound, alkenyl benzene compound, acrylic compound, methacrylic compound, acrylate compound, methacrylate compound, N-vinyl pyrrole, N-vinyl carbazole, N-vinyl imidazole, N-vinyl indole, N-vinyl pyrrolidone, and trans-N-3-alkynyl butenyl carbazole; And / or, the photosensitive initiator system comprises a photosensitizer and a photoinitiator; And / or, the chain transfer agent is a thiol compound; And / or, the catalyst is a tertiary amine catalyst and an organometallic catalyst; And / or, the additive comprises at least one of defoaming agent, leveling agent, plasticizer, and water removal agent.

13. The photopolymer type holographic recording medium according to claim 12, characterized by The compound having multiple isocyanate reactive functional groups comprises at least one of tetraethylene glycol, trimethylol ethane, glycerol, triethanolamine, polyester polyol with a molecular weight of 200-2000, polycarbonate polyol, and polyether polyol; And / or, the polyisocyanate-based compound comprises at least one of hexamethylene diisocyanate, trimethyl hexamethylene diisocyanate, (2,4,6-trioxotriazine-1,3,5(2H,4H,6H)-triyl)tris(hexamethylene) isocyanate, butane-1,4-diisocyanate, isophorone diisocyanate, and dicyclohexyl methane diisocyanate; And / or, the chain transfer agent comprises at least one of dodecyl mercaptan, mercaptoethanol, hexanethiol, phenylethyl mercaptan, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, and 4-methyl-4H-1,2,4-triazole-3-thiol; And / or, the catalyst comprises at least one of triethylenediamine, bis(dimethylaminoethyl) ether, dimethyl ethanolamine, 2-(2-dimethylamino-ethoxy) ethanol, trimethylhydroxyethylpropylenediamine, N,N-bis(dimethylaminopropyl) isopropanolamine, dibutyl tin dilaurate, stannous octoate, potassium carboxylate catalyst, and bismuth carboxylate catalyst.

14. The photopolymer type holographic recording medium according to claim 12, wherein, The photosensitizer comprises at least one of cyanine dye, fluorescein dye, coumarin ketone dye, nitrogen-containing aromatic heterocyclic compound, aromatic amine compound, and benzylidene cycloalkanone compound; The photoinitiator comprises at least one of aromatic ketone compound, benzoin and its derivatives, benzil ketals, acyl phosphine oxide, aryl borate ammonium, chromium salt, aryl diazonium salt, onium salt, organometallic compound, or these compounds; The mass ratio of the photosensitizer and the photoinitiator is (0.001-1):(0.1-3).

15. The photopolymer type holographic recording medium according to claim 12, wherein, The defoaming agent is a silicone defoaming agent and / or a non-silicone polymeric defoaming agent, and the content of the defoaming agent in the photopolymerizable holographic recording medium is less than or equal to 3wt%; And / or, the leveling agent is a silicone surface additive, and the content of the leveling agent in the photopolymerizable holographic recording medium is less than or equal to 3wt%. and / or, the plasticizer is selected from at least one of toluene, xylene, dimethylformamide, dimethylacetamide, glycerol, phthalate ester, and the content of the plasticizer in the photopolymer type holographic recording medium is less than or equal to 3wt%; and / or, the water scavenger includes at least one of p-toluenesulfonyl isocyanate, triethyl orthoformate, and the content of the water scavenger in the photopolymer type holographic recording medium is less than or equal to 3wt%.

16. A method for preparing the photopolymer type holographic recording medium according to any one of claims 9-15, wherein, weighing the compound having a plurality of isocyanate-reactive functional groups, the polyisocyanate-based compound, the optical monomer, the polymerizable monomer, the photoinitiating system, the chain transfer agent, the catalyst, and the additive in a container, and stirring sufficiently to dissolve to form a mixture solution; filtering the mixture solution using a filter membrane to obtain a first solution; coating the first solution on a substrate, and obtaining the photopolymer type holographic recording medium after drying.

17. The method of claim 16, wherein, The drying is performed in a dark room with humidity of 10% to 85% and temperature of 20°C to 50°C.

18. A volume holographic recording grating, characterized by The raw material includes the photopolymer type holographic recording medium according to any one of claims 9-15.

19. A holographic optical element, characterized by The raw material includes the photopolymer type holographic recording medium according to any one of claims 9-15.

20. An optical device, characterized by The holographic optical element includes the holographic optical element according to claim 19. The holographic optical element includes the holographic optical element according to claim 19.

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