A polyphenylsilsesquioxane block liquid silicone rubber and a method for preparing the same

Abstract

The application provides a polyphenylsilsesquioxane block liquid silicone rubber and a preparation method thereof, and relates to the technical field of organic silicon polymer materials.The polyphenylsilsesquioxane block liquid silicone rubber provided by the application has the structural formula as follows: wherein R is independently a hydroxyl group or a formula; a and b are positive integers, and the ratio of a to b is (14:1) to (1:6.5). The polyphenylsilsesquioxane block liquid silicone rubber has good heat resistance, realizes balanced optimization of material performance, and provides a new generation of liquid silicone rubber with reliability and adaptability for high-demand industrial scenes.

Description

Technical Field

[0001] This application relates to the field of organosilicon polymer materials technology, and in particular to a polyphenylsilsesquioxane block liquid silicone rubber and its preparation method. Background Technology

[0002] Liquid silicone rubber (LSR), with its excellent flowability, injection molding capability, and environmental adaptability, is widely used in electronic packaging, biomedicine, and the automotive industry. As high-end manufacturing moves towards intelligent and lightweight designs, the application scenarios of LSR are continuously expanding to extreme operating conditions such as new energy vehicle battery sealing, aerospace high-temperature cable sheathing, and flexible electronic device packaging. For example, in new energy vehicles, LSR needs to withstand the high temperatures (>150℃) and frequent thermal cycling of battery packs over long periods; in the aerospace field, cable sheathing materials need to maintain insulation and mechanical stability in high-temperature environments above 200℃.

[0003] However, traditional LSRs based on polydimethylsiloxane (PDMS), while exhibiting excellent flexibility and processability, are prone to chain slippage, thermal oxidative degradation, and mechanical property deterioration under high temperatures (>250℃) or high-frequency dynamic loads. In dynamic environments such as vibration and impact, traditional LSRs, lacking rigid network support, are susceptible to creep or stress relaxation, leading to seal failure or interface debonding. Existing modification techniques (such as filler reinforcement) can partially improve heat resistance, but high filler content significantly increases system viscosity, sacrificing injection molding flowability and making it difficult to meet the molding requirements of complex structural parts.

[0004] Currently, modification mainly relies on physical blending or complex multi-step synthesis processes, but these methods suffer from the following technical drawbacks: Physical blending can lead to phase separation and poor interfacial compatibility, requiring the addition of compatibilizers, which not only increases costs but may also introduce impurities and reduce material purity. For example, Chinese patent CN118685038A blends liquid silicone rubber and polyurethane. To improve compatibility, it first uses polyurethane grafted with maleic anhydride and compounded with an ethylene-methyl acrylate-glycidyl methacrylate terpolymer as a compatibilizer, followed by processing using rubber-plastic premixing and high-temperature dynamic vulcanization technology. This process is complex, and the non-chemical bonding results in weak interfacial adhesion between the two phases. While nanofillers (such as silica and carbon nanotubes) can improve mechanical strength, high filler content leads to a sharp increase in system viscosity, making injection molding prone to defects such as flow marks and bubbles. For example, Chinese patent CN119432088A describes the preparation of high-strength liquid silicone rubber by adding 30-40 parts of modified silica and 1.0-5.0 parts of nano-titanium dioxide, resulting in a mixture viscosity as high as 871,000 mPa·s. For block copolymers, Chinese patent CN117924712A employs a two-step synthesis process. The first step involves activating the terminal silanol groups of polyphenylmethylsiloxane (PPS) with phenyltrichlorosilane, requiring a reaction time of 6-7 hours under anhydrous conditions. The second step involves reacting the activated PPS with polyphenylsilsesquioxane (PPSQ), also taking 6-7 hours, resulting in a total reaction cycle of 12-14 hours. This process is not only energy-intensive and inefficient, but the multiple feeding and separation steps introduce the risk of human error, making batch stability difficult to guarantee. The aforementioned methods are complex, increase system viscosity, and negatively impact product quality, and none of them achieve synergistic optimization of heat resistance and processability. Therefore, achieving directional enhancement of heat resistance while maintaining processability in liquid silicone rubber remains a problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a polyphenylsilsesquioxane block liquid silicone rubber and its preparation method.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] According to one aspect of this application, a polyphenylsilsesquioxane block liquid silicone rubber is provided, having the structure shown in Formula I:

[0008] Formula I;

[0009] In Formula I, R is independently a hydroxyl group or a group shown in Formula II;

[0010] Formula II;

[0011] The molar ratio of the group and hydroxyl group shown in Formula II is (1:1) to (1:50), preferably (1:1) to (1:40).

[0012] a and b are positive integers, and the ratio of a to b is (14:1) to (1:6.5).

[0013] According to one aspect of this application, a method for preparing polyphenylsilsesquioxane block liquid silicone rubber is provided, comprising the following steps:

[0014] S1. Polyphenylsilsesquioxane (PPSQ) and chlorine-terminated polydimethylsiloxane (Cl-PDMS-Cl) are dissolved in solvents to obtain solution I and solution II, respectively.

[0015] S2. Under inert gas protection, add solution II to solution I, stir and mix well, then add acid absorbent to react;

[0016] S3. After the reaction is complete, remove the solvent by rotary evaporation and dry to obtain the final product.

[0017] Further, in step S1, the polyphenylsilsesquioxane is a Si-OH-terminated polyphenylsilsesquioxane with a molecular weight of 2400-3500 Da, and 1 mol of polyphenylsilsesquioxane contains at least 4 mol of Si-OH, and the mass fraction of the resulting solution I is 10%-50%.

[0018] Furthermore, in step S1, the chlorine-terminated polydimethylsiloxane has a molecular weight of 7000 Da to 20000 Da, and the mass fraction of solution II is 10% to 50%.

[0019] Furthermore, the molar ratio of polyphenylsilsesquioxane to chlorinated polydimethylsiloxane is 1:(0.25-4), for example, it can be 1:0.25, 1:0.26, 1:0.27, 1:0.28, 1:0.29, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:2, 1:3, 1:4 or any range thereof.

[0020] Furthermore, in step S1, the solvent is any other solvent capable of dissolving polyphenylsilsesquioxane and chlorine-terminated polydimethylsiloxane, and is not particularly limited. For example, it can be any one or more of dichloromethane, chloroform, acetone, methyl isobutyl ketone, benzene, toluene, and xylene.

[0021] Furthermore, in step S2, the addition rate of solution II, i.e., the chlorine-terminated polydimethylsiloxane solution, is 3–12 mL / min.

[0022] Further, in step S2, the acid absorbent is selected from any one of pyridine, diethylamine, dimethylamine, triethylamine, and ammonia.

[0023] Further, in step S2, the molar ratio of the acid absorbent to Cl-PDMS-Cl is 1:(2-4).

[0024] Furthermore, in step S2, the reaction temperature is 60–100°C and the reaction time is 1–6 h.

[0025] Compared with the prior art, this application has, but is not limited to, the following beneficial effects:

[0026] This application provides a polyphenylsilsesquioxane block liquid silicone rubber. By controlling the ratio of PPSQ and Cl-PDMS-Cl blocks, the heat resistance and UV aging resistance of the obtained polyphenylsilsesquioxane block liquid silicone rubber are improved, achieving balanced optimization of material properties and providing a new generation of liquid silicone rubber with both reliability and adaptability for demanding industrial scenarios. Attached Figure Description

[0027] Figure 1 This is the FT-IR spectrum of the block liquid silicone rubber prepared in Example 1 of this application;

[0028] Figure 2 It is the block liquid silicone rubber prepared in Example 1 of this application. 1 H NMR spectrum;

[0029] Figure 3 It is the solid of the block liquid silicone rubber prepared in Example 1 of this application. 29 Si NMR spectrum;

[0030] Figure 4 This is the TG spectrum of the block liquid silicone rubber prepared in Example 1 of this application. Detailed Implementation

[0031] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of this application, but do not limit this application in any way. The following content is merely an exemplary description of the scope of protection claimed in this application, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection claimed in this application.

[0032] Unless otherwise specified, all chemical reagents used in the embodiments of this application were obtained through conventional commercial channels. Chlorine-terminated polydimethylsiloxane (CAS: 67923-13-1) was purchased from Shanghai Mairui Biochemical Technology Co., Ltd. Polyphenylsilsesquioxane is prepared by hydrolysis and polycondensation of phenylsilane compounds, phenylsilane compounds, or combinations of phenylsilane compounds with vinylsilane compounds and cycloalkylsilane compounds as raw materials; the alkylsilane compound is any one or a combination of phenyltrichlorosilane, phenyltrimethoxysilane, and phenyltriethoxysilane; the vinylsilane compound is vinyltrichlorosilane; and the cycloalkylsilane compound is cyclohexyltriethoxysilane and / or cyclohexyltrichlorosilane. In this application, the preparation method of polyphenylsilsesquioxane includes the following steps: (a) mixing a silane compound and a solvent to obtain a mixed solution; the solvent is selected from any one or more combinations of dichloromethane, trichloromethane, methyl isobutyl ketone, acetone, and toluene; the mass ratio of phenylsilane to solvent is 1g:1-10mL; (b) cooling the mixed solution to -10℃, adding an ice-water mixture, and undergoing a hydrolysis reaction to obtain a hydrolysis product; the mass ratio of the ice-water mixture to the silane compound is (0.5-10):1; (c) heating the hydrolysis product to 10-50℃ for a condensation reaction for 1-7h to obtain a condensation product; (d) removing the solvent from the condensation product, washing, and drying to obtain the final product.

[0033] In the following specific embodiments, polyphenyl silsesquioxane PPSQ-1 prepared from phenyltrichlorosilane is used as an example. Specifically, the preparation method of PPSQ-1 is as follows: phenyltrichlorosilane is dissolved in methyl isobutyl ketone at a mass-to-volume ratio of phenyltrichlorosilane to methyl isobutyl ketone of 1 g:4 mL to obtain a mixed solution. The mixed solution is cooled to -10°C, and the ice-water mixture is added to the above mixed solution at a mass ratio of 1:1.25 to the silane compound. The polycondensation reaction is carried out at 25°C for 2 h. After washing, rotary evaporation, and drying, polyphenyl silsesquioxane PPSQ-1 with a molecular weight of 2400 Da is obtained.

[0034] The present application will be further described below by way of specific embodiments.

[0035] Example 1

[0036] PPSQ-1 was dissolved in dichloromethane to prepare a 20% solution I, and Cl-PDMS-Cl (molecular weight 10000 Da) was dissolved in dichloromethane to prepare a 20% solution II. Under nitrogen protection, solution II was added to solution I at a molar ratio of 1:1 for PPSQ-1 and Cl-PDMS-Cl at a rate of 12 mL / min. After the addition was complete, the mixture was stirred at 40 °C for 10 min. Then, triethylamine (molar ratio of triethylamine to Cl-PDMS-Cl was 1:2) was added, and the mixture was heated to 60 °C and reacted for 2 h. After removing the solvent and drying, the block liquid silicone rubber was obtained and named LSR-1.

[0037] Figure 1 The image shows the FT-IR spectrum of block liquid silicone rubber LSR-1. As can be seen from the image, at 2963 cm⁻¹... -1 The absorption peak at 1425 cm⁻¹ is a characteristic peak of Si-CH₃. -1 This is the CH3 antisymmetric deformation vibration of Si-CH3, at 1259 cm⁻¹. -1 The absorption peak at 1000–1300 cm⁻¹ is due to the CH₃ symmetric vibration. -1 The characteristic peak of Si-O-Si is 788 cm⁻¹. -1 This is a stretching vibration of Si-C. LSR-1 exhibits a higher stretching vibration at 734 cm⁻¹ compared to Cl-PDMS-Cl. -1 There is an additional out-of-plane bending vibration peak of the benzene ring.

[0038] Figure 2 For LSR-1 1 The 1H NMR spectrum shows a 0.09 ppm signal peak for H on the methyl group and a 7.24 ppm signal peak for H on the benzene ring. Figure 4 Solid form of block liquid silicone rubber 29 The Si NMR spectrum shows signal peaks at -21.59 ppm and -77.24 ppm, corresponding to Si on the silanyl methyl unit and silanyl phenyl unit, respectively.

[0039] Example 2

[0040] PPSQ-1 was dissolved in dichloromethane to prepare a 50% solution I, and Cl-PDMS-Cl (molecular weight 7000 Da) was dissolved in dichloromethane to prepare a 50% solution II. Under nitrogen protection, solution II was added to solution I at a molar ratio of PPSQ-1 to Cl-PDMS-Cl of 1:0.25 at a rate of 3 mL / min. After the addition was complete, the mixture was stirred at room temperature for 1 h. Then, dimethylamine (molar ratio of dimethylamine to Cl-PDMS-Cl of 1:4) was added, and the mixture was heated to 80 °C and reacted for 5 h. After removing the solvent and drying, the block liquid silicone rubber was obtained and named LSR-2.

[0041] Example 3

[0042] PPSQ-1 was dissolved in dichloromethane to prepare a 30% solution I, and Cl-PDMS-Cl (molecular weight 7000 Da) was dissolved in dichloromethane to prepare a 30% solution II. Under nitrogen protection, solution II was added to solution I at a molar ratio of 1:2 for PPSQ-1 and Cl-PDMS-Cl at a rate of 3 mL / min. After the addition was complete, the mixture was stirred at room temperature for 30 min. Then, ammonia water (molar ratio of ammonia water to Cl-PDMS-Cl was 1:4) was added, and the mixture was heated to 100 °C and reacted for 4 h. After removing the solvent and drying, block liquid silicone rubber was obtained and named LSR-3.

[0043] Example 4

[0044] PPSQ-1 was dissolved in dichloromethane to prepare a 20% solution I, and Cl-PDMS-Cl (molecular weight 20000 Da) was dissolved in dichloromethane to prepare a 20% solution II. Under nitrogen protection, solution II was added to solution I at a molar ratio of PPSQ-1 to Cl-PDMS-Cl of 1:0.5 at a rate of 3 mL / min. After the addition was complete, the mixture was stirred at room temperature for 40 min. Then, 0.21 g of pyridine (molar ratio of pyridine to Cl-PDMS-Cl of 1:4) was added, and the mixture was heated to 70 °C and reacted for 6 h. After removing the solvent and drying, the block liquid silicone rubber was obtained and named LSR-4.

[0045] Example 5

[0046] PPSQ-1 was dissolved in dichloromethane to prepare a 10% solution I, and Cl-PDMS-Cl (molecular weight 7000 Da) was dissolved in dichloromethane to prepare a 50% solution II. Under nitrogen protection, solution II was added to solution I at a molar ratio of 1:4 for PPSQ-1 and Cl-PDMS-Cl at a rate of 3 mL / min. After the addition was complete, the mixture was stirred at room temperature for 20 min. Then, diethylamine (molar ratio of diethylamine to Cl-PDMS-Cl was 1:2) was added, and the mixture was heated to 70 °C and reacted for 6 h. After removing the solvent, the mixture was washed with water and dried to obtain block liquid silicone rubber, named LSR-5.

[0047] Example 6

[0048] The difference from Example 2 is that the molecular weight of Cl-PDMS-Cl is 23,000, and the resulting block liquid silicone rubber is named LSR-6.

[0049] Comparative Example 1

[0050] The difference from Example 1 is that the molar ratio of PPSQ-1 and Cl-PDMS-Cl is 1:6, and the resulting block liquid silicone rubber is named LSR-7.

[0051] Test case

[0052] The LSRs obtained from the above examples and comparative examples, and methylphenyl silicone oil with a molecular weight of 47000 Da (20% phenyl content) were subjected to thermogravimetric analysis (TGA) under a nitrogen atmosphere. In addition, the LSRs were placed in a UV aging test chamber and subjected to UV aging test for 720 hours with a main wavelength of 340 nm and a total power of 320 W. Then, the thermogravimetric analysis was performed under a nitrogen atmosphere.

[0053] The measurement results are shown in Table 1 below.

[0054] Table 1

[0055]

[0056] By comparing thermogravimetric data, the overall heat resistance and UV aging resistance of the polyphenylsilsesquioxane block liquid silicone rubber (LSR) prepared in the examples are higher than those of methylphenyl silicone oil. This indicates that the block method of polyphenylsilsesquioxane and polydimethylsiloxane can effectively increase the heat resistance and UV aging resistance of liquid silicone rubber.

[0057] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, this application is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope of this application should be within the protection scope of this application.

Claims

1. A polyphenylsilsesquioxane block liquid silicone rubber, characterized in that, It has the structure shown in Equation I: Equation I; In Formula I, R is independently a hydroxyl group or a group shown in Formula II; Formula II; The molar ratio of the group and hydroxyl group shown in Formula II is (1:1) to (1:50). a and b are positive integers, and the ratio of a to b is (14:1) to (1:6.5). The preparation method of the polyphenylsilsesquioxane block liquid silicone rubber includes the following steps: S1. Dissolve polyphenylsilsesquioxane and chlorine-terminated polydimethylsiloxane in dry solvents to obtain solution I and solution II, respectively. The molar ratio of polyphenylsilsesquioxane to chlorinated polydimethylsiloxane is 1:(0.25-4); S2. Under inert gas protection, add solution II to solution I, stir and mix well, then add acid absorbent to react; S3. After the reaction is complete, remove the solvent and dry to obtain the product; The preparation method of the polyphenylsilsesquioxane includes the following steps: (a) mixing a phenylsilane compound and a solvent to obtain a mixed solution; the solvent is selected from any one or more combinations of dichloromethane, trichloromethane, methyl isobutyl ketone, acetone, and toluene; the mass ratio of the phenylsilane compound to the volume of the solvent is 1g:1-10mL; (b) cooling the mixed solution to -10℃, adding an ice-water mixture, and undergoing a hydrolysis reaction to obtain a hydrolysis product; the mass ratio of the ice-water mixture to the silane compound is (0.5-10):1; (c) heating the hydrolysis product to 10-50℃ for a condensation reaction for 1-7h to obtain a condensation product; (d) removing the solvent from the condensation product, washing, and drying to obtain the product; the phenylsilane compound is any one or a combination of several of phenyltrichlorosilane, phenyltrimethoxysilane, and phenyltriethoxysilane.

2. The method for preparing the polyphenylsilsesquioxane block liquid silicone rubber according to claim 1, comprising the following steps: S1. Dissolve polyphenylsilsesquioxane and chlorine-terminated polydimethylsiloxane in dry solvents to obtain solution I and solution II, respectively. S2. Under inert gas protection, add solution II to solution I, stir and mix well, then add acid absorbent to react; S3. After the reaction is complete, remove the solvent and dry to obtain the product; The preparation method of the polyphenylsilsesquioxane includes the following steps: (a) mixing a phenylsilane compound and a solvent to obtain a mixed solution; the solvent is selected from any one or more combinations of dichloromethane, trichloromethane, methyl isobutyl ketone, acetone, and toluene; the mass ratio of the phenylsilane compound to the volume of the solvent is 1 g: 1-10 mL; (b) cooling the mixed solution to -10°C, adding an ice-water mixture, and undergoing a hydrolysis reaction to obtain a hydrolysis product; the mass ratio of the ice-water mixture to the silane compound is (0.5-10): 1; (c) heating the hydrolysis product to 10-50°C and performing a polycondensation reaction for 1-7 h to obtain a polycondensation product; (d) removing the solvent from the polycondensation product, washing, and drying to obtain the product; the phenylsilane compound is any one or a combination of several of phenyltrichlorosilane, phenyltrimethoxysilane, and phenyltriethoxysilane. The molar ratio of polyphenylsilsesquioxane to chlorinated polydimethylsiloxane is 1:(0.25-4).

3. The preparation method according to claim 2, characterized in that, The polyphenylsilsesquioxane is a Si-OH-terminated polyphenylsilsesquioxane, and 1 mol of polyphenylsilsesquioxane contains at least 4 mol of Si-OH.

4. The preparation method according to claim 2, characterized in that, The chlorine-terminated polydimethylsiloxane has a molecular weight of 7000 Da to 20000 Da.

5. The preparation method according to claim 2, characterized in that, In step S1, the solvent is selected from one or more of dichloromethane, chloroform, acetone, methyl isobutyl ketone, benzene, toluene, and xylene.

6. The preparation method according to claim 2, characterized in that, In step S2, the addition rate of solution II is 3–12 mL / min.

7. The preparation method according to claim 2, characterized in that, In step S2, the acid absorbent is selected from any one of pyridine, diethylamine, dimethylamine, triethylamine, and ammonia.

8. The preparation method according to claim 7, characterized in that, In step S2, the molar ratio of the chlorine-terminated polydimethylsiloxane to the acid absorbent is 1:(2-4).

9. The preparation method according to claim 2, characterized in that, In step S2, the reaction temperature is 60–100℃ and the reaction time is 1–6 h.

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