A silicone material for biomimetic skin and a method for preparing the same

Abstract

This invention discloses a biomimetic skin-like silicone material and its preparation method, aiming to solve the problems of insufficient flexural strength, heat resistance, and oil resistance in biomimetic skin-like silicone materials. This invention uses octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, and trifluoropropyltrimethylcyclotrisiloxane as raw materials to synthesize polysiloxane segments with fluorinated and vinyl side chains, enhancing the chemical inertness, thermal stability, and oil resistance of the silicone material. Simultaneously, carbon nanotubes@silica and fumed silica are introduced as fillers, with carbon nanotubes serving as the reinforcing core, significantly improving the mechanical properties and flexural strength of the silicone material.

Description

Technical Field

[0001] This invention relates to the field of silicone material technology, specifically to a biomimetic skin silicone material and its preparation method. Background Technology

[0002] Bionic robots are robots that mimic the structure, function, and behavior of biological organisms, and are suitable for unstructured, dynamic interactive scenarios such as medical assistance, daily living companionship, and human-robot collaboration. Bionic skin is a key component for bionic robots to achieve functions such as precise grasping and bionic interaction. Among these, flexible silicone material has become one of the mainstream base materials for bionic skin due to its excellent flexibility, biocompatibility, and processing adaptability.

[0003] However, in the use of bionic robots, their bionic skin still has many performance shortcomings. For example, the joints and other nodes of the robot need to be bent at high frequency. During the bending process, the silicone material on the surface of these parts is prone to micro-cracks, causing the bionic skin to tear or permanently deform at these points, leading to functional failure. At the same time, the heat generated by the internal components of the bionic robot, such as motors and actuators, is difficult to dissipate quickly. The accumulated high temperature environment accelerates the aging of the silicone material, making it hard and brittle, affecting the service life of the bionic robot. In addition, in actual use, bionic robots inevitably come into contact with organic solvents such as lubricating oil. Traditional silicone has insufficient oil resistance and is prone to swelling and volume expansion after long-term contact, seriously affecting its appearance integrity and functional reliability.

[0004] In summary, improving the flexural strength and heat resistance of silicone materials, while addressing their insufficient oil resistance, is crucial for advancing the development of silicone materials and the field of biomimetic robots. Summary of the Invention

[0005] This invention aims to improve the bionic skin of bionic robots and solve the problems of insufficient flexural strength, heat resistance, and oil resistance of silicone materials used in bionic skin. It provides a silicone material for bionic skin and its preparation method.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: A method for preparing a silicone material for biomimetic skin, specifically comprising: Step 1: Mix and react octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and trifluoropropyltrimethylcyclotrisiloxane to obtain polymethylvinylfluorosiloxane; Step 2: Mix and react m-chloroperoxybenzoic acid and polymethylvinyl fluorosiloxane to obtain epoxidized polymethylvinyl fluorosiloxane; Step 3: Sodium silicate is mixed and reacted with carboxylated carbon nanotubes to obtain carbon nanotubes@silica, and then mixed with fumed silica and modified with silane coupling agent KH-560 to obtain silanized functional filler. Step 4: Mix epoxidized polymethyl vinyl fluorosiloxane, hydroxyl silicone oil, silanized functional filler and hydrogen-containing silicone oil, add platinum catalyst for vulcanization, and obtain a silicone material for biomimetic skin.

[0007] Furthermore, the preparation method of the polymethylvinylfluorosiloxane is as follows: Under nitrogen protection, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and trifluoropropyltrimethylcyclotrisiloxane were mixed and stirred evenly in an oil bath at 80-90℃. The oil bath temperature was raised to 110-120℃, tetramethylammonium hydroxide alkaline gel catalyst and decamethyltetrasiloxane were added, and the mixture was stirred at 300-400 rpm for 2-3 hours. The oil bath temperature was raised to 160-170℃, and the mixture was stirred for another 2-3 hours. After the reaction was completed, the mixture was cooled to obtain polymethylvinylfluorosiloxane.

[0008] Further, by weight, the polymethyl vinyl fluorosiloxane comprises 84-88 parts of octamethylcyclotetrasiloxane, 6-8 parts of tetramethyltetravinylcyclotetrasiloxane, 6-8 parts of trifluoropropyltrimethylcyclotrisiloxane, 0.2-0.3 parts of tetramethylammonium hydroxide alkaline gel catalyst, and 2-3 parts of decamethyltetrasiloxane.

[0009] Under the catalysis of tetramethylammonium hydroxide alkaline gel catalyst, the silicon-oxygen bonds of cyclic siloxanes break and open, followed by polymerization to achieve chain growth and form polysiloxane segments. Decamethyltetrasiloxane acts as a capping agent, controlling the polysiloxane chain length through the capping reaction. The flexible polysiloxane segments are mainly formed by the ring-opening polymerization of octamethylcyclotetrasiloxane, which has a silicon-oxygen bond as the main chain and two methyl groups attached to each silicon atom, giving silicone materials intrinsic flexibility and good tactile feel, and improving their resilience. Tetramethyltetravinylcyclotetrasiloxane introduces reactive vinyl side groups into the polysiloxane segments, partly facilitating subsequent epoxidation modification, and partly forming a stable three-dimensional network structure through vulcanization crosslinking, improving the tensile strength, tear strength, and resistance to permanent deformation of silicone materials. Trifluoropropyltrimethylcyclotrisiloxane introduces fluorinated side chains into the polysiloxane segments. The strongly polar carbon-fluorine bonds significantly reduce the surface energy of silicone materials, enhancing their chemical inertness, thermal stability, dimensional stability, and oil resistance.

[0010] Preferably, the preparation method of the tetramethylammonium hydroxide alkaline gel catalyst is as follows: Under nitrogen protection, octamethylcyclotetrasiloxane and tetramethylammonium hydroxide were mixed and stirred evenly in an oil bath at 80-90℃. The oil bath temperature was raised to 110-120℃ and the mixture was stirred at 300-400 rpm for 2-3 hours. After the reaction was completed, the mixture was cooled to obtain a tetramethylammonium hydroxide alkaline gel catalyst.

[0011] Preferably, the mass ratio of the octamethylcyclotetrasiloxane to tetramethylammonium hydroxide is (20-25):(0.4-0.5).

[0012] Furthermore, the preparation method of the epoxidized polymethyl vinyl fluorosiloxane is as follows: Under nitrogen protection, m-chloroperoxybenzoic acid was added to anhydrous chlorobenzene and stirred until homogeneous to obtain a m-chloroperoxybenzoic acid dispersion. Polymethyl vinyl fluorosiloxane was added to anhydrous chlorobenzene and stirred until homogeneous. The m-chloroperoxybenzoic acid dispersion was slowly added under a water bath at 0-5℃. The water bath temperature was raised to 20-30℃, and the mixture was stirred at 300-400 rpm for 40-48 hours. After the reaction was completed, the reaction system was transferred to ice-cold ethanol to precipitate the precipitate. The precipitate was filtered, and the filtrate was redissolved in toluene. Then, 5-10 wt% sodium bicarbonate aqueous solution and deionized water were added and washed until the pH of the aqueous phase was neutral. The mixture was separated, and the organic phase was dried with anhydrous magnesium sulfate and the solvent toluene was removed by rotary evaporation. The organic phase was then dried under vacuum at 50-60℃ for 10-14 hours to obtain epoxidized polymethyl vinyl fluorosiloxane.

[0013] Furthermore, the mass ratio of the m-chloroperoxybenzoic acid to polymethylvinylfluorosiloxane is (6-7):(100-110).

[0014] When there is an excess of vinyl groups in the side chains of polysiloxane segments, m-chloroperoxybenzoic acid oxidizes some of the vinyl groups in the polysiloxane side chains into epoxy groups, forming polysiloxanes with side chains containing vinyl groups, epoxy groups, and carbon-fluorine bonds. The newly formed epoxy groups have a polarity similar to that of the polar filler, which helps the polar filler to disperse in the polysiloxane; the introduction of epoxy groups helps to increase the rigidity of the molecular chain, improve the strength of the silicone material, and enhance the heat resistance of the polysiloxane.

[0015] Furthermore, the preparation method of the silanized functional filler is as follows: Sodium silicate was added to deionized water and stirred until homogeneous to obtain a sodium silicate solution. The pH of the sodium silicate solution was adjusted to 1-2 with phosphoric acid aqueous solution. Carboxylated carbon nanotubes were added, and the mixture was stirred at 20-30℃ and 300-400 rpm for 0.5-1 h. The pH of the mixture was adjusted to neutral with sodium hydroxide aqueous solution, and the mixture was stirred at 20-30℃ and 50-100 rpm for 20-24 h. After the reaction was completed, the mixture was filtered, washed with deionized water, and vacuum dried at 50-60℃ for 8-10 h to obtain carbon nanotubes@silicon dioxide. Carbon nanotubes@silica and fumed silica were added to a mixture of ethanol and deionized water, stirred until homogeneous, and ultrasonically dispersed for 10-20 min. The pH was adjusted to 4-5 with dilute hydrochloric acid, and silane coupling agent KH-560 was added. The mixture was stirred at 60-70℃ and 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was cooled, filtered, washed with ethanol and deionized water, and vacuum dried at 50-60℃ for 8-10 h to obtain the silanized functional filler.

[0016] Further, the mass ratio of sodium silicate to carboxylated carbon nanotubes is (10-20):(0.6-0.8); the mass ratio of carbon nanotubes@silica to fumed silica and silane coupling agent KH-560 is (4-5):(5-6):(0.15-0.25).

[0017] Under acidic conditions, sodium silicate hydrolyzes to generate silicic acid, which adsorbs onto the surface of carboxylated carbon nanotubes and condenses on their surface to form nanoscale silica particles. This leads to the in-situ growth of a silica shell structure on the carbon nanotube surface. Subsequently, this silica shell condenses with the silanol groups on the surface of fumed silica and the silanol groups generated by the hydrolysis of the silane coupling agent KH-560. The organosilicon molecules of the silane coupling agent then branch onto the fumed silica and carbon nanotubes@silica surfaces. The carbon nanotubes, acting as a reinforcing core, significantly improve the mechanical properties of the silica material. Modification with silica and the silane coupling agent ensures uniform dispersion of the filler in the polysiloxane, avoiding agglomeration that creates stress concentration points and affects the performance of the silica material. Simultaneously, the organosilicon molecular chains of the silane coupling agent and the silica shell help transfer stress from the flexible polysiloxane to the rigid filler, thereby significantly improving strength and flexural strength. In addition, the uniformly dispersed filler acts as an anchor in the polysiloxane, reducing the swelling tendency of the polymer matrix and thus enhancing the performance of the silicone material after aging or oil impregnation.

[0018] Furthermore, the preparation method of the biomimetic skin silicone material is as follows: Epoxidized polymethyl vinyl fluorosiloxane, hydroxyl silicone oil, silanized functional filler, and hydrogen-containing silicone oil are mixed and added to a mixer. The mixture is then mixed at 80-90℃ for 5-15 minutes, then heated to 130-140℃ and mixed for 30-40 minutes before sheeting and cooling to obtain a modified silicone masterbatch. The modified silicone masterbatch is then placed in a two-roll mill and passed through a thin mill 3-5 times. A platinum catalyst is added, and the mixture is cut 3-5 times on each side, then rolled 3-5 times before sheeting. The sheet is then cooled and left to stand at room temperature for 20-24 hours to obtain a modified silicone compound. The modified silicone compound is then transferred to a flat vulcanizing mill. The first-stage vulcanization temperature is set to 130-140℃, the first-stage vulcanization pressure to 10-15 MPa, and the first-stage vulcanization time to 10-15 minutes. The second-stage vulcanization temperature is set to 150-160℃, and the second-stage vulcanization time to 1.5-2 hours to obtain a biomimetic skin-like silicone material.

[0019] Furthermore, by weight, the biomimetic skin silicone material comprises 100-120 parts of epoxidized polymethyl vinyl fluorosiloxane, 20-24 parts of hydroxyl silicone oil, 20-26 parts of silanized functional filler, 2-4 parts of hydrogen-containing silicone oil, and 0.15-0.25 parts of platinum catalyst.

[0020] A biomimetic skin silicone material is prepared using any of the preparation methods described above.

[0021] Compared with the prior art, the beneficial effects of the present invention are: This invention uses octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, and trifluoropropyltrimethylcyclotrisiloxane as raw materials to synthesize polysiloxane segments with fluorinated and vinyl side chains, enhancing the chemical inertness, thermal stability, and oil resistance of silicone materials. Subsequently, under the oxidation of a small amount of m-chloroperoxybenzoic acid, some vinyl groups are converted into epoxy groups, improving the dispersion performance of polar fillers in polysiloxanes and the heat resistance and thermal stability of silicone materials. Another portion of the vinyl groups crosslinks into a three-dimensional network structure under the action of a platinum catalyst, improving the tensile strength, tear strength, and resistance to permanent deformation of silicone materials.

[0022] This invention introduces carbon nanotubes@silica and fumed silica as fillers in silicone materials. The carbon nanotubes act as a reinforcing core, significantly improving the mechanical properties and flexural strength of the silicone material. Simultaneously, the uniformly dispersed fillers act as anchors within the polysiloxane, reducing the swelling tendency of the polymer matrix and thus enhancing the performance of the silicone material after aging or oil impregnation. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention are described in detail below. It is understood that the described embodiments are only a part of the embodiments of the present invention, and not all of them. The dosages in the embodiments are all small-scale laboratory tests and can be scaled up proportionally. Based on the embodiments disclosed in this invention, all other equivalent embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0024] In the following examples and comparative examples, the carboxylated carbon nanotubes have an outer diameter of 20 nm, a length of 1 μm, and a carboxyl content of 2 wt%; the fumed silica has a particle size of 40 nm and a specific surface area of ​​200 m². 2 / g, the viscosity of the hydroxyl silicone oil at 25℃ is 50mPa·s, the hydroxyl content is 5wt%, the viscosity of the hydrogen-containing silicone oil at 25℃ is 50mPa·s, the hydrogen content is 0.5wt%, and the platinum catalyst is model CSAT-F6xxxx, sourced from BETLI.

[0025] Example 1: A method for preparing a silicone material for biomimetic skin, specifically as follows: Step 1: Under nitrogen protection, 20g of octamethylcyclotetrasiloxane and 0.4g of tetramethylammonium hydroxide were mixed and stirred evenly in an oil bath at 80℃. The oil bath temperature was raised to 120℃ and the mixture was stirred at 300rpm for 2 hours. After the reaction was completed, the mixture was cooled to obtain tetramethylammonium hydroxide alkaline gel catalyst. Step 2: Under nitrogen protection, 88g of octamethylcyclotetrasiloxane, 6g of tetramethyltetravinylcyclotetrasiloxane and 6g of trifluoropropyltrimethylcyclotrisiloxane were mixed and stirred evenly in an oil bath at 80°C. The oil bath temperature was raised to 110°C, and 0.2g of tetramethylammonium hydroxide alkaline gel catalyst and 2g of decamethyltetrasiloxane were added. The mixture was stirred at 300rpm for 3h. The oil bath temperature was raised to 160°C and the mixture was stirred for another 3h. After the reaction was completed, the mixture was cooled to obtain polymethylvinylfluorosiloxane. Step 3: Under nitrogen protection, 6g of m-chloroperoxybenzoic acid was added to 200mL of anhydrous chlorobenzene and stirred until homogeneous to obtain a m-chloroperoxybenzoic acid dispersion. 100g of polymethyl vinyl fluorosiloxane was added to 500mL of anhydrous chlorobenzene and stirred until homogeneous. The m-chloroperoxybenzoic acid dispersion was slowly added under 0℃ water bath conditions. The water bath temperature was raised to 20℃ and the reaction was stirred at 300rpm for 48h. After the reaction was completed, the reaction system was transferred to ice-cold ethanol for precipitation. After filtration, the filtrate was redissolved in toluene and washed with 5wt% sodium bicarbonate aqueous solution and deionized water until the pH of the aqueous phase was neutral. The liquid was separated, and the organic phase was dried with anhydrous magnesium sulfate and the solvent toluene was removed by rotary evaporation. The organic phase was then dried under vacuum at 50℃ for 14h to obtain epoxidized polymethyl vinyl fluorosiloxane. Step 4: Add 10g of sodium silicate to 500mL of deionized water and stir until homogeneous to obtain a sodium silicate solution. Adjust the pH of the sodium silicate solution to 2 with 10wt% phosphoric acid aqueous solution. Add 0.6g of carboxylated carbon nanotubes and stir at 30℃ and 300rpm for 1h. Adjust the pH of the mixture to neutral with 10wt% sodium hydroxide aqueous solution and stir at 30℃ and 100rpm for 24h. After the reaction is complete, filter, wash with deionized water, and vacuum dry at 60℃ for 8h to obtain carbon nanotubes@silicon dioxide. Step 5: Add 4g of carbon nanotubes@silica and 6g of fumed silica to a mixture of 180mL of ethanol and 20mL of deionized water, stir evenly, sonicate for 20min, adjust the pH to 5 with dilute hydrochloric acid, add 0.15g of silane coupling agent KH-560, stir at 60℃ and 300rpm for 8h, cool after reaction, filter, wash with ethanol and deionized water, and vacuum dry at 60℃ for 8h to obtain silanized functional filler; Step 6: Mix 100g of epoxidized polymethyl vinyl fluorosiloxane, 20g of hydroxyl silicone oil, 20g of silanized functional filler, and 2g of hydrogen-containing silicone oil, add to a mixer, mix at 80℃ for 10min, then heat to 130℃ and mix for 30min, then sheet, cool to obtain modified silicone masterbatch; put the modified silicone masterbatch into a two-roll mill, pass through it 3 times, add 0.15g of platinum catalyst, cut with left and right cutters 3 times each, roll 5 times, sheet, cool, and let stand at room temperature for 24h to obtain modified silicone compound; transfer the modified silicone compound to a flat vulcanizing machine, set the first vulcanization temperature to 130℃, the first vulcanization pressure to 15MPa, the first vulcanization time to 10min, the second vulcanization temperature to 150℃, and the second vulcanization time to 2h to obtain biomimetic skin silicone material.

[0026] Example 2: A method for preparing a silicone material for biomimetic skin, specifically as follows: Step 1: Under nitrogen protection, 22g of octamethylcyclotetrasiloxane and 0.45g of tetramethylammonium hydroxide were mixed and stirred evenly in an oil bath at 80℃. The oil bath temperature was raised to 120℃ and the mixture was stirred at 300rpm for 2 hours. After the reaction was completed, the mixture was cooled to obtain tetramethylammonium hydroxide alkaline gel catalyst. Step 2: Under nitrogen protection, 86g of octamethylcyclotetrasiloxane, 7g of tetramethyltetravinylcyclotetrasiloxane and 7g of trifluoropropyltrimethylcyclotrisiloxane were mixed and stirred evenly in an oil bath at 80°C. The oil bath temperature was raised to 110°C, and 0.25g of tetramethylammonium hydroxide alkaline gel catalyst and 2.5g of decamethyltetrasiloxane were added. The mixture was stirred at 300rpm for 3 hours. The oil bath temperature was raised to 160°C and the mixture was stirred for another 3 hours. After the reaction was completed, the mixture was cooled to obtain polymethylvinylfluorosiloxane. Step 3: Under nitrogen protection, 6.5 g of m-chloroperoxybenzoic acid was added to 200 mL of anhydrous chlorobenzene and stirred until homogeneous to obtain a m-chloroperoxybenzoic acid dispersion. 105 g of polymethyl vinyl fluorosiloxane was added to 500 mL of anhydrous chlorobenzene and stirred until homogeneous. The m-chloroperoxybenzoic acid dispersion was slowly added under 0°C water bath conditions. The water bath temperature was raised to 20°C and the mixture was stirred at 300 rpm for 48 h. After the reaction was completed, the reaction system was transferred to ice-cold ethanol to precipitate. After filtration, the filtrate was redissolved in toluene and washed with 5 wt% sodium bicarbonate aqueous solution and deionized water until the pH of the aqueous phase was neutral. The mixture was separated, and the organic phase was dried with anhydrous magnesium sulfate and the solvent toluene was removed by rotary evaporation. The organic phase was then dried under vacuum at 50°C for 14 h to obtain epoxidized polymethyl vinyl fluorosiloxane. Step 4: Add 15g of sodium silicate to 500mL of deionized water and stir until homogeneous to obtain a sodium silicate solution. Adjust the pH of the sodium silicate solution to 2 with 10wt% phosphoric acid aqueous solution. Add 0.7g of carboxylated carbon nanotubes and stir at 30℃ and 300rpm for 1h. Adjust the pH of the mixture to neutral with 10wt% sodium hydroxide aqueous solution and stir at 30℃ and 100rpm for 24h. After the reaction is complete, filter, wash with deionized water, and vacuum dry at 60℃ for 8h to obtain carbon nanotubes@silicon dioxide. Step 5: Add 4.5g of carbon nanotubes@silica and 5.5g of fumed silica to a mixture of 180mL of ethanol and 20mL of deionized water, stir evenly, sonicate for 20min, adjust the pH to 5 with dilute hydrochloric acid, add 0.2g of silane coupling agent KH-560, stir at 60℃ and 300rpm for 8h, cool after reaction, filter, wash with ethanol and deionized water, and vacuum dry at 60℃ for 8h to obtain silanized functional filler; Step 6: Mix 110g of epoxidized polymethyl vinyl fluorosiloxane, 22g of hydroxyl silicone oil, 24g of silanized functional filler, and 3g of hydrogen-containing silicone oil, add to a mixer, mix at 80℃ for 10min, then heat to 130℃ and mix for 30min, then sheet, cool to obtain modified silicone masterbatch; put the modified silicone masterbatch into a two-roll mill, pass through it three times, add 0.2g of platinum catalyst, cut with left and right cutters three times each, roll five times, sheet, cool, and let stand at room temperature for 24h to obtain modified silicone compound; transfer the modified silicone compound to a flat vulcanizing machine, set the first vulcanization temperature to 130℃, the first vulcanization pressure to 15MPa, the first vulcanization time to 10min, the second vulcanization temperature to 150℃, and the second vulcanization time to 2h to obtain biomimetic skin silicone material.

[0027] Example 3: A method for preparing a silicone material for biomimetic skin, specifically as follows: Step 1: Under nitrogen protection, 25g of octamethylcyclotetrasiloxane and 0.5g of tetramethylammonium hydroxide were mixed and stirred evenly in an oil bath at 80℃. The oil bath temperature was raised to 120℃ and the mixture was stirred at 300rpm for 2 hours. After the reaction was completed, the mixture was cooled to obtain tetramethylammonium hydroxide alkaline gel catalyst. Step 2: Under nitrogen protection, 82g of octamethylcyclotetrasiloxane, 8g of tetramethyltetravinylcyclotetrasiloxane and 8g of trifluoropropyltrimethylcyclotrisiloxane were mixed and stirred evenly in an oil bath at 80°C. The oil bath temperature was raised to 110°C, and 0.3g of tetramethylammonium hydroxide alkaline gel catalyst and 3g of decamethyltetrasiloxane were added. The mixture was stirred at 300rpm for 3 hours. The oil bath temperature was raised to 160°C and the mixture was stirred for another 3 hours. After the reaction was completed, the mixture was cooled to obtain polymethylvinylfluorosiloxane. Step 3: Under nitrogen protection, 7g of m-chloroperoxybenzoic acid was added to 200mL of anhydrous chlorobenzene and stirred until homogeneous to obtain a m-chloroperoxybenzoic acid dispersion. 110g of polymethyl vinyl fluorosiloxane was added to 500mL of anhydrous chlorobenzene and stirred until homogeneous. The m-chloroperoxybenzoic acid dispersion was slowly added under 0℃ water bath conditions. The water bath temperature was raised to 20℃ and the reaction was stirred at 300rpm for 48h. After the reaction was completed, the reaction system was transferred to ice-cold ethanol for precipitation. After filtration, the filtrate was redissolved in toluene and washed with 5wt% sodium bicarbonate aqueous solution and deionized water until the pH of the aqueous phase was neutral. The liquid was separated, and the organic phase was dried with anhydrous magnesium sulfate and the solvent toluene was removed by rotary evaporation. The organic phase was dried under vacuum at 50℃ for 14h to obtain epoxidized polymethyl vinyl fluorosiloxane. Step 4: Add 20g of sodium silicate to 500mL of deionized water and stir until homogeneous to obtain a sodium silicate solution. Adjust the pH of the sodium silicate solution to 2 with 10wt% phosphoric acid aqueous solution. Add 0.8g of carboxylated carbon nanotubes and stir at 30℃ and 300rpm for 1h. Adjust the pH of the mixture to neutral with 10wt% sodium hydroxide aqueous solution and stir at 30℃ and 100rpm for 24h. After the reaction is complete, filter, wash with deionized water, and vacuum dry at 60℃ for 8h to obtain carbon nanotubes@silicon dioxide. Step 5: Add 5g of carbon nanotubes@silica and 5g of fumed silica to a mixture of 180mL of ethanol and 20mL of deionized water, stir evenly, sonicate for 20min, adjust the pH to 5 with dilute hydrochloric acid, add 0.25g of silane coupling agent KH-560, stir at 60℃ and 300rpm for 8h, cool after the reaction is complete, filter, wash with ethanol and deionized water, and vacuum dry at 60℃ for 8h to obtain silanized functional filler; Step 6: Mix 120g of epoxidized polymethyl vinyl fluorosiloxane, 24g of hydroxyl silicone oil, 26g of silanized functional filler, and 4g of hydrogen-containing silicone oil, add to a mixer, mix at 80℃ for 10min, then heat to 130℃ and mix for 30min, then sheet, cool to obtain modified silicone masterbatch; put the modified silicone masterbatch into a two-roll mill, pass through it 3 times, add 0.25g of platinum catalyst, cut with left and right cutters 3 times each, roll 5 times, sheet, cool, and let stand at room temperature for 24h to obtain modified silicone compound; transfer the modified silicone compound to a flat vulcanizing machine, set the first vulcanization temperature to 130℃, the first vulcanization pressure to 15MPa, the first vulcanization time to 10min, the second vulcanization temperature to 150℃, and the second vulcanization time to 2h to obtain biomimetic skin silicone material.

[0028] Comparative Examples 1 to 3 are technical solutions based on Example 1, as detailed below: Comparative Example 1: This comparative example relates to a method for preparing a silicone material for biomimetic skin. The difference from Example 1 is that an equal mass of octamethylcyclotetrasiloxane is used instead of trifluoropropyltrimethylcyclotrisiloxane, specifically: Step 1: Under nitrogen protection, 94g of octamethylcyclotetrasiloxane and 6g of tetramethyltetravinylcyclotetrasiloxane were mixed and stirred evenly in an oil bath at 80°C. The oil bath temperature was raised to 110°C, and 0.2g of tetramethylammonium hydroxide alkaline gel catalyst and 2g of decamethyltetrasiloxane were added. The mixture was stirred at 300rpm for 3h. The oil bath temperature was raised to 160°C and the mixture was stirred for another 3h. After the reaction was completed, the mixture was cooled to obtain polymethylvinylsiloxane. Step 2: Under nitrogen protection, 6g of m-chloroperoxybenzoic acid was added to 200mL of anhydrous chlorobenzene and stirred until homogeneous to obtain a m-chloroperoxybenzoic acid dispersion. 100g of polymethylvinylsiloxane was added to 500mL of anhydrous chlorobenzene and stirred until homogeneous. The m-chloroperoxybenzoic acid dispersion was slowly added under 0℃ water bath conditions. The water bath temperature was raised to 20℃ and the reaction was stirred at 300rpm for 48h. After the reaction was completed, the reaction system was transferred to ice-cold ethanol for precipitation. After filtration, the filtrate was redissolved in toluene and washed with 5wt% sodium bicarbonate aqueous solution and deionized water until the pH of the aqueous phase was neutral. The liquid was separated, and the organic phase was dried with anhydrous magnesium sulfate and the solvent toluene was removed by rotary evaporation. The organic phase was dried under vacuum at 50℃ for 14h to obtain epoxidized polymethylvinylsiloxane. Step 3: Mix 100g of epoxidized polymethyl vinyl siloxane, 20g of hydroxyl silicone oil, 20g of silanized functional filler, and 2g of hydrogen-containing silicone oil, add to a mixer, mix at 80℃ for 10min, then heat to 130℃ and mix for 30min, then sheet, cool to obtain modified silicone masterbatch; put the modified silicone masterbatch into a two-roll mill, pass through it 3 times, add 0.15g of platinum catalyst, cut with left and right cutters 3 times each, roll 5 times, sheet, cool, and let stand at room temperature for 24h to obtain modified silicone compound; transfer the modified silicone compound to a flat vulcanizing machine, set the first vulcanization temperature to 130℃, the first vulcanization pressure to 15MPa, the first vulcanization time to 10min, the second vulcanization temperature to 150℃, and the second vulcanization time to 2h to obtain biomimetic skin silicone material; The preparation methods of the tetramethylammonium hydroxide alkaline gel catalyst and the silanized functional filler are the same as in Example 1.

[0029] Comparative Example 2: This comparative example relates to a method for preparing a silicone material for biomimetic skin. The difference from Example 1 is that an equal mass of polymethylvinyl fluorosiloxane is used instead of epoxidized polymethylvinyl fluorosiloxane. Specifically: Step 1: Mix 100g of polymethylvinyl fluorosiloxane, 20g of hydroxyl silicone oil, 20g of silanized functional filler, and 2g of hydrogen-containing silicone oil. Add the mixture to a mixer and mix at 80℃ for 10 minutes. Then, heat the mixture to 130℃ and mix for 30 minutes. After mixing, sheet the mixture and cool it to obtain modified silicone masterbatch. Place the modified silicone masterbatch into a two-roll mill and pass it through a thin mill three times. Add 0.15g of platinum catalyst, cut the mixture three times on each side, and roll it five times. Sheet the mixture and cool it. Let it stand at room temperature for 24 hours to obtain modified silicone compound. Transfer the modified silicone compound to a flat vulcanizing machine. Set the first vulcanization temperature to 130℃, the first vulcanization pressure to 15MPa, and the first vulcanization time to 10 minutes. Set the second vulcanization temperature to 150℃ and the second vulcanization time to 2 hours to obtain a biomimetic skin silicone material. The preparation methods of polymethylvinylfluorosiloxane and silanized functional fillers are the same as in Example 1.

[0030] Comparative Example 3: This comparative example relates to a method for preparing a silicone material for biomimetic skin. The difference from Example 1 is that an equal mass of fumed silica is used instead of carbon nanotubes@silicon dioxide. Specifically: Step 1: Add 10g of fumed silica to a mixture of 180mL ethanol and 20mL deionized water, stir well, ultrasonically disperse for 20min, adjust the pH to 5 with dilute hydrochloric acid, add 0.15g of silane coupling agent KH-560, and stir at 60℃ and 300rpm for 8h. After the reaction is complete, cool, filter, wash with ethanol and deionized water, and vacuum dry at 60℃ for 8h to obtain silanized functional filler. Step 2: Mix 100g of epoxidized polymethyl vinyl fluorosiloxane, 20g of hydroxyl silicone oil, 20g of silanized functional filler, and 2g of hydrogen-containing silicone oil, add to a mixer, mix at 80℃ for 10min, then heat to 130℃ and mix for 30min, then sheet, cool to obtain modified silicone masterbatch; put the modified silicone masterbatch into a two-roll mill, pass through it 3 times, add 0.15g of platinum catalyst, cut with left and right cutters 3 times each, roll 5 times, sheet, cool, and let stand at room temperature for 24h to obtain modified silicone compound; transfer the modified silicone compound to a flat vulcanizing machine, set the first vulcanization temperature to 130℃, the first vulcanization pressure to 15MPa, the first vulcanization time to 10min, the second vulcanization temperature to 150℃, and the second vulcanization time to 2h to obtain biomimetic skin silicone material; The preparation method of epoxidized polymethyl vinyl fluorosiloxane is the same as that in Example 1.

[0031] Comparative Example 4: This comparative example relates to a method for preparing a biomimetic skin-like silicone material. The difference from Example 1 is that the carbon nanotubes@silica and fumed silica were not modified with the silane coupling agent KH-560. Specifically: Step 1: Add 10g of sodium silicate to 500mL of deionized water and stir until homogeneous to obtain a sodium silicate solution. Adjust the pH of the sodium silicate solution to 2 with 10wt% phosphoric acid aqueous solution. Add 0.6g of carboxylated carbon nanotubes and stir at 30℃ and 300rpm for 1h. Adjust the pH of the mixture to neutral with 10wt% sodium hydroxide aqueous solution and stir at 30℃ and 100rpm for 24h. After the reaction is complete, filter, wash with deionized water, and vacuum dry at 60℃ for 8h to obtain carbon nanotubes@silicon dioxide. Step 2: Mix 100g of epoxidized polymethyl vinyl fluorosiloxane, 20g of hydroxyl silicone oil, 8g of carbon nanotubes@silica, 12g of fumed silica, and 2g of hydrogen-containing silicone oil. Add the mixture to a mixer and mix at 80℃ for 10 minutes. Then, heat the mixture to 130℃ and mix for 30 minutes. After sheeting and cooling, obtain modified silicone masterbatch. Place the modified silicone masterbatch into a two-roll mill and pass it through a thin mill three times. Add 0.15g of platinum catalyst, cut the mill three times on each side, and roll it five times. After sheeting and cooling, let it stand at room temperature for 24 hours to obtain modified silicone compound. Transfer the modified silicone compound to a flat vulcanizing machine. Set the first vulcanization temperature to 130℃, the first vulcanization pressure to 15MPa, and the first vulcanization time to 10 minutes. Set the second vulcanization temperature to 150℃ and the second vulcanization time to 2 hours to obtain a biomimetic skin silicone material. The preparation method of epoxidized polymethyl vinyl fluorosiloxane is the same as that in Example 1.

[0032] Testing: Bionic skin silicone materials were prepared according to the preparation methods of each embodiment and comparative example, and the following tests were conducted.

[0033] Tensile strength test: The test is conducted in accordance with the "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber" (GB / T 528-2009). The biomimetic skin is made of silicone material and processed into a dumbbell-shaped specimen with a size of 120mm×25mm×2mm. The center gauge length is 25mm long and 6mm wide. The specimen is clamped and fixed with the fixture of a universal testing machine. The tensile speed is set to 500mm / min, and the tensile strength of the material is tested.

[0034] Hardness test: The test is conducted in accordance with the "Determination of Hardness of Vulcanized Rubber or Thermoplastic Rubber Part 4: Determination of Indentation Hardness by Shore Hardness Tester" (GB / T 39693.4-2025). The bionic skin is made of silicone material and processed into a sheet-like sample with a size of 100mm×100mm×6mm. The sample is placed on a hard horizontal platform and the indenter of the Shore hardness tester is pressed into the sample surface to test the hardness value of the material.

[0035] Abrasion resistance test: The test is conducted in accordance with the "Determination of Abrasion Resistance of Vulcanized Rubber or Thermoplastic Rubber (Modified Lamborn Abrasion Tester Method)" (GB / T 42122-2022). The biomimetic skin is made of silicone material and processed into a disc-shaped sample with a diameter of 49 mm and a thickness of 5 mm. After weighing the initial mass of the sample, the sample is fixed with the clamps of the abrasion tester. The load is set to 40 N, the slip ratio is 30%, the sample linear speed is 50 m / min, and the abrasion time is 30 min. The mass of the sample after abrasion is measured, and the abrasion loss of the sample is calculated.

[0036] Elasticity test: The test is conducted in accordance with the "Determination of Resilience of Vulcanized Rubber" (GB / T 1681-2009). The biomimetic skin is made of silicone material and processed into a cylindrical sample with a diameter of 29 mm and a thickness of 12.5 mm. The sample is fixed horizontally using a clamp and impacted with a standard punch. The standard punch has a diameter of 12.45 mm, a mass of 0.35 kg, and an impact speed of 1.4 m / s. The rebound rate of the material is then tested.

[0037] Flexural strength test: The test is conducted in accordance with the "Determination of Flexural Cracking and Crack Growth of Vulcanized Rubber or Thermoplastic Rubber (Demosia Type)" (GB / T 13934-2006). The biomimetic skin is made of silicone material and processed into a sheet-like specimen with a size of 150mm×25mm×6.3mm. A semi-cylindrical groove with a radius of 1.5mm is opened in the center of the long side of the specimen. The two ends of the specimen are fixed by the clamps of the flexural fatigue testing machine. The middle part of the test is bent repeatedly at a frequency of 5Hz until it breaks. The number of flexural cycles at the time of material fracture is measured.

[0038] Heat resistance test: The test is conducted in accordance with the "Hot air aging and heat resistance test of vulcanized rubber or thermoplastic rubber" (GB / T3512-2014). The tensile strength of the material in its initial state is tested. The material is then placed in a 150℃ oven for hot air ventilation aging for 7 days. After aging, the material is removed and conditioned at 25℃ and 50%RH for 24 hours. The tensile strength of the material after hot air aging is then measured, and the tensile strength retention rate of the material is calculated.

[0039] Oil resistance test: The test is conducted in accordance with the "Test Method for Liquid Resistance of Vulcanized Rubber or Thermoplastic Rubber" (GB / T 1690-2010). The tensile strength of the material in its initial state is tested. The sample is then completely immersed in IRM 903 oil at 70°C for 168 hours and then removed. After conditioning at 25°C and 50%RH for 24 hours, the tensile strength retention rate of the material after oil immersion is measured.

[0040]

[0041] Conclusion: The test results show that, compared with Example 1, the biomimetic skin silicone materials prepared in Comparative Example 1 (using an equal mass of octamethylcyclotetrasiloxane instead of trifluoropropyltrimethylcyclotrisiloxane), Comparative Example 2 (using an equal mass of polymethylvinylfluorosiloxane instead of epoxidized polymethylvinylfluorosiloxane), Comparative Example 3 (using an equal mass of fumed silica instead of carbon nanotubes@silica), and Comparative Example 4 (not using silane coupling agent KH-560 to modify carbon nanotubes@silica and fumed silica) all exhibit decreased tensile strength, resilience, flexural cycles, and tensile strength retention after heat aging and oil immersion, while abrasion loss increased. The biomimetic skin silicone materials of the examples show good tensile strength, low abrasion loss, high resilience, high flexural cycles, and maintain good tensile strength even after heat aging and oil immersion. The biomimetic skin silicone material provided by this invention possesses good tensile strength, hardness, abrasion resistance, elasticity, flexural strength, heat resistance, and oil resistance.

[0042] Those skilled in the art should understand that the present invention is not limited to the details of the exemplary embodiments described above. Other specific embodiments may be adopted without departing from the spirit and essential characteristics of the invention. Therefore, the above embodiments should be considered exemplary only and not restrictive, and the scope of protection of the present invention is defined by the appended claims, not by the foregoing description. All changes within the meaning and scope of the claims and their equivalents should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a silicone gel material for biomimetic skin, characterized by: Specifically: Step 1: Mix and react octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and trifluoropropyltrimethylcyclotrisiloxane to obtain polymethylvinylfluorosiloxane; Step 2: Mix and react m-chloroperoxybenzoic acid and polymethylvinyl fluorosiloxane to obtain epoxidized polymethylvinyl fluorosiloxane; Step 3: Sodium silicate is mixed and reacted with carboxylated carbon nanotubes to obtain carbon nanotubes@silica, and then mixed with fumed silica and modified with silane coupling agent KH-560 to obtain silanized functional filler. Step 4: Mix epoxidized polymethyl vinyl fluorosiloxane, hydroxyl silicone oil, silanized functional filler and hydrogen-containing silicone oil, add platinum catalyst for vulcanization, and obtain silicone material for biomimetic skin.

2. The method for preparing a biomimetic skin silicone material according to claim 1, characterized in that: The preparation method of polymethylvinylfluorosiloxane is as follows: Under nitrogen protection, octamethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and trifluoropropyltrimethylcyclotrisiloxane were mixed and stirred evenly in an oil bath at 80-90℃. The oil bath temperature was raised to 110-120℃, tetramethylammonium hydroxide alkaline gel catalyst and decamethyltetrasiloxane were added, and the mixture was stirred at 300-400 rpm for 2-3 hours. The oil bath temperature was raised to 160-170℃, and the mixture was stirred for another 2-3 hours. After the reaction was completed, the mixture was cooled to obtain polymethylvinylfluorosiloxane.

3. The method for preparing a biomimetic skin silicone material according to claim 2, characterized in that: By weight, the polymethyl vinyl fluorosiloxane comprises 84-88 parts of octamethylcyclotetrasiloxane, 6-8 parts of tetramethyltetravinylcyclotetrasiloxane, 6-8 parts of trifluoropropyltrimethylcyclotrisiloxane, 0.2-0.3 parts of tetramethylammonium hydroxide alkaline gel catalyst, and 2-3 parts of decamethyltetrasiloxane.

4. The method for preparing a biomimetic skin silicone material according to claim 1, characterized in that: The preparation method of epoxidized polymethylvinylfluorosiloxane is as follows: Under nitrogen protection, m-chloroperoxybenzoic acid was added to anhydrous chlorobenzene and stirred until homogeneous to obtain a m-chloroperoxybenzoic acid dispersion. Polymethyl vinyl fluorosiloxane was added to anhydrous chlorobenzene and stirred until homogeneous. The m-chloroperoxybenzoic acid dispersion was slowly added under a water bath at 0-5℃. The water bath temperature was raised to 20-30℃, and the mixture was stirred at 300-400 rpm for 40-48 hours. After the reaction was completed, the reaction system was transferred to ice-cold ethanol to precipitate the precipitate. The precipitate was filtered, and the filtrate was redissolved in toluene. Then, 5-10 wt% sodium bicarbonate aqueous solution and deionized water were added and washed until the pH of the aqueous phase was neutral. The mixture was separated, and the organic phase was dried with anhydrous magnesium sulfate and the solvent toluene was removed by rotary evaporation. The organic phase was then dried under vacuum at 50-60℃ for 10-14 hours to obtain epoxidized polymethyl vinyl fluorosiloxane.

5. The method for preparing a biomimetic skin silicone material according to claim 4, characterized in that: The mass ratio of m-chloroperoxybenzoic acid to polymethylvinyl fluorosiloxane is (6-7):(100-110).

6. The method for preparing a biomimetic skin silicone material according to claim 1, characterized in that: The preparation method of silanized functional fillers is as follows: Sodium silicate was added to deionized water and stirred until homogeneous to obtain a sodium silicate solution. The pH of the sodium silicate solution was adjusted to 1-2 with phosphoric acid aqueous solution. Carboxylated carbon nanotubes were added, and the mixture was stirred at 20-30℃ and 300-400 rpm for 0.5-1 h. The pH of the mixture was adjusted to neutral with sodium hydroxide aqueous solution, and the mixture was stirred at 20-30℃ and 50-100 rpm for 20-24 h. After the reaction was completed, the mixture was filtered, washed with deionized water, and vacuum dried at 50-60℃ for 8-10 h to obtain carbon nanotubes@silicon dioxide. Carbon nanotubes@silica and fumed silica were added to a mixture of ethanol and deionized water, stirred until homogeneous, and ultrasonically dispersed for 10-20 min. The pH was adjusted to 4-5 with dilute hydrochloric acid, and silane coupling agent KH-560 was added. The mixture was stirred at 60-70℃ and 300-400 rpm for 6-8 h. After the reaction was completed, the mixture was cooled, filtered, washed with ethanol and deionized water, and vacuum dried at 50-60℃ for 8-10 h to obtain the silanized functional filler.

7. The method for preparing a biomimetic skin silicone material according to claim 6, characterized in that: The mass ratio of sodium silicate to carboxylated carbon nanotubes is (10-20):(0.6-0.8); the mass ratio of carbon nanotubes@silica to fumed silica and silane coupling agent KH-560 is (4-5):(5-6):(0.15-0.25).

8. The method for preparing a biomimetic skin silicone material according to claim 1, characterized in that: The preparation method of silicone material for biomimetic skin is as follows: Epoxidized polymethyl vinyl fluorosiloxane, hydroxyl silicone oil, silanized functional filler, and hydrogen-containing silicone oil are mixed and added to a mixer. The mixture is then mixed at 80-90℃ for 5-15 minutes, then heated to 130-140℃ and mixed for 30-40 minutes before sheeting and cooling to obtain a modified silicone masterbatch. The modified silicone masterbatch is then placed in a two-roll mill and passed through a thin mill 3-5 times. A platinum catalyst is added, and the mixture is cut 3-5 times on each side, then rolled 3-5 times before sheeting. The sheet is then cooled and left to stand at room temperature for 20-24 hours to obtain a modified silicone compound. The modified silicone compound is then transferred to a flat vulcanizing mill. The first-stage vulcanization temperature is set to 130-140℃, the first-stage vulcanization pressure to 10-15 MPa, and the first-stage vulcanization time to 10-15 minutes. The second-stage vulcanization temperature is set to 150-160℃, and the second-stage vulcanization time to 1.5-2 hours to obtain a biomimetic skin-like silicone material.

9. The method for preparing a biomimetic skin silicone material according to claim 8, characterized in that: By weight, the biomimetic skin silicone material comprises 100-120 parts of epoxidized polymethyl vinyl fluorosiloxane, 20-24 parts of hydroxyl silicone oil, 20-26 parts of silanized functional filler, 2-4 parts of hydrogen-containing silicone oil, and 0.15-0.25 parts of platinum catalyst.

10. A silicone material for biomimetic skin, characterized in that: It is prepared by any one of the preparation methods according to claims 1-9.

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