A self-healing bio-based thermally conductive silicone elastomer and its preparation method

Abstract

The present invention belongs to the technical field of the preparation of organosilicon polymer functional materials, and specifically relates to a self-healing bio-based thermally conductive organosilicon elastomer and a preparation method thereof. A self-healing bio-based organosilicon elastomer is synthesized by the stepwise polymerization of a bifunctional polysiloxane, an isocyanate, a small molecule monomer containing a disulfide bond, and a coumarin derivative. At the same time, a thermally conductive filler and a silane coupling agent are introduced into the system so that the thermally conductive filler is uniformly dispersed in the self-healing bio-based organosilicon elastomer, thereby realizing a high thermal conductivity of the self-healing bio-based organosilicon elastomer. The self-healing bio-based thermally conductive organosilicon elastomer is prepared from bio-based raw materials and has the advantage of being green and environmentally friendly. The self-healing bio-based thermally conductive organosilicon elastomer not only has a high thermal conductivity, but also has a simple and environmentally friendly preparation process, and a remarkable and efficient repair effect, and is mainly applicable to industries such as electronic appliances, automotive instruments, and elastomers.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of organosilicon polymer functional materials, and particularly relates to a self-healing bio-based thermally conductive organosilicon elastomer and a preparation method thereof. Background Art

[0002] Organosilicon elastomers refer to synthetic polymers with silicon-oxygen bond units in the polymer main chain, and have excellent insulation, corrosion resistance, chemical stability, and high and low temperature resistance. Due to the designability of the molecular structure of organosilicon materials, they not only play an irreplaceable role in traditional fields such as elastomers, medical devices, adhesives / sealants, coatings, and damping materials, but also have a pivotal position in emerging high-tech fields such as electronic skin, flexible sensors, electronic components, new energy storage materials, and aerospace. Among them, in the field of electronic components, with the rapid development of electronic technology in recent years, the design of electronic components has gradually become smaller and lighter. When working, their temperature will rise rapidly. If effective heat dissipation cannot be achieved, the service life of electronic components will be greatly reduced, and even explosions and fires may occur, endangering the lives of users. Therefore, the current demand for high thermal conductivity materials is becoming more and more urgent.

[0003] Traditional metal thermal conductive materials have a large density, do not meet the increasing lightweight requirements of electronic components, and have high hardness and are difficult to process. The thermally conductive organosilicon elastomer has the advantages of low density, easy processing, and high softness, which can make electronic components lightweight while meeting their heat dissipation requirements. Although the thermally conductive organosilicon elastomer has many advantages when applied to electronic components, it is inevitably affected by environmental factors such as light, high temperature, and external force during the use of electronic components, which may cause the service life of the thermally conductive organosilicon elastomer to be greatly reduced or the material to break, affecting the thermal conductivity of the material, and even causing serious accidents due to the decline of the heat dissipation effect. Therefore, it is necessary to carry out certain physical and chemical modifications on the thermally conductive organosilicon elastomer to improve its service life.

[0004] Self-healing materials were first inspired by bionics. This material can sense the external environment and self-repair the material surface and even the interior, improve the service life of the material, and save costs. Self-healing materials can be divided into intrinsic type and external aid type according to the repair principle. The external aid type is to encapsulate the repair agent in hollow structures such as microcapsules and microvascular vessels. When the material is damaged, the repair agent can be released. Although this method has a simple mechanism and is relatively commonly used, some limitations have been found in actual applications. For example, when the repair agent is used up, the material will lose its self-healing function. Therefore, current researchers have turned their attention to intrinsic self-healing materials.

[0005] Intrinsic self-healing can be divided into reversible covalent bond self-healing and reversible non-covalent bond self-healing. The former mainly includes hydrogen bonds, metal coordination bonds, host-guest interactions, etc., and the latter mainly includes disulfide bonds, Diels-Alder reactions, borate ester exchanges, etc. Among them, self-healing materials prepared by using reversible covalent bond interactions have received increasing attention due to their excellent mechanical properties. Usually, the repair process of self-healing materials containing covalent bonds can be completed through the reversible cleavage and reconstruction of covalent bonds, and most of them require external conditions to initiate, such as pH, heat, ultrasonic waves, light, and magnetic fields, etc. Summary of the Invention

[0006] The present invention provides a bio-based thermally conductive silicone elastomer with dual functions of light irradiation and heating and a preparation method thereof. Through the synergistic effect of a thermally conductive filler, a silane coupling agent, and a self-healing silicone elastomer, the thermally conductive filler is uniformly dispersed inside the silicone elastomer, which is beneficial to phonon diffusion, increases the phonon mean free path, and greatly improves the thermal conductivity of the silicone elastomer. Moreover, it solves the problems that most self-healing thermally conductive silicone elastomers can only achieve self-healing at high temperatures, with too long repair time and too low efficiency. The self-healing bio-based thermally conductive silicone elastomer of the present invention is applied in the heat dissipation field of electronic components, and the external conditions required for self-healing can be obtained at any time, which greatly improves the service life of the thermally conductive silicone elastomer, thereby improving the service life of electronic components and reducing the repair cost, and has extremely high application value. At the same time, this thermally conductive silicone elastomer is prepared by using bio-based raw materials such as cystine and coumarin derivatives, and has the advantage of being green and environmentally friendly.

[0007] The present invention adopts the following technical solutions:

[0008] The self-healing bio-based thermally conductive silicone elastomer is prepared by stepwise polymerization of a bifunctional polysiloxane, an isocyanate, a small molecule chain extender containing a disulfide bond, and a coumarin derivative monomer, and then adding a thermally conductive filler and a silane coupling agent. The reaction equation is as follows (where -NHCOO- can be replaced by -NHCONH-):

[0009]

[0010] The specific preparation method steps of the self-healing bio-based thermally conductive silicone elastomer are as follows:

[0011] (1) Add an isocyanate to the bifunctional polysiloxane that has been vacuum dehydrated and dissolved with an organic solvent, and stir at 30 - 40 °C for 2 h to obtain a viscous and transparent silicone prepolymer PDMS-1.

[0012] Among them, the bifunctional polysiloxane is aminopropyl-terminated polydimethylsiloxane or hydroxyl-terminated polydimethylsiloxane, and Mn = 5000 - 25000.

[0013] The isocyanate is one of isophorone diisocyanate trimer, 2,4-toluene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate.

[0014] The molar ratio of the isocyanate to the bifunctional polysiloxane is 3:1.

[0015] (2) Add a small molecule chain extender containing a disulfide bond dissolved in an organic solvent to the organosilicon prepolymer PDMS-1, and carry out a chain extension reaction at 30-40 °C for 1 h to obtain a viscous, transparent, light yellow polysiloxane prepolymer PDMS-2;

[0016] Among them, the small molecule chain extender containing a disulfide bond is one of cystine, 4,4'-diaminodiphenyl disulfide, and 4,4'-dihydroxydiphenyl disulfide. The molar ratio of the small molecule chain extender containing a disulfide bond to the bifunctional polysiloxane is 1:1.

[0017] (3) Add a coumarin derivative monomer dissolved in an organic solvent to PDMS-2, and carry out a capping reaction at 30-40 °C for 1 h to obtain a viscous, transparent, light yellow polysiloxane PDMS-3;

[0018] Among them, the coumarin derivative is 7-hydroxycoumarin or 4-methylumbelliferone. The molar ratio of the coumarin derivative to the bifunctional polysiloxane is 2:1.

[0019] The organic solvent in each of the above steps is one of N,N-dimethylformamide, acetone, ethyl acetate, butyl acetate, toluene, xylene, dichloromethane, and tetrahydrofuran.

[0020] (4) Add the thermal conductive filler to absolute ethanol, stir well for dispersion, and perform ultrasonic treatment for 1-2 h. Then add it to PDMS-3 together with the silane coupling agent, and stir the system at 30-40 °C for 2 h to obtain a viscous self-healing bio-based polysiloxane PDMS-4 containing the thermal conductive filler;

[0021] Among them, the thermal conductive filler is one of alumina, aluminum nitride, boron nitride, beryllium oxide, and diamond. The dosage of the thermal conductive filler is 0.2-1 times the mass of the bifunctional polysiloxane.

[0022] The silane coupling agent is one or more of KH550, KH560, KH570, KH580, KH590, KH792, KH171, KH172, KH540, and KH151, and the addition amount is 0.5-2 wt% of the thermal conductive filler.

[0023] (5) Slowly pour the viscous self-healing bio-based polysiloxane PDMS-4 containing heat-conducting fillers into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer material.

[0024] Beneficial effects:

[0025] Through the synergistic effect of heat-conducting fillers, silane coupling agents, and self-healing silicone elastomers, the heat-conducting fillers are evenly dispersed inside the silicone elastomer in the present invention, which is beneficial to phonon diffusion, increases the phonon mean free path, and greatly improves the heat conduction ability of the silicone elastomer; on the basis of achieving high thermal conductivity of the silicone elastomer, through the synergistic effect of reversible disulfide bonds and reversible coumarin cycloaddition reactions, the present invention endows the thermally conductive silicone elastomer with efficient self-healing performance, which can not only complete self-healing at 60 °C, but also be repaired under light irradiation in a human-friendly wavelength band; moreover, the present invention uses bio-based raw materials such as cystine and coumarin derivatives to prepare the silicone elastomer, making the prepared self-healing bio-based thermally conductive silicone elastomer have the advantage of being green and environmentally friendly. Description of the drawings

[0026] Figure 1 The infrared spectrum of the bio-based silicone elastomer prepared in Example 1 using cystine as a chain extender and 4-methylumbelliferone as a capping agent.

[0027] Figure 2 The self-healing process diagram of the bio-based silicone elastomer prepared in Example 1 using cystine as a chain extender and 4-methylumbelliferone as a capping agent after being irradiated with 10 μm near-infrared light for 16 min.

[0028] Figure 3 The self-healing process diagram of the bio-based silicone elastomer prepared in Example 1 using cystine as a chain extender and 4-methylumbelliferone as a capping agent after being irradiated with 365 nm UV light at 60 °C for 10 min.

[0029] Figure 4 The thermogravimetric analysis diagram of the bio-based silicone elastomer prepared in Example 1 using cystine as a chain extender and 4-methylumbelliferone as a capping agent.

[0030] Figure 5 The comparison diagram of the thermal conductivity of Examples 1-15 and Comparative Examples 1-3. Detailed implementation manners

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0032] Example 1

[0033] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and add it to a 100 ml three-necked flask that has been dried in a blast oven and treated with nitrogen. Add 2 g of hexamethylene diisocyanate and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; weigh 25 g of hexagonal boron nitride powder, add the boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then disperse it by ultrasonic treatment in an ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C, and add the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) to the reaction system simultaneously and stir at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermal conductive fillers; slowly pour the viscous polysiloxane PDMS-4 containing thermal conductive fillers into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0034] Infrared analysis shows that the characteristic peak of the isocyanate group at 2270 cm -1 disappears, indicating that the prepolymer reaction is complete; the peak near 3300 cm -1 is the characteristic peak of -NH, and the peaks at 1440 cm -1 and around 2910 cm -1 are the characteristic peaks of -CH2, the peaks at 1500 cm -1 , 1600 cm -1 are the characteristic peaks of amide around, the peak at 1700 cm -1 is the characteristic peak of carbonyl, and the peaks at 2900 cm -1 and 650 cm -1 are the characteristic peaks of -CH3 and S-S respectively. The appearance of the above characteristic peaks indicates the successful introduction of cysteine and coumarin and the successful synthesis of the self-healing bio-based thermally conductive silicone elastomer.

[0035] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ type thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into a square sheet of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.218 W·m -1 ·k -1 。

[0036] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing at 60 °C in 15 min; from Figure 2 It can be seen that the prepared self-healing bio-based thermally conductive silicone elastomer completed self-healing in 16 min under 10 μm near-infrared light; completed self-healing in 3 h under 365 nm UV light; completed self-healing in 2 h under visible light; from Figure 3 It can be seen that the prepared bio-based silicone elastomer can complete the self-healing process within 10 min under the dual conditions of heating at 60 °C and 365 nm UV light. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 14.86 MPa, and an elongation at break of 460%.

[0037] Example 2

[0038] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide and dehydrated by vacuum pumping at 100 °C for 2 hours into a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. Add 2 g of hexamethylene diisocyanate and react at 40 °C for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add 4,4'-diaminodiphenyl disulfide (0.99 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; weigh 25 g of hexagonal boron nitride powder, add the boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonically disperse it in a ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C. Take the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system at the same time, and stir at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermally conductive fillers; slowly pour the viscous polysiloxane PDMS-4 containing thermally conductive fillers into the mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0039] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.125 W·m -1 ·k -1 。

[0040] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the self-healing thermally conductive silicone elastomer could complete self-healing in 18 min at 60 °C; it could complete self-healing in 16 min under 10 μm near-infrared light illumination; it could complete self-healing in 3 h under 365 nm UV light illumination; and it could complete self-healing in 2.5 h under visible light illumination. Under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 10 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 13.72 MPa, and an elongation at break of 340%.

[0041] Example 3

[0042] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and place it in a 100 ml three-necked flask that has been dried in a blast oven and treated with nitrogen. Add 2.85 g of diphenylmethane diisocyanate and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent, and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent, and light yellow polysiloxane PDMS-3; weigh 25 g of hexagonal boron nitride powder, add the boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonically disperse it in a ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C. Take the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system simultaneously, and stir at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermally conductive fillers; slowly pour the viscous polysiloxane PDMS-4 containing thermally conductive fillers into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0043] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.028 W·m -1 ·k -1 .

[0044] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 20 min at 60 °C; it could complete self-healing in 12 min under 10 μm near-infrared light illumination; it could complete self-healing in 3 h under 365 nm UV light illumination; it could complete self-healing in 3.5 h under visible light illumination; under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 14 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 16.88 MPa, and an elongation at break of 170%.

[0045] Example 4

[0046] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 10000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and place it in a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. Add 1 g of hexamethylene diisocyanate and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.48 g) dissolved in 1.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (0.71 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; weigh 25 g of hexagonal boron nitride powder, add the boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonically disperse it in an ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C. Take the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system at the same time, and stir at 40 °C for 2 h to obtain a viscous polysiloxane containing thermally conductive filler PDMS-4; slowly pour the viscous polysiloxane containing thermally conductive filler PDMS-4 into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0047] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.223 W·m -1 ·k -1 .

[0048] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different lighting conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 29 min at 60 °C; it could complete self-healing in 20 min under 10 μm near-infrared light illumination; it could complete self-healing in 4 h under 365 nm UV light illumination; it could complete self-healing in 3.5 h under visible light illumination; under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 16 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 15.22 MPa, and an elongation at break of 290%.

[0049] Example 5

[0050] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 10000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours, place it in a 100 ml three-necked flask dried in a blast oven and treated with nitrogen, add 1.43 g of diphenylmethane diisocyanate, and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.48 g) dissolved in 1.5 ml of N,N-dimethylformamide, and react at 40 °C for 1 h to obtain a viscous, transparent, and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (0.71 g) dissolved in 2.0 ml of N,N-dimethylformamide, and react at 40 °C for 1 h to obtain a viscous, transparent, and light yellow polysiloxane PDMS-3; weigh 25 g of hexagonal boron nitride powder, add the boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, then ultrasonically disperse it in an ultrasonic cleaner with a frequency of 40 KHz for 2 h, finally dry and grind it at 100 °C, and add the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) to the reaction system simultaneously, and stir at 40 °C for 2 h to obtain a viscous polysiloxane containing thermally conductive fillers PDMS-4; slowly pour the viscous polysiloxane containing thermally conductive fillers PDMS-4 into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0051] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ type thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.438 W·m -1 ·k -1 .

[0052] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 25 min at 60 °C; it could complete self-healing in 19 min under 10 μm near-infrared light illumination; it could complete self-healing in 3.5 h under 365 nm UV light illumination; it could complete self-healing in 3 h under visible light illumination; under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 13 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 17.19 MPa, and an elongation at break of 165%.

[0053] Example 6

[0054] 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 10000) dissolved in 30 ml of N,N-dimethylformamide and dehydrated by vacuum pumping at 100 °C for 2 hours was taken and placed in a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. 1 g of hexamethylene diisocyanate was added, and the reaction was carried out under stirring at 40 °C for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; 4,4'-diaminodiphenyl disulfide (0.5 g) dissolved in 1.5 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then 4-methylumbelliferone (0.71 g) dissolved in 2.0 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; 25 g of hexagonal boron nitride powder was weighed, the boron nitride was added to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonic treatment was carried out in an ultrasonic cleaner with a frequency of 40 KHz for 2 h for dispersion. Finally, it was dried and ground at 100 °C. 10 g of the treated boron nitride and 0.2 g of silane coupling agent KH550 were simultaneously added to the reaction system, and the stirring was carried out at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermally conductive fillers; the viscous polysiloxane PDMS-4 containing thermally conductive fillers was slowly poured into a mold and cured at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0055] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ type thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.289 W·m -1 ·k -1 .

[0056] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 27 min at 60 °C; it could complete self-healing in 17 min under 10 μm near-infrared light illumination; it could complete self-healing in 3.6 h under 365 nm UV light illumination; it could complete self-healing in 3.2 h under visible light illumination; under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 16 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 10.82 MPa, and an elongation at break of 270%.

[0057] Example 7

[0058] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 20000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and place it in a 100 ml three-necked flask that has been dried in a blast oven and treated with nitrogen. Add 0.5 g of hexamethylene diisocyanate and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.24 g) dissolved in 1.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (0.36 g) dissolved in 1.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; weigh 25 g of hexagonal boron nitride powder, add the boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonically disperse it in a ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C. Take the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system simultaneously, and stir at 40 °C for 2 h to obtain a viscous polysiloxane containing thermal conductive fillers PDMS-4; slowly pour the viscous polysiloxane containing thermal conductive fillers PDMS-4 into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0059] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.108 W·m -1 ·k -1 .

[0060] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different lighting conditions. The experiment found that at 40 °C, the thermally conductive silicone elastomer could complete self-healing in 26 min; under 10 μm near-infrared light illumination, it could complete self-healing in 16 min; under 365 nm UV light illumination, it could complete self-healing in 3.7 h; under visible light illumination, it could complete self-healing in 3.3 h; under the dual conditions of heating at 80 °C and 365 nm UV light illumination, the self-healing process could be completed within 18 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 14.62 MPa, and an elongation at break of 250%.

[0061] Example 8

[0062] 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 20000) dissolved in 30 ml of N,N-dimethylformamide and dehydrated by vacuum pumping at 100 °C for 2 hours was taken and placed in a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. 0.5 g of hexamethylene diisocyanate was added, and the reaction was carried out under stirring at 40 °C for 2 h to obtain a viscous transparent polysiloxane prepolymer PDMS-1; 4,4'-diaminodiphenyl disulfide (0.25 g) dissolved in 1.0 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous transparent light yellow polysiloxane PDMS-2; then 4-methylumbelliferone (0.36 g) dissolved in 1.0 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous transparent light yellow polysiloxane PDMS-3; 25 g of hexagonal boron nitride powder was weighed, the boron nitride was added to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonic treatment was carried out in an ultrasonic cleaner with a frequency of 40 KHz for 2 h for dispersion. Finally, it was dried and ground at 100 °C. 10 g of the treated boron nitride and 0.2 g of silane coupling agent KH550 were simultaneously added to the reaction system, and the mixture was stirred at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermally conductive fillers; the viscous polysiloxane PDMS-4 containing thermally conductive fillers was slowly poured into a mold and cured at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0063] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ type thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.211 W·m -1 ·k -1 .

[0064] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 26 min at 60 °C; it could complete self-healing in 22 min under 10 μm near-infrared light illumination; it could complete self-healing in 4 h under 365 nm UV light illumination; it could complete self-healing in 3.3 h under visible light illumination; under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 16 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 13.99 MPa, and an elongation at break of 308%.

[0065] Example 9

[0066] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and place it in a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. Add 2 g of hexamethylene diisocyanate and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; weigh 25 g of alumina powder, add the alumina to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonically disperse it in an ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C. Take the treated alumina (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system simultaneously, and stir at 40 °C for 2 h to obtain a viscous polysiloxane containing thermally conductive fillers PDMS-4; slowly pour the viscous polysiloxane containing thermally conductive fillers PDMS-4 into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0067] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.014 W·m -1 ·k -1 .

[0068] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different lighting conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 20 min at 60 °C; it could complete self-healing in 16 min under 10 μm near-infrared light illumination; it could complete self-healing in 3 h under 365 nm UV light illumination; it could complete self-healing in 4 h under visible light illumination; under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 16 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 14.69 MPa, and an elongation at break of 390%.

[0069] Example 10

[0070] Take 20 g of aminopropyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours, and place it in a 100 ml three-necked flask that has been dried in a blast oven and treated with nitrogen. Add 2 g of hexamethylene diisocyanate and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; weigh 25 g of hexagonal boron nitride powder, add boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonically disperse it in an ultrasonic cleaner with a frequency of 40 KHz for 2 h, and finally dry and grind it at 100 °C. Take the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system at the same time, and stir at 40 °C for 2 h to obtain a viscous polysiloxane containing thermally conductive fillers PDMS-4; slowly pour the viscous polysiloxane containing thermally conductive fillers PDMS-4 into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0071] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ type thermal conductivity tester was used to test the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.112 W·m -1 ·k -1 .

[0072] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 16 min at 60 °C; complete self-healing in 18 min under 10 μm near-infrared light; complete self-healing in 3 h under 365 nm UV light; complete self-healing in 2 h under visible light; under the dual conditions of heating at 60 °C and 365 nm UV light, the self-healing process could be completed within 11 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 14.27 MPa, and an elongation at break of 440%.

[0073] Example 11

[0074] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and place it in a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. Add 2 g of hexamethylene diisocyanate and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then add 7-hydroxycoumarin (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; weigh 25 g of hexagonal boron nitride powder, add the boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonically disperse it in an ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C. Take the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system simultaneously, and stir at 40 °C for 2 h to obtain a viscous polysiloxane containing thermally conductive fillers PDMS-4; slowly pour the viscous polysiloxane containing thermally conductive fillers PDMS-4 into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0075] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ type thermal conductivity tester was used to test the thermal conductivity of the material. The sample was cut into a 10×10 mm square sheet and tested in parallel three times. The measured thermal conductivity was 3.074 W·m -1 ·k -1 .

[0076] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different lighting conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 20 min at 60 °C; it could complete self-healing in 16 min under 10 μm near-infrared light; it could complete self-healing in 3.5 h under 365 nm UV light; it could complete self-healing in 3 h under visible light; under the dual conditions of heating at 60 °C and 365 nm UV light, the self-healing process could be completed within 16 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 12.36 MPa, and an elongation at break of 420%.

[0077] Example 12

[0078] 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide, which had been vacuum dehydrated at 100 °C for 2 hours, was added to a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. 2 g of hexamethylene diisocyanate was added, and the reaction was carried out with stirring at 40 °C for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; 25 g of aluminum nitride powder was weighed, and the aluminum nitride was added to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonicated for 2 h in an ultrasonic cleaner with a frequency of 40 KHz for dispersion. Finally, it was dried and ground at 100 °C. 10 g of the treated aluminum nitride and 0.2 g of silane coupling agent KH550 were simultaneously added to the reaction system, and the mixture was stirred at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermally conductive fillers; the viscous polysiloxane PDMS-4 containing thermally conductive fillers was slowly poured into a mold and cured at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0079] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into 10×10 mm square sheets and tested in parallel three times. The measured thermal conductivity was 2.762 W·m -1 ·k -1 .

[0080] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing at 60 °C in 17 min; from Figure 2 it can be seen that the prepared self-healing bio-based thermally conductive silicone elastomer completed self-healing in 16 min under 10 μm near-infrared light; completed self-healing in 3 h under 365 nm UV light; completed self-healing in 2.2 h under visible light; the prepared bio-based silicone elastomer can complete the self-healing process within 14 min under the dual conditions of heating at 60 °C and 365 nm UV light. The prepared product was sampled and tested according to ASTM D882, the test speed was 500 mm / min, the tensile strength was 12.86 MPa, and the elongation at break was 340%.

[0081] Example 13

[0082] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and add it to a 100 ml three-necked flask that has been dried in a blast oven and treated with nitrogen. Add 2 g of hexamethylene diisocyanate and react at 40 °C for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; weigh 25 g of beryllium oxide powder, add beryllium oxide to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonically disperse it in an ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C. Take the treated beryllium oxide (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system at the same time, and stir at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermally conductive fillers; slowly pour the viscous polysiloxane PDMS-4 containing thermally conductive fillers into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0083] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.228 W·m -1 ·k -1 .

[0084] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing at 60 °C in 21 min; from Figure 2 it can be seen that the prepared self-healing bio-based thermally conductive silicone elastomer completed self-healing in 19 min under 10 μm near-infrared light, in 3.3 h under 365 nm UV light, and in 2.5 h under visible light. The prepared bio-based silicone elastomer could complete the self-healing process within 17 min under the dual conditions of heating at 60 °C and 365 nm UV light. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 11.06 MPa, and an elongation at break of 210%.

[0085] Example 14

[0086] 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide and dehydrated by vacuum pumping at 100 °C for 2 h was added to a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. 2 g of hexamethylene diisocyanate was added, and the reaction was carried out under stirring at 40 °C for 2 h to obtain a viscous transparent polysiloxane prepolymer PDMS-1; L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous transparent pale yellow polysiloxane PDMS-2; then 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous transparent pale yellow polysiloxane PDMS-3; 25 g of diamond powder was weighed, and the diamond was added to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonicated for 2 h in an ultrasonic cleaner with a frequency of 40 KHz for dispersion. Finally, it was dried and ground at 100 °C. 10 g of the treated diamond and 0.2 g of silane coupling agent KH550 were added to the reaction system simultaneously, and the mixture was stirred at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermally conductive fillers; the viscous polysiloxane PDMS-4 containing thermally conductive fillers was slowly poured into a mold and cured at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0087] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.308 W·m -1 ·k -1 .

[0088] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing at 60 °C in 5 h; from Figure 2 it can be seen that the prepared self-healing bio-based thermally conductive silicone elastomer completed self-healing under 10 μm near-infrared light irradiation for 4 h; it did not repair under 365 nm UV light irradiation; it did not repair under visible light irradiation; the prepared bio-based silicone elastomer could complete the self-healing process within 1.5 h under the dual conditions of heating at 60 °C and 365 nm UV light irradiation. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 7.62 MPa, and an elongation at break of 120%.

[0089] Example 15

[0090] 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide, which had been vacuum dehydrated at 100 °C for 2 h, was added to a 100 ml three-necked flask that had been dried in a blast oven and treated with nitrogen. 2 g of hexamethylene diisocyanate was added, and the reaction was carried out with stirring at 40 °C for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; then 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3; 25 g of hexagonal boron nitride powder was weighed, and the boron nitride was added to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonicated in an ultrasonic cleaner with a frequency of 40 KHz for 2 h for dispersion. Finally, it was dried and ground at 100 °C. The treated boron nitride (20 g) and the silane coupling agent KH550 (0.2 g) were simultaneously added to the reaction system, and the mixture was stirred at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-4 containing thermally conductive fillers; the viscous polysiloxane PDMS-4 containing thermally conductive fillers was slowly poured into a mold and cured at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0091] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 3.548 W·m -1 ·k -1 .

[0092] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing at 60 °C in 33 min; from Figure 2 it can be seen that the prepared self-healing bio-based thermally conductive silicone elastomer completed self-healing in 28 min under 10 μm near-infrared light; completed self-healing in 5 h under 365 nm UV light; completed self-healing in 4 h under visible light; from Figure 3 it can be seen that the prepared bio-based silicone elastomer can complete the self-healing process within 10 min under the dual conditions of heating at 60 °C and 365 nm UV light. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 14.01 MPa, and an elongation at break of 330%.

[0093] Control Example 1

[0094] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and place it in a 100 ml three-necked flask that has been dried in a blast oven and treated with nitrogen. Add 2 g of hexamethylene diisocyanate and react at 40 °C with stirring for 2 h to obtain a viscous and transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-2; weigh 25 g of hexagonal boron nitride powder, add the boron nitride to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then disperse it by ultrasonic treatment in a ultrasonic cleaner with a frequency of 40 KHz for 2 h. Finally, dry and grind it at 100 °C. Take the treated boron nitride (10 g) and silane coupling agent KH550 (0.2 g) and add them to the reaction system at the same time, and stir at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-3 containing a disulfide bond and a thermal conductive filler; slowly pour the viscous polysiloxane PDMS-3 containing a thermal conductive filler into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0095] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 2.054 W·m -1 ·k -1 .

[0096] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different lighting conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 1.2 h at 60 °C; it could complete self-healing in 50 min under 10 μm near-infrared light illumination; no self-healing phenomenon was found under 365 nm UV light illumination; it could complete self-healing in 3.2 h under visible light illumination; under the dual conditions of heating at 80 °C and 365 nm UV light illumination, the self-healing process could be completed within 25 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 9.33 MPa, and an elongation at break of 230%.

[0097] Control Example 2

[0098] 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide and dehydrated by vacuum pumping at 100 °C for 2 h was taken and placed in a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. 2 g of hexamethylene diisocyanate was added, and the reaction was carried out under stirring at 40 °C for 2 h to obtain a viscous transparent polysiloxane prepolymer PDMS-1; 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide was added, and the reaction was carried out at 40 °C for 1 h to obtain a viscous polysiloxane PDMS-2 capped with a coumarin derivative monomer; 25 g of hexagonal boron nitride powder was weighed, and the boron nitride was added to 30 ml of anhydrous ethanol with a purity ≥99.7%, and then ultrasonicated for 2 h in an ultrasonic cleaner with a frequency of 40 KHz for dispersion. Finally, it was dried and ground at 100 °C. 10 g of the treated boron nitride and 0.2 g of silane coupling agent KH550 were simultaneously added to the reaction system, and the stirring was carried out at 40 °C for 2 h to obtain a viscous polysiloxane PDMS-3 capped with a coumarin derivative monomer containing thermally conductive fillers; the viscous polysiloxane PDMS-3 capped with a coumarin derivative monomer containing thermally conductive fillers was slowly poured into a mold and cured at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer.

[0099] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ thermal conductivity tester was used to measure the thermal conductivity of the material. The sample was cut into square sheets of 10×10 mm and tested in parallel three times. The measured thermal conductivity was 2.216 W·m -1 ·k-1 。

[0100] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different lighting conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 3.5 h at 60 °C; it could complete self-healing in 2 h under 10 μm near-infrared light illumination; it could complete self-healing in 4.5 h under 365 nm UV light illumination; no self-healing phenomenon was found under visible light illumination; under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 2.8 h. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 11.56 MPa, and an elongation at break of 240%.

[0101] Control Example 3

[0102] Take 20 g of hydroxyl-terminated polydimethylsiloxane (Mn = 5000) dissolved in 30 ml of N,N-dimethylformamide that has been vacuum dehydrated at 100 °C for 2 hours and place it in a 100 ml three-necked flask dried in a blast oven and treated with nitrogen. Add 2 g of hexamethylene diisocyanate and react at 40 °C for 2 h to obtain a viscous transparent polysiloxane prepolymer PDMS-1; add L-cysteine (0.96 g) dissolved in 2.5 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous transparent pale yellow polysiloxane PDMS-2; then add 4-methylumbelliferone (1.41 g) dissolved in 2.0 ml of N,N-dimethylformamide and react at 40 °C for 1 h to obtain a viscous transparent pale yellow polysiloxane PDMS-3; slowly pour the viscous polysiloxane PDMS-3 capped with a coumarin derivative monomer containing a disulfide bond into a mold and cure at 65 °C for 24 h to obtain a self-healing bio-based silicone elastomer.

[0103] To verify the thermal conductivity of the self-healing thermally conductive silicone elastomer, a DRL-Ⅲ type thermal conductivity tester was used to test the thermal conductivity of the material. The sample was cut into 10×10 mm square sheets and tested in parallel three times. The measured thermal conductivity was 0.26 W·m -1 ·k -1 。

[0104] To verify the self-healing performance of the thermally conductive silicone elastomer, after fixing the scratch length, it was placed under heating or different light illumination conditions. The experiment found that the thermally conductive silicone elastomer could complete self-healing in 56 min at 60 °C; it could complete self-healing in 17 min under 10 μm near-infrared light illumination; it could complete self-healing in 3 h under 365 nm UV light illumination; it could complete self-healing in 3 h under visible light illumination; under the dual conditions of heating at 60 °C and 365 nm UV light illumination, the self-healing process could be completed within 11 min. The prepared product was sampled and tested according to ASTM D882, with a test speed of 500 mm / min, a tensile strength of 7.82 MPa, and an elongation at break of 360%.

Claims

1. A self-healing bio-based thermally conductive silicone elastomer, characterized in that: The preparation method of the self-healing thermally conductive silicone elastomer is as follows: (1) Add hexamethylene diisocyanate to the bifunctional polysiloxane that has been vacuum dehydrated, and dissolve it with an organic solvent. Stir at 30-40 °C for 2 h to obtain a viscous and transparent silicone prepolymer PDMS-1. The bifunctional polysiloxane is aminopropyl-terminated polydimethylsiloxane or hydroxyl-terminated polydimethylsiloxane, with Mn = 5000-25000. The molar ratio of hexamethylene diisocyanate to the bifunctional polysiloxane is 3:

1. (2) Add a small molecule chain extender containing a disulfide bond dissolved in an organic solvent to the silicone prepolymer PDMS-1. The system undergoes a chain extension reaction at 30-40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane prepolymer PDMS-2. The small molecule chain extender containing a disulfide bond is one of cystine or 4,4'-dihydroxydiphenyl disulfide. The molar ratio of the small molecule chain extender containing a disulfide bond to the bifunctional polysiloxane is 1:

1. (3) Add a coumarin derivative monomer dissolved in an organic solvent to PDMS-2. The system undergoes a capping reaction at 30-40 °C for 1 h to obtain a viscous, transparent and light yellow polysiloxane PDMS-3. The coumarin derivative is 7-hydroxycoumarin or 4-methylumbelliferone. The molar ratio of the coumarin derivative to the bifunctional polysiloxane is 2:

1. (4) Add the thermally conductive filler to absolute ethanol, stir well for dispersion, and perform ultrasonic treatment for 1-2 h. Then add it to PDMS-3 together with the silane coupling agent KH550. The system is stirred at 30-40 °C for 2 h to obtain a viscous self-healing bio-based polysiloxane containing the thermally conductive filler PDMS-4. The thermally conductive filler is boron nitride or beryllium oxide, and the dosage of the thermally conductive filler is 0.2-1 times the mass of the bifunctional polysiloxane. The addition amount of the silane coupling agent is 0.5-2 wt% of the thermally conductive filler. (5) Slowly pour the viscous self-healing bio-based polysiloxane containing the thermally conductive filler PDMS-4 into a mold and cure it at 65 °C for 24 h to obtain a self-healing bio-based thermally conductive silicone elastomer material.

2. The self-healing bio-based thermally conductive silicone elastomer according to claim 1, wherein: The organic solvent described in steps (1)-(3) is one of N,N-dimethylformamide, acetone, ethyl acetate, butyl acetate, toluene, xylene, dichloromethane, and tetrahydrofuran.

3. Use of the self-healing bio-based thermally conductive silicone elastomer according to claim 1 or 2, characterized in that: The self-healing thermally conductive silicone elastomer is applied to the heat dissipation field of electronic components.

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