Optical monomer, preparation method thereof, resin mixture and application

Abstract

The invention discloses an optical monomer and a preparation method thereof, a resin mixture and application, the optical monomer takes benzodithiophene as a core structure, thioether bonds and tetravinyl groups are introduced, a rigid framework is provided for the optical monomer through the benzodithiophene, the rigidity of a polymer molecular chain is reduced through the thioether bonds, and the optical monomer has a good optical property. The crosslinking density of the optical monomer is increased through tetravinyl groups, so that the obtained optical monomer not only has high refractive index and strong light transmission, but also has good heat resistance.

Description

Technical Field

[0001] This application relates to the field of optical materials technology, and in particular to optical monomers and their preparation methods, resin mixtures and their applications. Background Technology

[0002] With the rapid development of optical communication, precision optics and consumer electronics industries, optical devices are iterating towards high performance, miniaturization, lightweight and durability. This also puts forward more stringent standards for the performance requirements of optical resin materials, such as increasing the refractive index to reduce lens thickness or increase light-gathering ability, and having good heat resistance to ensure dimensional stability and reliability during processing and use. However, existing optical resin materials (such as polymethyl methacrylate PMMA, polycarbonate PC, etc.) are difficult to have both high refractive index and long-term weather resistance and heat resistance. Summary of the Invention

[0003] This application provides an optical monomer, a resin mixture, a preparation method, and an application, aiming to solve the problem that existing optical resin materials are difficult to achieve both high refractive index and long-term weather resistance and heat resistance.

[0004] Firstly, this application provides an optical monomer with the following chemical structural formula: .

[0005] As can be seen from the above technical solutions, the optical monomer proposed in the first aspect of this application uses benzodithiophene as its core skeleton and introduces thioether bonds and tetravinyl groups. Benzodithiophene provides the material basis for the rigidity and symmetry of the molecular structure. The introduced thioether bonds, due to the high bond energy of the CS bond and the large atomic radius and polarizability of the sulfur atom, combined with the conjugation effect of the benzene ring, not only give the optical monomer a high refractive index but also significantly improve the high-temperature resistance of the optical monomer and the optical resin material made from it. It should be noted that the thioether structure itself has good thermal stability and can also reduce the rigidity of the polymer molecular chain, slightly increasing the chain segment mobility, which helps to absorb some thermal stress and reduce thermal degradation. Therefore, this optical monomer has good heat resistance. Furthermore, the introduction of tetravinyl groups increases the crosslinking density of the optical monomer and restricts the movement of the network molecular chains, which not only enhances the adhesion between the optical resin material and the substrate but also further increases the glass transition temperature of the optical resin material.

[0006] It should also be noted that the benzodithiophene skeleton, thioether bond and tetravinyl group present in the optical monomer of this application form a synergistic enhancement effect, which enables the optical monomer to have high refractive index, good heat resistance and strong adhesion, breaking through the limitation of single performance optimization.

[0007] Secondly, this application provides a method for preparing the aforementioned optical monomer, comprising: Under an inert environment, p-bromotrimethylsilthiophene, bis(tributyltin) sulfide, a catalyst, and an organic solvent are reacted to obtain the first intermediate; After dissolving the first intermediate in an organic solvent and performing a first treatment operation, a deprotonating agent is added to obtain a first mixture, and sulfur chloride is added to the first mixture to react and obtain a second intermediate. After dissolving the second intermediate in an organic solvent and performing the first treatment operation, a deprotonating agent is added to obtain a second mixture. Dibromodifluoromethane is then added to the second mixture to react and obtain a third intermediate. In an inert environment, the third intermediate and thiourea are dissolved in a protic solvent and reacted to obtain a third mixture. The third mixture is then hydrolyzed under alkaline conditions to obtain a fourth intermediate. Under an inert environment, the fourth intermediate, epichlorohydrin, and an alkaline reagent are dissolved in water and reacted to obtain the fifth intermediate; At 0 °C, the fifth intermediate was dissolved in an organic solvent and thionyl chloride was added to react and obtain the sixth intermediate; In an inert environment, the sixth intermediate and thiourea are dissolved in a protic solvent and reacted to obtain a fourth mixture, which is then hydrolyzed under alkaline conditions to obtain a seventh intermediate. In an inert environment, the seventh intermediate and the base reagent are dissolved in a protic solvent, and ethylene bromide is added to react and obtain the optical monomer; wherein the first processing operation includes at least a cooling operation and a stirring operation.

[0008] As can be seen from the above technical solutions, the preparation method of the aforementioned optical monomer proposed in the second aspect of this application uses conventional chemical raw materials and successfully prepares the aforementioned optical monomer through a multi-step substitution reaction, and the preparation method is simple.

[0009] Thirdly, this application provides a resin mixture comprising: First solvent; Photoinitiator; Leveling agent; And the aforementioned optical components.

[0010] The resin mixture proposed in the third aspect of this application has a high refractive index, good light transmittance, and excellent heat resistance.

[0011] Fourthly, this application proposes the application of the aforementioned resin mixture for nanoimprinting.

[0012] The application of the resin mixture proposed in the fourth aspect of this application has the advantages of high refractive index, strong light transmittance and excellent heat resistance when the resin mixture is applied to nanoimprinting. Attached Figure Description

[0013] Figure 1 This diagram illustrates the fabrication route of the optical monomer provided in an embodiment of this application. Detailed Implementation

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] With the rapid development of optical communication, precision optics and consumer electronics industries, optical devices (such as camera lenses, VR / AR lenses, optical fibers, display panels, optical films, etc.) are iteratively developing towards high performance, miniaturization, lightweighting and durability, which puts forward increasingly higher requirements for optical resin materials. For example, they need to increase the refractive index to reduce the lens thickness or increase the light-gathering ability, and have good heat resistance to ensure dimensional stability and reliability during processing and use. However, existing optical resin materials (such as polymethyl methacrylate PMMA, polycarbonate PC, etc.) are difficult to have both high refractive index and long-term weather resistance and heat resistance.

[0020] Based on this, this application provides an optical device, the chemical structure of which is shown below: .

[0021] In this embodiment, the optical monomer uses benzodithiophene as its core framework, and also incorporates thioether bonds and tetravinyl groups. Benzodithiophene provides the material basis for the rigidity and symmetry of the molecular structure. The introduced thioether bonds, due to their high CS bond energy and the large atomic radius and polarizability of sulfur atoms, combined with the conjugation effect of the benzene ring, not only give the optical monomer a high refractive index but also significantly improve the high-temperature resistance of the optical monomer and the optical resin material made from it. It should be noted that the thioether structure itself has good thermal stability and can also reduce the rigidity of the polymer molecular chain, slightly increasing the chain segment mobility, which helps absorb some thermal stress and reduce thermal degradation. Therefore, this optical monomer has good heat resistance. Furthermore, the introduction of tetravinyl groups increases the crosslinking density of the optical monomer, restricting the movement of the network molecular chains. This not only enhances the adhesion between the optical resin material and the substrate but also further increases the glass transition temperature of the optical resin material.

[0022] It should also be noted that the benzodithiophene skeleton, thioether bond and tetravinyl group present in the optical monomer of this application form a synergistic enhancement effect, which makes the optical monomer have a high refractive index (refractive index as high as 1.785), good heat resistance and strong adhesion, breaking through the limitation of single performance optimization.

[0023] like Figure 1 As shown in the embodiments of this application, a method for preparing the aforementioned monomer is also provided, including the following steps: Step S1: Under an inert environment, p-bromotrimethylsilthiophene, bis(tributyltin) sulfide, a catalyst, and an organic solvent are provided to react and obtain the first intermediate.

[0024] It is understandable that step S1 constructs a CS bond through a Stille coupling reaction and generates a trimethylsilyl-substituted bisthiophene sulfide compound (i.e., the first intermediate A).

[0025] Organic solvents are used to dissolve the reaction substrate and promote the reaction process. Organic solvents include, but are not limited to, one or more of petroleum ether, dichloromethane, chloroform, ethyl acetate, tetrahydrofuran, acetonitrile, benzene, toluene, N,N-dimethylformamide, dimethyl sulfoxide, dimethoxyethane, diethyl ether, and 1,4-dioxane. It should be noted that the above solvents are only examples, and the solvents that can be used in this application are not limited to these.

[0026] The catalyst includes at least one or more palladium catalysts selected from tetraphenylphosphine palladium (Pd(PPh3)4), tris(dibenzylacetone)palladium (Pd2(dba)2), di(tri-tert-butylphosphine)palladium, and tricyclohexylphosphine palladium, etc. These palladium catalysts are merely illustrative examples, and the palladium catalysts that can be used in this application are not limited to these. In some specific examples, the addition of ligands such as triphenylphosphine or tert-butylphosphine when using tetraphenylphosphine palladium (Pd(PPh3)4) can enhance catalytic activity and promote the reaction process.

[0027] It should also be noted that step S1 is typically performed in an inert, anhydrous, and oxygen-free environment to prevent deactivation of the palladium catalyst. An inert environment may be achieved using an inert gas, including but not limited to nitrogen and argon.

[0028] In some examples, the reaction temperature of step S1 is 80~120°C. More specifically, the reaction is most effective when the reaction temperature of step S1 is the reflux temperature, i.e., the reaction temperature is slightly higher than the boiling point of the solvent used. For example, when toluene is used as the solvent, the reaction temperature of step S1 can be set to, for example, 115°C.

[0029] Step S2: After dissolving the first intermediate in an organic solvent and performing the first treatment operation, a deprotonating agent is added to obtain a first mixture. Sulfur chloride is then added to the first mixture to react and obtain the second intermediate. The first treatment operation includes at least a cooling operation and a stirring operation.

[0030] In step S2, a hydrogen at position 2 on the thiophene ring is extracted by a deprotonating agent, thereby activating the first intermediate A into carbanion intermediate I. Subsequently, carbanion intermediate I is used to construct a benzodithiophene skeleton (i.e., the second intermediate) through sulfur chloride. Therefore, the first mixture includes at least carbanion intermediate I.

[0031] It should be noted that the first processing operation includes 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 this.

[0032] It is understood that deprotonating agents include, but are not limited to, organometallic bases, metal amino compounds, metal alkoxides and metal hydrides, inorganic bases and organic bases.

[0033] 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.

[0034] 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.

[0035] 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 0.5 h to 10 h. 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.

[0036] It should also be noted that the deprotonating agent should be added to the reaction system in batches and slowly to avoid violent reaction that could cause damage to the sprayed material and personnel.

[0037] Step S3: After dissolving the second intermediate in an organic solvent and performing the first treatment operation, a deprotonating agent is added to obtain a second mixture. Dibromodifluoromethane is then added to the second mixture to react and obtain a third intermediate.

[0038] It is understood that step S3 involves removing the trimethylsilyl (TMS) substituent from the second intermediate B using a deprotonating agent, followed by bromine substitution with dibromodifluoromethane (CF2Br)2 to obtain the third intermediate C. The second mixture includes at least the carbanion intermediate II formed from the second intermediate B. The reaction mechanism and reaction conditions of step S3 are the same as those of step S3, the only difference being the reaction substrate. Therefore, the specific details are as described in step S3 and will not be repeated here.

[0039] Step S4: Under inert conditions, the third intermediate and thiourea are dissolved in a protic solvent and reacted to obtain a third mixture. The third mixture is then hydrolyzed under alkaline conditions to obtain a fourth intermediate.

[0040] It should be noted that since thiol groups are oxidized in air, the reaction needs to be carried out in an inert environment. The same applies below, and this application will not repeat it. It can be understood that in step S4, the third intermediate C and thiourea undergo a substitution reaction in a protic solvent, and the generated isothiourea salt I (i.e., the third mixture) is hydrolyzed under alkaline conditions to generate a thiol compound (i.e., the fourth intermediate D).

[0041] Alkaline conditions, such as aqueous solutions of sodium hydroxide or potassium hydroxide, are not limited to this application. For example, a thiol compound (i.e., the fourth intermediate D) can be obtained by stirring a 20% aqueous solution of sodium hydroxide in the third mixture obtained after the reaction for a period of time.

[0042] Proton solvents include, but are not limited to, one or more of ethanol, methanol, ethylene glycol, isopropanol, formic acid, acetic acid, water, or ethanolamine, etc., and are not limited in this application.

[0043] Step S5: Under an inert environment, the fourth intermediate, epichlorohydrin, and alkaline reagent are dissolved in water to react and obtain the fifth intermediate.

[0044] In step S5, the mercapto compound (i.e., the fourth intermediate D) undergoes an epoxide addition ring-opening reaction with epichlorohydrin in the presence of a base reagent and water to yield the fifth intermediate E. In some examples, step S5, with stirring for 16 hours at room temperature, yields the fifth intermediate E. Basic reagents help activate thiol compounds (i.e., the fourth intermediate D) to enhance their nucleophilicity and promote the reaction process. Examples of basic reagents include, but are not limited to, one or more of borax, sodium hydroxide, potassium tert-butoxide, potassium hydroxide, sodium methoxide, alumina-supported base, or triethylamine.

[0045] In step S6, at 0°C, the fifth intermediate is dissolved in an organic solvent and thionyl chloride is added to react and obtain the sixth intermediate.

[0046] In step S6, thionyl chloride is used as the chlorinating agent to convert the alcohol hydroxyl group in the fifth intermediate E into a chlorine group, yielding the sixth intermediate F. Since this reaction is exothermic, it needs to be carried out at a low temperature, such as an ice-salt bath or ice bath (0 °C). Simultaneously, thionyl chloride needs to be added slowly to the reaction system to avoid increased side reactions due to localized high temperatures and the risk of material spillage. Specifically, in some examples, dichloromethane is used as the reaction solvent in step S6, and after the thionyl chloride is added, the reaction is refluxed at 40 °C for 2–4 h, resulting in better reaction performance.

[0047] Step S7: Under inert conditions, the sixth intermediate and thiourea are dissolved in a protic solvent and reacted to obtain a fourth mixture. The fourth mixture is then hydrolyzed under alkaline conditions to obtain a seventh intermediate.

[0048] It should be noted that in step S7, the sixth intermediate F is reacted with thiourea to yield the seventh intermediate G. The reaction conditions and principles are the same as in step S4, the only difference being the reaction substrate. For details, please refer to step S4, which will not be repeated here. That is, the fourth mixture is isothiourea salt II formed from the sixth intermediate F.

[0049] Step S8: Under an inert environment, the seventh intermediate and the base reagent are dissolved in a protic solvent, and ethylene bromide is added to react and obtain an optical monomer.

[0050] In step S8, the seventh intermediate G is activated by a base reagent to form a thiolate anion, which then undergoes nucleophilic substitution with ethylene bromide to yield an allyl sulfide compound (i.e., an optical monomer). In some specific examples, in step S8, the seventh intermediate G is reacted with ethylene bromide at 40 °C for 12 hours to obtain the optical monomer of this application.

[0051] In this embodiment, the chemical raw materials used to prepare the optical monomer are readily available and can be successfully prepared through a series of simple and mature substitution reactions, making the preparation method simple.

[0052] This application also provides a resin mixture comprising a first solvent, a photoinitiator, a leveling agent, and the aforementioned optical monomers.

[0053] The first solvent includes propylene glycol methyl ether acetate, ethyl acetate, dichloromethane, ethanol, isopropanol, butyl acetate, tetrahydrofuran, dimethyl sulfoxide, N,N One or more of dimethylformamide, tetramethylethylenediamine, and carbon tetrachloride.

[0054] Photoinitiators include one or more of thioxanthone, thioxanthone derivatives, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxyl chloride, diethoxyacetophenone, 4-tert-butyltrichloroacetophenone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide. In some specific examples, the absorption wavelength of the photoinitiator is 368 nm-420 nm. Therefore, the photoinitiator can initiate the polymerization reaction under light irradiation without affecting the overall light transmittance of the optical resin material.

[0055] Leveling agents include one or more of BYK331, BYK370, BYK3505, and BYK348. Specifically, BYK331, BYK370, BYK3505, and BYK348 are leveling agents manufactured by BYK GmbH in Germany. The BYK series of leveling agents have excellent leveling properties.

[0056] In some specific examples, the resin mixture comprises the following components by weight percentage: The first solvent is 9 wt% - 63 wt%. Photoinitiator 0.1 wt% - 3 wt%; Leveling agent 0.1 wt% - 5 wt%; Optical monomers: 30 wt% - 90 wt%.

[0057] In this embodiment, using a first solvent at a weight percentage of 9 wt% to 63 wt% ensures uniform mixing of the components. Below this range, the components will not mix evenly and their compatibility will decrease; above this range, the effective component will be insufficient. Using a photoinitiator at a weight percentage of 0.1 wt% to 3 wt% initiates the polymerization reaction under light irradiation. Below this range, fewer free radicals are generated under light irradiation, resulting in slower curing or even ineffective curing; above this range, the curing process is faster, and the reaction is difficult to control. Using a leveling agent at a weight percentage of 0.1 wt% to 5 wt% helps the resin mixture spread uniformly on the substrate, reducing bubbles and surface defects. Below this range, the resin mixture's spreading is hindered; above this range, costs are high and spreading is too rapid. Using an optical monomer at a weight percentage of 30 wt% to 90 wt% gives the cured resin mixture high refractive index, high light transmittance, and thermal stability. Below this range, the cured resin mixture will have insufficient refractive index and increased material consumption; above this range, film formation will be hindered.

[0058] Therefore, this application uses the aforementioned optical monomers with high refractive index to prepare resin mixtures. The prepared resin mixtures have high refractive index, good light transmittance, strong thermal stability, are easy to coat, can be quickly cured after light exposure, and can be nanoimprinted after curing.

[0059] Specifically, the preparation method of the resin material involves, for example, mixing the components of a resin mixture and placing it in a mold or coating it onto a substrate, then carrying out a polymerization / curing reaction under appropriate temperature, light, or catalyst conditions to ultimately form a transparent solid polymer film. The specific process parameters (temperature, time, light intensity, atmosphere, etc.) are optimized based on the reactivity of the optical monomers and the selected polymerization method.

[0060] For example, the weight percentage of the first solvent can be, for example, 9 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, and 63 wt%, etc.; the weight percentage of the photoinitiator can be, for example, 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, and 3 wt%, etc.; the weight percentage of the leveling agent can be, for example, 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, and 5 wt%, etc.; and the weight percentage of the optical monomer can be, for example, 30 wt%, 35 wt%, 40 wt%, 45 wt%, etc. wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt% and 90 wt%, etc.

[0061] For example, the resin mixture may include the following components in weight percentages: 30 wt% first solvent, 0.1 wt% photoinitiator, 0.1 wt% leveling agent, and 69.8 wt% optical monomer.

[0062] For example, the resin mixture may include the following components in weight percentages: 9 wt% first solvent, 0.1 wt% photoinitiator, 0.9 wt% leveling agent, and 90 wt% optical monomer.

[0063] For example, the resin mixture may include the following components in weight percentages: 30 wt% first solvent, 3 wt% photoinitiator, 5 wt% leveling agent, and 62 wt% optical monomer.

[0064] For example, the resin mixture may include the following components in weight percentages: 63 wt% first solvent, 2 wt% photoinitiator, 5 wt% leveling agent, and 30 wt% optical monomer.

[0065] For example, the resin mixture may include the following components in weight percentages: 47 wt% first solvent, 1 wt% photoinitiator, 2 wt% leveling agent, and 50 wt% optical monomer.

[0066] For example, the resin mixture may include the following components in weight percentages: 57 wt% first solvent, 0.5 wt% photoinitiator, 4.5 wt% leveling agent, and 38 wt% optical monomer.

[0067] Specifically, the resin mixture has a refractive index greater than 1.785, which is high and facilitates nanoimprinting.

[0068] This application also proposes the application of resin mixtures. When the resin mixtures in the foregoing embodiments are coated onto a substrate and cured, a resin material can be obtained. This resin material can be used for nanoimprinting, and when the resin material is applied to nanoimprinting, it has the characteristics of good shape retention and high light transmittance.

[0069] The optical monomers, their preparation methods, resin mixtures, and applications of this application are described below with reference to reaction formulas and specific embodiments.

[0070] Example 1: Preparation of optical monomers:

[0071] Under nitrogen protection, bis(tributyltin) sulfide (Bu3Sn)2S (20.9 g, 0.5 equivalent) and tetrakis(triphenylphosphine)palladium (3.95 g, 0.05 equivalent) were added to dry toluene (15 ml) to form a mixture. Then, p-bromotrimethylsilthiophene (16.1 g, 68.4 mmol) was added, and the reaction mixture was refluxed at 111 °C for 17 hours. After the reaction was completed, the reaction solution was quenched with KF aqueous solution, and the organic phase was extracted with diethyl ether. After washing with water and drying with MgSO4 to remove the solvent, the first intermediate A (9.88 g, 28.8 mmol, yield 64%) was obtained by column chromatography (using hexane as eluent) to obtain a colorless oily intermediate A. 1 H NMR (500MHz, CDCl3): δ 0.29 (s, 18H, TMS), 7.11 (d, 2H), 7.35 (d, 2H).

[0072]

[0073] Under nitrogen protection at -78 °C, the first intermediate A (9.3 g, 24 mmol) was dissolved in dry diethyl ether (50 ml). Thiol (3.18 mmol, 33.4 ml, 2.2 equivalents) was added dropwise to the reaction system, and the mixture was stirred for 1 hour. Then, sulfur chloride (SCl2, 2.74 g, 1.1 equivalents) was added, and the mixture was stirred at room temperature for 4 hours. After the reaction was complete, the reaction solution was quenched with water, acidified with hydrochloric acid solution, and the organic phase was extracted with diethyl ether. The obtained organic phase was washed with water, dried over anhydrous magnesium sulfate to remove the solvent, and purified by column chromatography (using hexane as eluent) to give the second intermediate B (8.54 g, 22.82 mmol, 78% yield), a yellow oil. 1 H NMR (500 MHz, CDCl3): δ 0.27 (18H, s, TMS), 6.92 (2H, m, ArH).

[0074] Under nitrogen protection at -78 °C, the second intermediate B (8.4 g, 36.8 mmol) was dissolved in dry tetrahydrofuran (100 ml). Butyllithium (79.5 mmol, 50 ml, 2.2 equivalents) was added dropwise to the reaction system, and the mixture was stirred for 0.5 hours. Then, dibromodifluoromethane (9.5 ml, 2.2 equivalents) was added, and the mixture was stirred at room temperature for 0.5 hours. After the reaction was complete, the reaction solution was quenched with water, acidified with hydrochloric acid solution, and the organic phase was extracted with diethyl ether. The obtained organic phase was washed with water and dried over magnesium sulfate. After removing the solvent, the mixture was purified by column chromatography (using hexane as eluent) to give the third intermediate C (5.04 g, 22.12 mmol, 61% yield) as a pale yellow solid. 1 H NMR (500 MHz, CDCl3): δ 6.89 (2H, s, ArH).

[0075]

[0076] Under nitrogen protection, the third intermediate C (5 g, 22.01 mmol) was dissolved in dry ethanol (100 ml), and a thiourea ethanol solution (5.01 g, 66.03 mmol, 1.5 equivalents) was added dropwise. After the addition was complete, the reaction mixture was stirred at 70 °C for 12 hours. After the reaction was complete, a 20% sodium hydroxide aqueous solution (3.52 g, 2.2 equivalents) was added to the reaction system, and the mixture was stirred at room temperature for 0.5 hours. The reaction solution was acidified with hydrochloric acid aqueous solution, and the organic phase was extracted with ethyl acetate. The obtained organic phase was washed with water and dried over magnesium sulfate. After removing the solvent, the mixture was purified by column chromatography (using hexane / ethyl acetate = 2:1 v / v as eluent) to give the fourth intermediate D (4.36 g, 14.93 mmol, 90% yield) as a pale yellow solid. 1 H NMR (500 MHz, CDCl3): δ6.89 (2H, d, ArH), 1.34 (2H, s, SH).

[0077]

[0078] Under nitrogen protection, epichlorohydrin (5.49 g, 59.72 mmol) and borax (2.27 g, 5.972 mmol, 0.1 equivalent) were added to deionized water (135 ml), followed by the addition of fourth intermediate D (4.36 g, 14.93 mmol). The reaction mixture was then stirred at room temperature for 16 hours. After the reaction was complete, the organic phase was extracted with dichloromethane (3 times, 100 ml each time). The combined organic phases were washed with water (approximately 100 ml, twice) and then with saturated brine to obtain a crude product of 43.0 g (93%) of a yellow viscous liquid (i.e., fifth intermediate E, with a theoretical yield of 6.47 g, 13.59 mmol). The crude product was used directly in the next reaction without further purification. 1 H NMR (500 MHz, CDCl3): δ 6.53 (2H, d, ArH), 4.76 (2H, m, OH), 3.78 (4H, d, CH2), 4.09 (2H, t, CH), 3.27 (4H, m, CH2).

[0079]

[0080] Under ice-salt bath conditions (0 °C), the fifth intermediate E (6.47 g, 13.59 mmol) was dissolved in dichloromethane (30 mL) in a dry three-necked flask. Thionyl chloride (4.0 mL, 54.2 mmol) was then slowly added dropwise to the reaction system using a constant-pressure dropping funnel (approximately 10–15 min). After the addition was complete, the reaction system was slowly heated to 40 °C and refluxed for 2–4 h. The reaction progress was monitored by TLC (developing solvent: PE:EA = 5:1). After the reaction was complete, the reaction was stopped and cooled to room temperature. The crude product was washed 2–3 times with a mixed solvent (n-hexane / ethyl acetate = 1:1), filtered, and dried under vacuum to obtain a yellow viscous liquid, the sixth intermediate F (6.73 g, 13.12 mmol). 1 H NMR (500 MHz, CDCl3): δ 6.53 (2H, d, ArH), 3.78 (4H, s, CH2), 4.09 (2H, s, CH), 3.27 (4H, s, CH2).

[0081]

[0082] Under nitrogen protection, the sixth intermediate F (6.73 g, 13.12 mmol) was dissolved in dry ethanol (100 ml), and a thiourea ethanol solution (7.97 g, 104.96 mmol, 2 equivalents) was added dropwise. After the addition was complete, the reaction mixture was stirred at 70 °C for 12 hours. After the reaction was complete, a 20% sodium hydroxide aqueous solution (4.62 g, 2.2 equivalents) was added to the reaction system, and the mixture was stirred at room temperature for 0.5 hours. The reaction mixture was acidified with hydrochloric acid aqueous solution, and the organic phase was extracted with ethyl acetate. The obtained organic phase was washed with water and dried over magnesium sulfate. After removing the solvent, the mixture was purified by column chromatography (using hexane / ethyl acetate = 1:1 v / v as eluent) to give the seventh intermediate G (5.66 g, 11.23 mmol, 87% yield) as a yellow liquid. 1 H NMR (500 MHz, CDCl3): δ 6.53 (2H, d, ArH), 3.78 (4H, t, CH2), 4.09 (2H, d, CH), 3.27 (4H, m, CH2), 1.44 (8H, m, SH).

[0083]

[0084] Under nitrogen protection, the seventh intermediate G (5.66 g, 11.23 mmol) was diluted with anhydrous ethanol (69 ml) and sodium hydroxide (2.69 g, 67.38 mmol) was added. After stirring at room temperature for 10 minutes, ethylene bromide (7.28 g, 67.38 mmol) was slowly added to the reaction system, and the mixture was heated to 40 °C and stirred for 12 hours. After the reaction was complete, the reaction solution was cooled to room temperature, and hydrochloric acid (13.5 g, 36%) was added to form a precipitate. The precipitate was filtered and concentrated under reduced pressure to obtain a slightly yellow, viscous liquid optical monomer (6.08 g, 10.01 mmol). 1 H NMR (500 MHz, CDCl3): δ 6.53 (2H,d, ArH), 6.46 (8H, m, CH), 4.97 (4H, m, CH), 3.78 (4H, t, CH2), 4.09 (2H, m,CH), 3.27 (4H, d, CH2).

[0085] Preparation of Resin Mixture 1: The above-mentioned yellow viscous liquid optical monomer (6g), dichloromethane (3g), photoinitiator diethoxyacetophenone (0.06g), and BYK370 (0.05g) were added to a 50mL volumetric flask. The mixture was vigorously mixed for 2 hours under light-protected conditions, and then filtered through a 0.45µm syringe filter to obtain Resin Mixture 1. Resin Mixture 1 was homogenized on a 4-inch resin wafer (3500rpm, 60s), followed by grating imprinting to form a nanoimprint adhesive. Refractive index, transmittance, and grating structure were measured using SEM, and the parameters of the grating structure were also measured.

[0086] Comparative Example 1: Bisphenol fluorene-modified acrylate (6g), dichloromethane (3g), photoinitiator diethoxyacetophenone (0.06g), and BYK370 (0.05g), purchased through commercial channels, were vigorously mixed for 2 hours under light-protected conditions. The mixture was then filtered through a 0.45µm syringe filter to obtain a resin mixture. The resin mixture was homogenized on a 4-inch resin wafer (3500 rpm, 60s), followed by grating imprinting to form a nanoimprint adhesive. Refractive index, transmittance, and grating structure were measured using SEM, and the parameters of the grating structure were also tested.

[0087] Comparative Example 2: 9,9-bis(4-allyloxyphenyl)fluorene (6g), dichloromethane (3g), photoinitiator diethoxyacetophenone (0.06g), and BYK370 (0.05g), purchased commercially, were vigorously mixed for 2 hours under light-protected conditions. The mixture was then filtered through a 0.45µm syringe filter to obtain a resin mixture. The resin mixture was homogenized on a 4-inch resin wafer (3500 rpm, 60 s), followed by grating imprinting to form a nanoimprint adhesive. Refractive index, transmittance, and grating structure were measured using SEM, and the parameters of the grating structure were also tested.

[0088] Experimental example: The performance parameters of the cured films prepared in Example 1, Comparative Example 1, and Comparative Example 2 were tested, including measurements of refractive index, transmittance, SEM testing of the grating structure, and testing of the parameters of the grating structure. The results are shown in Table 1.

[0089] The cured films obtained in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to the following tests: (1) Refractive index: Tested using an ellipsometer (ME-L Muller matrix spectral ellipsometer, Yiguang Technology).

[0090] (2) Light transmittance: High-precision haze meter (HM-150 Murakami Color MCRL).

[0091] (3) Grating parameter testing: Micro-nano structures were measured using SEM (SU5000 Hitachi).

[0092] (4) Membrane thickness: The membrane thickness was measured using a SEM (SU5000 Hitachi).

[0093] Table 1. Comparison of test performance of cured films after grating imprinting of resin mixtures from Examples 1, 1, and 2.

[0094] It should be noted that, as shown in Table 1, the structural parameters of Example 1, Comparative Example 1, and Comparative Example 2 are similar in terms of film thickness, grating height, grating width, and grating period. Therefore, differences in refractive index, transmittance, and glass transition temperature due to structural differences can be eliminated. In other words, the differences in refractive index, transmittance, and glass transition temperature are mainly due to the structural properties of the optical monomer.

[0095] Furthermore, as shown in Table 1, the sulfur-containing optical monomers prepared in this application exhibit significant advantages in optical performance and microstructure reproducibility. Specifically, the refractive index of the optical resin material prepared from the optical monomers of this application is 1.78, exceeding the industry high-end threshold (n>1.75), and compared with Comparative Example 1 and Comparative Example 2, its refractive index increases by 9.8%~13.0%.

[0096] It is understandable that the higher the refractive index, the more significant the phase abrupt change of light at the material interface, the stronger the modulation effect of the grating on the incident light, and the lower the energy loss. Moreover, the optical resin material made from the optical monomer of this application has a transmittance of 86% in the visible light region (400-800nm), and the high transmittance can ensure that the optical element made has good light efficiency.

[0097] Furthermore, the glass transition temperature (Tg) of the optical resin material made from the optical monomer of this application is 125°C, which breaks through the limit of thermoplastic resin materials (usually Tg < 110°C). This means that the optical resin material made from the optical monomer of this application can work stably for a long time at 100°C. In other words, the optical monomer provided by this application meets the extreme requirements of materials for scenarios such as AR diffractive waveguides, ultra-thin mobile phone lenses, and high-temperature laser lenses.

[0098] In summary, the resin material formed by curing the resin mixture containing the optical monomers of this application has high refractive index, high transmittance, and good heat resistance.

[0099] 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 unit, characterized in that, The chemical structural formula of the optical monomer is as follows: 。 2. A method for preparing an optical monomer as described in claim 1, characterized in that, include: Under an inert environment, p-bromotrimethylsilthiophene, bis(tributyltin) sulfide, a catalyst, and an organic solvent are reacted to obtain the first intermediate; After dissolving the first intermediate in an organic solvent and performing a first treatment operation, a deprotonating agent is added to obtain a first mixture, and sulfur chloride is added to the first mixture to react and obtain a second intermediate. After dissolving the second intermediate in an organic solvent and performing the first treatment operation, a deprotonating agent is added to obtain a second mixture. Dibromodifluoromethane is then added to the second mixture to react and obtain a third intermediate. In an inert environment, the third intermediate and thiourea are dissolved in a protic solvent and reacted to obtain a third mixture. The third mixture is then hydrolyzed under alkaline conditions to obtain a fourth intermediate. Under an inert environment, the fourth intermediate, epichlorohydrin, and an alkaline reagent are dissolved in water and reacted to obtain the fifth intermediate; At 0 °C, the fifth intermediate was dissolved in an organic solvent and thionyl chloride was added to react and obtain the sixth intermediate; In an inert environment, the sixth intermediate and thiourea are dissolved in a protic solvent and reacted to obtain a fourth mixture, which is then hydrolyzed under alkaline conditions to obtain a seventh intermediate. In an inert environment, the seventh intermediate and the base reagent are dissolved in a protic solvent, and ethylene bromide is added to react and obtain the optical monomer. The first processing operation includes at least a cooling operation and a stirring operation.

3. The preparation method according to claim 2, characterized in that, The catalyst is selected from one or more of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4), tris(dibenzylideneacetone)palladium (Pd2(dba)2), di(tri-tert-butylphosphine)palladium, and tricyclohexylphosphinepalladium; And / or, the organic solvent is selected from one or more of petroleum ether, dichloromethane, chloroform, ethyl acetate, tetrahydrofuran, acetonitrile, benzene, toluene, N,N-dimethylformamide, dimethyl sulfoxide, dimethoxyethane, diethyl ether, and 1,4-dioxane; And / or, the deprotonating agent is selected from at least one of n-butyllithium, tert-butyllithium, phenyllithium, sodium hydride, potassium hydride, sodium amino, potassium amino, sodium bis(trimethylsilyl)amino, diisopropylaminolithium, 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, tetramethylsilyltrifluoromethanesulfonate, potassium phosphate, potassium carbonate, and sodium carbonate.

4. The preparation method according to claim 2, characterized in that, The alkaline reagent is selected from one or more of borax, sodium hydroxide, potassium tert-butoxide, potassium hydroxide, sodium methoxide, alumina-supported alkali, or triethylamine; And / or, the protonated solvent is selected from one or more of acetonitrile, ethanol, methanol, ethylene glycol, isopropanol, formic acid, acetic acid, water, or ethanolamine.

5. A resin mixture, characterized in that, include First solvent; Photoinitiator; Leveling agent; The optical unit is the optical unit as described in claim 1.

6. The resin mixture according to claim 5, characterized in that, The resin mixture comprises the following components by weight percentage: The first solvent is 9 wt% - 63 wt%. Photoinitiator 0.1 wt% - 3 wt%; Leveling agent 0.1 wt% - 5 wt%; Optical monomers: 30 wt% - 90 wt%.

7. The resin mixture according to claim 5, characterized in that, The first solvent is selected from propylene glycol methyl ether acetate, ethyl acetate, dichloromethane, ethanol, isopropanol, butyl acetate, tetrahydrofuran, dimethyl sulfoxide, N,N One or more of dimethylformamide, tetramethylethylenediamine, and carbon tetrachloride; And / or, the photoinitiator is selected from one or more of thioxanthone, thioxanthone derivatives, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxyl chloride, diethoxyacetophenone, 4-tert-butyltrichloroacetophenone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; And / or, the leveling agent is selected from one or more of BYK331, BYK370, BYK3505 and BYK348.

8. The resin mixture according to claim 7, characterized in that, The photoinitiator has an absorption wavelength of 368 nm. 420 nm.

9. The resin mixture according to any one of claims 5-8, characterized in that, The resin mixture has a refractive index of 1.785 and a glass transition temperature of 125°C.

10. An application of the resin mixture according to any one of claims 5-9, characterized in that, The resin mixture is used for nanoimprinting.

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