Sulfur-containing optical monomer as well as preparation method and application thereof

Abstract

The invention provides a sulfur-containing optical monomer and a preparation method and application thereof.The sulfur-containing optical monomer has the structure shown in the formula I. The sulfur-containing optical monomer achieves brand-new hybridization of sulfur atoms and organic groups, and has the advantages of being high in sulfur content, good in stability and the like. The refractive index (nD) of a polymer film obtained after photopolymerization curing of the sulfur-containing optical monomer exceeds 1.7, and the sulfur-containing optical monomer has high refractive index, can be used for optical devices, and lays a key foundation for preparation of high-performance optical equipment.

Description

Technical Field

[0001] This application belongs to the field of optical monomers, and relates to a sulfur-containing optical monomer, its preparation method and application. Background Technology

[0002] In the rapid development of modern optical devices (such as high-reflectivity gratings and VR lenses), the research and development of high refractive index (RI) materials has become crucial. In particular, the performance of grating devices (such as reflection bandwidth and anti-dispersion capability) is highly dependent on the RI and dispersion characteristics of the material. High refractive index difference gratings (such as silicon-based gratings) achieve broadband high reflectivity by enhancing the localization effect of the light field, but the processing difficulty and brittleness of inorganic materials limit their application. Organic sulfur-containing materials, due to their tunable molecular structure, can optimize the balance between RI and Abbe number through sulfur content and molecular configuration (such as cis double bond arrangement). Therefore, academia and industry are turning to sulfur-containing organic polymer materials. Furthermore, focusing on simplifying and improving the efficiency of sulfur atom introduction methods has become a crucial research direction and technological breakthrough. This "simplification" aims to overcome the pain points of traditional sulfur-containing monomer synthesis, such as high cost, cumbersome steps, high energy consumption, or environmental safety hazards. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the purpose of this application is to provide a sulfur-containing optical monomer, its preparation method, and its applications. The sulfur-containing optical monomer of this application possesses a high refractive index, resulting in a polymer with high refractive index and transmittance after curing, as well as being environmentally friendly, having a simplified process, low cost, and high material stability.

[0004] To achieve this objective, the following technical solution is adopted in this application:

[0005] On the one hand, this application provides a sulfur-containing optical monomer, which has the structure shown in Formula I:

[0006] ;

[0007] Where R is selected from , , , , , , , , , or The wavy line represents the connection site of the functional group.

[0008] In this application, the sulfur-containing optical monomer is any one of the following compounds 1-9:

[0009] .

[0010] On the other hand, this application provides a method for preparing the sulfur-containing optical monomer as described above, the method comprising the following steps:

[0011] (1) The dithiol-terminated monomer shown in Formula II reacts with carbon disulfide under alkaline conditions;

[0012] ;

[0013] (2) Add allyl bromide to the reaction solution of step (1) to react and obtain the sulfur-containing optical monomer shown in formula I.

[0014] In this application, the reactions described in steps (1) and (2) are carried out under alkaline conditions provided by an alkaline substance selected from any one or at least two of the following: sodium hydroxide, potassium hydroxide, potassium tert-butoxide, potassium carbonate, or cesium carbonate.

[0015] In this application, a high-sulfur monomer is prepared using a xanthation reaction. The dithiol-terminated monomer contains two thiol groups. Under alkaline conditions, the two sulfide groups (-SH) of the dithiol-terminated monomer are deprotonated, generating a dithiol anion ⁻SRS⁻. In an alkaline aqueous solution, the dithiol anion (⁻SRS⁻) generated from the dithiol-terminated monomer attacks a carbon disulfide molecule, which is essentially a reaction leading to the formation of a dithiocarboxylic acid. The most crucial intermediate is the dithiocarbonate anion (also commonly called xanthate), where S=S⁻ is attached to the sulfur atom of the -SRS- chain. This can be understood as one of the deprotonated sulfur atoms acting as a nucleophile to attack CS2, generating a structure similar to ⁻S2C-SRS-CS2⁻. Allyl bromide acts as an electrophile. At room temperature, the two negatively charged centers (dithiocarboxylate C(=S)S⁻) of the strong nucleophile (the bis-anionic intermediate formed in the previous step) are attacked by two allyl bromide molecules, resulting in a dialkylation reaction. Therefore, the final product has an allyl (CH₂=CH-CH₂-) substituent attached to each end group.

[0016] The reaction pathway can be summarized as follows:

[0017]

[0018] .

[0019] In this application, the molar ratio of the dithiol-terminated monomer shown in Formula II to carbon disulfide is 1:2 to 1:4, for example, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4.

[0020] In this application, the molar ratio of the dithiol-terminated monomer shown in Formula II to allyl bromide is 1:2 to 1:3, for example, 1:2, 1:2.5 or 1:3.

[0021] In this application, the reaction in step (1) is carried out in the presence of a phase transfer catalyst (PTC). The phase transfer catalyst is selected from any one or a combination of at least two of tetrabutylammonium sulfate, hexadecyltrimethylammonium chloride, 18-crown-6, 15-crown-5, or open-chain polyethylene glycol.

[0022] In this application, the molar ratio of the phase transfer catalyst to the dithiol-terminated monomer shown in Formula II is 5:1-20:1, for example 5:1, 8:1, 10:1, 12:1, 15:1, 18:1 or 20:1. The amount of phase transfer catalyst used in this application is relatively large, which helps to transfer the anions in the aqueous phase to the organic phase (or interface) to react with the electrophilic reagent.

[0023] In this application, the solvent for the reaction in step (1) is any one or a combination of at least two of the following: water, methanol, acetonitrile, tetrahydrofuran, n-hexane, n-heptane, or ethanol.

[0024] In this application, the temperature of the reaction in step (1) is room temperature (15-30°C), and the reaction time is 0.5-3h, for example 0.5h, 1h, 1.5h, 2h, 2.5h or 3h.

[0025] In this application, the temperature of the reaction in step (2) is room temperature (15-30°C), and the reaction time is 0.5-3h, for example 0.5h, 1h, 1.5h, 2h, 2.5h or 3h.

[0026] On the other hand, this application provides a polymer film obtained by polymerizing the sulfur-containing optical monomers as described above.

[0027] In this application, the polymer film is obtained by photopolymerization of the sulfur-containing optical monomers as described above under the action of an initiator.

[0028] In this application, the photocuring is performed under LED light irradiation, wherein the LED light wavelength is 365nm and the irradiation energy is 1-30mW / cm². 2 For example, 1 mW / cm 2 3 mW / cm 2 5 mW / cm 2 8 mW / cm 2 10 mW / cm 2 15 mW / cm 2 20 mW / cm 2 25 mW / cm2 28 mW / cm 2 Or 30 mW / cm 2 The irradiation time is 0.5-3 hours, for example, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0029] On the other hand, this application provides the application of the sulfur-containing optical monomer or the polymer film described above in optical devices.

[0030] Compared with the prior art, this application has the following advantages:

[0031] The sulfur-containing optical monomer of this application achieves a novel hybridization of sulfur atoms and organic groups, and has a high sulfur content. The polymer film obtained after photopolymerization and curing of the sulfur-containing optical monomer has a refractive index (nD) of more than 1.7, which is a high refractive index. It can be used in optical devices, laying a key foundation for the preparation of high-performance optical equipment. Detailed Implementation

[0032] The technical solution of this application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely to help understand this application and should not be regarded as specific limitations on this application.

[0033] Example 1

[0034] This embodiment provides a sulfur-containing optical monomer, the structure of which is as follows:

[0035]

[0036] Its preparation method includes the following steps:

[0037] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. Thiophene-2,5-dimercapto (15.688 g, 0.106 mol), 150 mL of deionized water, and sodium hydroxide (12.8 g, 0.32 mol) were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetra-n-butylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, 150 mL of a prepared allyl bromide (38.72 g, 0.32 mol) toluene solution was slowly added dropwise to the above reaction solution using a constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 1) in 49% yield.

[0038] The NMR characterization of monomer 1 is as follows:

[0039] 1 H NMR (DMSO 400 MHz): δ 5.01 (s, 2H), 6.36 (d, 2H), 5.32 (d, 2H), 7.12 (s, 2H).

[0040] Example 2

[0041] In this embodiment, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0042]

[0043] Its preparation method includes the following steps:

[0044] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. 26.5 g (0.106 mol) of 4',4-dimercaptodiphenyl sulfide, 150 mL of deionized water, and 12.8 g (0.32 mol) of sodium hydroxide were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetra-n-butylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, 150 mL of a prepared allyl bromide (38.72 g, 0.32 mol) toluene solution was slowly added dropwise to the above reaction solution using a constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 2) in 52% yield.

[0045] The NMR characterization of monomer 2 is as follows:

[0046] 1 H NMR (DMSO 400 MHz): δ 7.20 (d, 8H), 6.36 (t, 2H), 5.32 (s, 2H), 5.01 (s, 2H).

[0047] Example 3

[0048] In this embodiment, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0049]

[0050] Its preparation method includes the following steps:

[0051] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. 1,4-Dithiane-2,5-dithiol (19.398 g, 0.106 mol), 150 mL of deionized water, and sodium hydroxide (12.8 g, 0.32 mol) were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetrabutylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, 150 mL of a prepared allyl bromide (38.72 g, 0.32 mol) toluene solution was slowly added dropwise to the above reaction solution using a constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 3) in 39% yield.

[0052] The NMR characterization of monomer 3 is as follows:

[0053] 1 H NMR (DMSO 400 MHz): δ 5.10 (s, 2H), 6.36 (s, 2H), 5.32 (d, 2H), 3.56 (m, 4H), 3.85 (m, 2H).

[0054] Example 4

[0055] In this embodiment, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0056]

[0057] Its preparation method includes the following steps:

[0058] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. 1,4-Dithiane-2,5-di(methanethiol) (22.472 g, 0.106 mol), 150 mL of deionized water, and sodium hydroxide (12.8 g, 0.32 mol) were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetra-n-butylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, 150 mL of a prepared allyl bromide (38.72 g, 0.32 mol) toluene solution was slowly added dropwise to the above reaction solution using a constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 4) in 65% yield.

[0059] The NMR characterization of monomer 4 is as follows:

[0060] 1 H NMR (DMSO 400 MHz): δ 5.10 (s, 2H), 6.36 (m, 2H), 5.32 (m, 2H), 2.88 (d, 4H), 3.31 (d, 4H), 3.08 (s, 2H).

[0061] Example 5

[0062] In this embodiment, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0063]

[0064] Its preparation method includes the following steps:

[0065] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic plunger, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. 40.2 g (0.106 mol) of 5,5'-(thiophene-2,5-dimethylbis(sulfonamide))bis(1,3,4-thiadiazole-2-thiol), 150 mL of deionized water, and 12.8 g (0.32 mol) of sodium hydroxide were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetrabutylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, 150 mL of a prepared allyl bromide (38.72 g, 0.32 mol) toluene solution was slowly added dropwise to the above reaction solution using a constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 5) in 43% yield.

[0066] The NMR characterization of monomer 5 is as follows:

[0067] 1 H NMR (DMSO 400 MHz): δ 5.10 (s, 2H), 6.36 (d, 2H), 5.32 (s, 2H), 4.13 (d, 4H), 6.93 (d, 2H).

[0068] Example 6

[0069] In this embodiment, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0070]

[0071] Its preparation method includes the following steps:

[0072] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. 1,1'-thiobis(naphthalene-2-thiol) (37.1 g, 0.106 mol), 150 mL of deionized water, and sodium hydroxide (12.8 g, 0.32 mol) were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetra-n-butylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, 150 mL of a prepared allyl bromide (38.72 g, 0.32 mol) toluene solution was slowly added dropwise to the above reaction solution using a constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 6) in 67% yield.

[0073] The NMR characterization of monomer 6 is as follows:

[0074] 1 H NMR (DMSO 400 MHz): δ 5.10 (s, 2H), 6.36 (t, 2H), 5.32 (s, 2H), 7.40 (s, 2H), 7.43 (s, 2H), 7.48 (t, 4H), 7.95 (m, 2H), 8.09 (s, 2H).

[0075] Example 7

[0076] In this embodiment, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0077]

[0078] Its preparation method includes the following steps:

[0079] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. Dithioethanethiol (16.748 g, 0.106 mol), 150 mL of deionized water, and sodium hydroxide (12.8 g, 0.32 mol) were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetrabutylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, a 150 mL solution of allyl bromide (38.72 g, 0.32 mol) in toluene was slowly added dropwise to the above reaction mixture through the constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 7) in 71% yield.

[0080] The NMR characterization of monomer 7 is as follows:

[0081] 1 H NMR (DMSO 400 MHz): δ 5.10 (s, 2H), 6.36 (t, 2H), 5.32 (t, 2H), 4.14 (d, 4H).

[0082] Example 8

[0083] In this embodiment, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0084]

[0085] Its preparation method includes the following steps:

[0086] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. Trithiodimethyl mercaptan (20.14 g, 0.106 mol), 150 mL of deionized water, and sodium hydroxide (12.8 g, 0.32 mol) were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetrabutylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, a 150 mL solution of allyl bromide (38.72 g, 0.32 mol) in toluene was slowly added dropwise to the above reaction mixture through the constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 8) in 42% yield.

[0087] The NMR characterization of monomer 8 is as follows:

[0088] 1 H NMR (DMSO 400 MHz): δ 5.10 (s, 2H), 6.36 (d, 2H), 5.32 (t, 2H), 4.14 (d, 4H).

[0089] Example 9

[0090] In this embodiment, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0091]

[0092] Its preparation method includes the following steps:

[0093] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. Dimethyl mercaptopentyl sulfide (26.924 g, 0.106 mol), 150 mL of deionized water, and sodium hydroxide (12.8 g, 0.32 mol) were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetrabutylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, a 150 mL solution of allyl bromide (38.72 g, 0.32 mol) in toluene was slowly added dropwise to the above reaction mixture through the constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (monomer 9) in 83% yield.

[0094] The NMR characterization of monomer 9 is as follows:

[0095] 1 H NMR (DMSO 400 MHz): δ 5.10 (s, 2H), 6.36 (d, 2H), 5.32 (s, 2H), 4.14 (m, 4H).

[0096] Comparative Example 1

[0097] In this comparative example, a sulfur-containing optical monomer is provided, the structure of which is as follows:

[0098]

[0099] Its preparation method includes the following steps:

[0100] Nitrogen gas was introduced into a three-necked round-bottom flask equipped with a magnetic stir bar, a constant-pressure dropping funnel, and a thermometer for several minutes to displace the air and create an inert reaction environment. Methanethiol dithiomethane (18.126 g, 0.106 mol), 150 mL of deionized water, and sodium hydroxide (12.8 g, 0.32 mol) were added to the flask, and the reaction mixture was stirred at room temperature. Subsequently, a mixture containing carbon disulfide (24.3 g, 0.32 mol) and tetrabutylammonium sulfate (0.6 g, 1.06 mmol) was slowly added dropwise to the above alkaline solution through the constant-pressure dropping funnel. During this process, the dropping rate was controlled to ensure a mild exothermic reaction and to maintain the system temperature close to room temperature. After the addition was complete, the reaction was stirred continuously at room temperature for 3 hours. Finally, 150 mL of a prepared allyl bromide (38.72 g, 0.32 mol) toluene solution was slowly added dropwise to the above reaction solution using a constant-pressure dropping funnel. After the addition was complete, the reaction mixture was stirred continuously at room temperature for 3 hours until the reaction was complete. The product was extracted, washed with saturated brine, and dried with anhydrous sodium sulfate to obtain the crude product. The crude product was purified by column chromatography to obtain the product (i.e., the comparative compound) in a yield of 42%.

[0101] The NMR characterization of the comparative compounds is as follows: 1 H NMR (DMSO 400 MHz): δ 5.10 (s, 2H), 6.36 (d, 2H), 5.32 (m, 2H), 4.02 (d, 4H), 3.59 (d, 2H).

[0102] The monomers obtained from the above examples and comparative examples were uniformly mixed with photoinitiator (1173) at a mass percentage ratio of 95%:5% to obtain a mixture. The mixture was then homogenized on a 4-inch glass wafer (3500 rpm, 60 s), followed by grating imprinting. Ultraviolet curing (365 nm) under oxygen-free conditions yielded a nanoimprint adhesive. Refractive index, transmittance, and grating structure were measured using SEM, and the parameters of the grating structure were also tested.

[0103] 1. Refractive index test. The refractive index was measured using an ellipsometer. The refractive indices of the imprinting adhesives prepared in Examples 1 to 9 and Comparative Example 1 are shown in Table 1.

[0104] 2. Transmittance Test. A haze meter was used for testing. The transmittance of the imprinting adhesives prepared in Examples 1 to 9 and Comparative Example 1 is shown in Table 1.

[0105] 3. Grating parameter testing: Micro-nano structures were measured using an SEM (SU5000 Hitachi); Film thickness: Film thickness was measured using an SEM (SU5000 Hitachi).

[0106] The test results are shown in Table 1 below.

[0107] Table 1 Properties of polymer films after monomer photopolymerization

[0108]

[0109] As can be seen from the comparison data of Examples 1-9 and Comparative Example 1 in Table 1, the novel sulfur-containing compounds prepared in this application exhibit significant advantages in optical properties and microstructure reproducibility, as detailed below:

[0110] The height (70~90 nm) and width (140~160 nm) of the nanoimprinted patterns in Examples 1-9 are highly consistent with the design values. The key factors are: matching of monomer thermal flowability: sulfur-containing monomers exhibit ideal viscoelastic flowability at imprinting temperature (100~120℃), ensuring complete filling of microcavities; extremely low curing shrinkage: synergistic crosslinking of thioether bonds and acrylate groups reduces curing shrinkage, avoiding microstructure collapse or breakage during demolding;

[0111] Examples 1-9 are all novel compounds. Furthermore, compared to Comparative Example 1, the refractive index (RI) of Examples 1, 3, 5, and 9 is all >1.74 (up to 1.755@589 nm), far exceeding the 1.68 of Comparative Example 1. Moreover, Example 9 exhibits a transmittance of over 90% (400~800 nm wavelength).

[0112] This application's novel sulfur-containing compound, through molecular design, successfully overcomes the bottlenecks of low light transmittance and poor processability of traditional high-RI materials, providing an innovative material solution for high-precision optical devices such as gratings that combines high refractive index, high light transmittance, and excellent structural reproducibility.

[0113] The applicant declares that this application illustrates the sulfur-containing optical monomer, its preparation method, and its application through the above embodiments, but this application is not limited to the above embodiments, that is, it does not mean that this application must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent substitutions of the raw materials of this application's products, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this application.

Claims

1. A sulfur-containing optical monomer, characterized in that, The sulfur-containing optical monomer has the structure shown in Formula I: ； Where R is selected from , , , , , , , , , or The wavy line represents the connection site of the functional group.

2. The sulfur-containing optical monomer according to claim 1, characterized in that, The sulfur-containing optical monomer is any one of the following compounds 1-9: 。 3. The method for preparing sulfur-containing optical monomers according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) The dithiol-terminated monomer shown in Formula II reacts with carbon disulfide under alkaline conditions; ； (2) Add allyl bromide to the reaction solution of step (1) to react and obtain the sulfur-containing optical monomer shown in formula I.

4. The preparation method according to claim 3, characterized in that, The alkaline conditions are provided by an alkaline substance selected from the following: any one or a combination of at least two of sodium hydroxide, potassium hydroxide, potassium tert-butoxide, potassium carbonate, or cesium carbonate; The molar ratio of the dithiol-terminated monomer to carbon disulfide shown in Formula II is 1:2-1:4; The molar ratio of the dithiol-terminated monomer to allyl bromide shown in Formula II is 1:2-1:

3.

5. The preparation method according to claim 3, characterized in that, The reaction in step (1) is carried out in the presence of a phase transfer catalyst selected from any one or a combination of at least two of tetra-n-butylammonium sulfate, hexadecyltrimethylammonium chloride, 18-crown-6, 15-crown-5 or open-chain polyethylene glycol.

6. The preparation method according to claim 5, characterized in that, The molar ratio of the phase transfer catalyst to the dithiol-terminated monomer shown in Formula II is 5:1-20:

1.

7. The preparation method according to claim 3, characterized in that, The solvent for the reaction in step (1) is any one or a combination of at least two of the following: water, methanol, acetonitrile, tetrahydrofuran, n-hexane, n-heptane, or ethanol; The reaction in step (1) is carried out at room temperature for 0.5-3 hours. The reaction in step (2) is carried out at room temperature for 0.5-3 hours.

8. A polymer film, characterized in that, The polymer film is obtained by polymerizing the sulfur-containing optical monomers described in claim 1 or 2.

9. The polymer film according to claim 8, characterized in that, The polymer film is obtained by photopolymerization of the sulfur-containing optical monomer as described in claim 1 or 2 under the action of an initiator; The photocuring is performed under LED light irradiation, wherein the LED light wavelength is 365nm and the irradiation energy is 1-30mW / cm². 2 The irradiation time is 0.5-3 hours.

10. The use of the sulfur-containing optical monomer according to claim 1 or 2 or the polymer film according to claim 8 or 9 in optical devices.

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