A dynamically responsive self-healing silicone sealant, its application and preparation method

Abstract

The application belongs to the technical field of sealant and discloses a dynamic response type self-repairing silicone sealant, application and preparation method thereof. The dynamic response type self-repairing silicone sealant is prepared from the following raw material components: 80-120 parts of α, ω-dihydroxypolydimethylsiloxane, 10-40 parts of alkoxy-terminated polydimethylsiloxane, 5-20 parts of strain response type microcapsule, 1-8 parts of borate ester dynamic crosslinking agent, 10-40 parts of reinforcing filler, 5-15 parts of heat-conducting filler, 2-10 parts of crosslinking agent, 1-5 parts of coupling agent and 0.05-0.5 parts of catalyst. The shell material of the strain response type microcapsule contains rigid nanoparticles. The borate ester dynamic crosslinking agent is a silane coupling agent containing a borate ester bond. The dynamic response type self-repairing silicone sealant has high bonding strength and good mechanical properties, and can realize the time sequence division and cooperative mechanism of micro-crack dynamic bond repair and macro-crack threshold trigger repair.

Description

Technical Field

[0001] This invention belongs to the field of sealant technology, specifically relating to a dynamic responsive self-healing silicone sealant, its application, and preparation method. Background Technology

[0002] During service, the actuators of humanoid robot joint modules must continuously withstand dynamic loads and multi-degree-of-freedom movements, causing the sealant layer at the joints to be subjected to a combination of tensile, compressive, and shear stresses over a long period. Simultaneously, the joint modules place stringent requirements on waterproofing, dustproofing, electrical insulation, and thermal management. Silicone sealants, with their excellent resistance to high and low temperatures, flexibility, and chemical stability, have become the ideal material for such dynamic sealing applications.

[0003] However, when existing silicone sealants are used for dynamic sealing of humanoid robot joints, static repair is difficult to match the dynamic damage conditions. For example, the two-component silicone sealant disclosed in CN121736693A uses a traditional microcapsule scheme to achieve self-healing, but the rupture of the microcapsules depends on the mechanical propagation force of the crack, which is a passive repair that only responds after damage occurs. Its repair timing lags behind the occurrence of damage, making it difficult to actively intervene in the microcrack initiation stage. Dynamic covalent bond schemes, such as the silicone polymer disclosed in CN106336669A, can achieve bond exchange repair at the molecular level, but their ability to repair macroscopic cracks is limited, making it difficult to meet the damage repair needs at both the micro and macro scales. Secondly, the existing silicone sealant microcapsule schemes lack selectivity in damage response. Microcapsules may respond to cracks of any scale, prematurely consuming the repair components at the microcrack stage, resulting in insufficient repair capacity when macroscopic cracks occur. This problem is particularly prominent under dynamic fatigue conditions, where microcapsules are consumed when a large number of microcracks initiate, and the self-healing ability of the sealant declines significantly in the later stages of service. For example, CN121895885A discloses a dual self-healing butyl sealant combining a dynamic network with microcapsules. The microcapsules in this patent are a crack-responsive triggering mechanism, which fails to solve the aforementioned selective consumption problem.

[0004] In summary, current self-healing sealants have not yet systematically met the actual needs of humanoid robot joint seals for dynamic fatigue tolerance and multi-scale damage adaptive response. There is an urgent need to develop a new sealing material system with high adhesive strength, good mechanical properties, and a graded damage response that can achieve active repair of dynamic bonds in the microcrack stage and strain threshold triggered repair in the macrocrack stage. Summary of the Invention

[0005] The purpose of this invention is to provide a dynamic response self-healing silicone sealant with high bonding strength, good mechanical properties, and the ability to achieve graded damage response, including active repair of dynamic bonds in the microcrack stage and strain threshold triggered repair in the macrocrack stage, covering multi-scale damage throughout the sealant's entire life cycle.

[0006] The following technical solutions are used to achieve the above objectives.

[0007] The first aspect of this invention provides a dynamically responsive self-healing silicone sealant, prepared by means of raw materials comprising the following components in parts by weight:

[0008] 80–120 parts of α,ω-dihydroxypolydimethylsiloxane

[0009] 10-40 parts of alkoxy-terminated polydimethylsiloxane

[0010] 5-20 parts of strain-responsive microcapsules

[0011] 1-8 parts of borate ester dynamic crosslinking agent

[0012] 10-40 parts of reinforcing filler

[0013] 5-15 parts of thermally conductive filler

[0014] 2-10 parts of crosslinking agent

[0015] 1-5 parts of coupling agent

[0016] Catalyst 0.05–0.5 parts;

[0017] The strain-responsive microcapsule contains rigid nanoparticles in its shell material.

[0018] The borate ester dynamic crosslinking agent is a silane coupling agent containing borate ester bonds.

[0019] In some embodiments, the core material of the strain-responsive microcapsule is a mixture of hydroxyl-terminated polysiloxane and organotin catalyst, and the shell material of the strain-responsive microcapsule is prepared from urea-formaldehyde resin prepolymer and rigid nanoparticles.

[0020] And / or, the rigid nanoparticles are selected from at least one of nano-silica and nano-alumina.

[0021] In some embodiments, the amount of rigid nanoparticles doped is 5% to 20% of the shell material weight, preferably 5% to 15%, and more preferably 5% to 6%;

[0022] And / or, the shell thickness of the strain-responsive microcapsule is 2μm~5μm;

[0023] And / or, the average particle size of the strain-responsive microcapsules is 20 μm to 80 μm;

[0024] And / or, the core material content of the strain-responsive microcapsules is 60wt% to 80wt%;

[0025] In some embodiments, the method for preparing the strain-responsive microcapsules includes the following steps:

[0026] A core material solution was obtained by uniformly mixing hydroxyl-terminated polydimethylsiloxane and dibutyltin dilaurate.

[0027] Nano-silica was added to urea-formaldehyde resin prepolymer and ultrasonically dispersed to obtain a modified urea-formaldehyde resin prepolymer.

[0028] The core material solution was dispersed in an aqueous solution of modified urea-formaldehyde resin prepolymer with a mass concentration of 40%~50%, the pH was adjusted to 3.5~4.0, and the reaction was carried out at 40℃~50℃ for 4h~8h to obtain the strain-responsive microcapsules.

[0029] Preferably, the mass ratio of the core material solution to the modified urea-formaldehyde resin prepolymer is 1~1.5:1.

[0030] In some embodiments, the borate ester dynamic crosslinking agent is obtained by reacting boric acid with a hydroxyl-containing silane coupling agent;

[0031] Preferably, the hydroxyl-containing silane coupling agent is γ-hydroxypropyltrimethoxysilane;

[0032] And / or, the molar ratio of the boric acid to the hydroxyl-containing silane coupling agent is 1:2 to 1:3.

[0033] In some embodiments, the preparation method of the silane coupling agent containing borate ester bonds includes the following steps:

[0034] Boric acid and a hydroxyl-containing silane coupling agent are refluxed in an organic solvent for 4 to 8 hours to obtain a silane coupling agent containing borate ester bonds.

[0035] Preferably, the organic solvent is toluene;

[0036] And / or, the reaction temperature is 100℃~120℃.

[0037] In some embodiments, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 1000cp~80000cp;

[0038] And / or, the alkoxy-terminated polydimethylsiloxane has a viscosity of 1000cp~80000cp at 25°C;

[0039] And / or, the reinforcing filler is fumed silica or precipitated silica with a specific surface area of ​​150 m² / g to 400 m² / g;

[0040] And / or, the thermally conductive filler is boron nitride or aluminum oxide with a surface modified by vinyltrimethoxysilane, and the particle size is 0.5-5 μm;

[0041] And / or, the crosslinking agent is at least one of methyltriethoxysilane and vinyltriethoxysilane;

[0042] And / or, the coupling agent is at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane;

[0043] And / or, the catalyst is dibutyltin dilaurate.

[0044] In some embodiments, the product is prepared by weight from the following raw material components:

[0045] 100 parts of α,ω-dihydroxypolydimethylsiloxane

[0046] 18-22 parts of alkoxy-terminated polydimethylsiloxane

[0047] 10-14 parts of strain-responsive microcapsules

[0048] 4-6 parts of borate ester dynamic crosslinking agent

[0049] 23-27 parts of reinforcing filler

[0050] 8-12 parts of thermally conductive filler

[0051] 3-7 parts of crosslinking agent

[0052] 1-5 parts of coupling agent

[0053] Catalyst 0.05 to 0.5 parts.

[0054] A second aspect of the present invention provides an application of the dynamic responsive self-healing silicone sealant described above in the dynamic sealing of humanoid robot joints.

[0055] A third aspect of this invention provides a method for preparing the dynamically responsive self-healing silicone sealant as described above, comprising the following steps:

[0056] S1. Add α,ω-dihydroxy polydimethylsiloxane, alkoxy-terminated polydimethylsiloxane and reinforcing filler into a reactor, and knead and dehydrate under vacuum at 100-150℃ for 2-4 hours to obtain the base material;

[0057] S2: Cool the base material to 70℃~80℃, add borate ester dynamic crosslinking agent, stir and react under vacuum for 1.5~2 hours, so that the borate ester dynamic crosslinking agent is grafted onto the polysiloxane molecular chain to obtain the modified base material;

[0058] S3: Cool the modified base material to room temperature, add strain-responsive microcapsules, thermally conductive fillers, crosslinking agents, coupling agents and catalysts, and mix under vacuum conditions at a temperature of 25℃~40℃ and a stirring speed of 100rpm~300rpm for 0.5h~1.5h to obtain the dynamic response self-healing silicone sealant.

[0059] In this invention, the inventors discovered that by doping specific rigid nanoparticles into the shell material of strain-responsive microcapsules and combining them with a silane coupling agent containing borate ester bonds as a dynamic crosslinking agent, when the silicone sealant is subjected to tensile strain and microcracks are generated, the borate ester dynamic crosslinking agent can autonomously achieve self-repair of the microcracks. At this time, the stress is concentrated only around the rigid nanoparticles, which can effectively prevent the microcapsule from rupturing due to microcracks. When the sealant is subjected to excessive tensile strain locally, the shell material of the strain-responsive microcapsule selectively ruptures at the stress concentration point, releasing the repair component in the core material. The repair component repairs the macrocracks, so that the microcapsule is not consumed in the microcrack stage, but only responds when the strain reaches the threshold, ensuring that the repair component is still available when macro damage occurs. Thus, a time-sequential division of labor and synergy mechanism for dynamic bond repair of microcracks and threshold-triggered repair of macrocracks in silicone sealant is realized, covering multi-scale damage throughout the entire life cycle of the sealant. It also has the characteristics of high adhesive strength and good mechanical properties, and can be widely used in humanoid robot joint sealing, actuator housing sealing, flexible electronic packaging and other fields, providing an innovative material solution for long-term reliable sealing of robots under complex working conditions. Detailed Implementation

[0060] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0061] Unless otherwise specified, experimental methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the examples are commercially available products.

[0062] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0063] Example 1

[0064] (1) The preparation of the borate ester dynamic crosslinking agent includes the following steps:

[0065] 0.1 mol of boric acid and 0.25 mol of γ-hydroxypropyltrimethoxysilane were added to toluene and refluxed at 110 °C for 6 hours. The water generated in the reaction was removed using a Dean-Stark water separator. After the reaction was completed, toluene was removed by rotary evaporation to obtain a dynamically crosslinking agent with borate ester bonds.

[0066] (2) The preparation of strain-responsive microcapsules includes the following steps:

[0067] Core material preparation: 100 parts of hydroxyl-terminated polydimethylsiloxane (viscosity 1000 mPa·s) and 5 parts of dibutyltin dilaurate were mixed evenly to obtain a core material solution.

[0068] Shell material modification: 15wt% of nano-silica (particle size 20nm) of shell material was added to the urea-formaldehyde resin prepolymer (Zibo Huasen Adhesive Co., Ltd., item number: 011, CAS: 9011-05-6) and ultrasonically dispersed to obtain the modified urea-formaldehyde resin prepolymer.

[0069] Microcapsule preparation: The core material solution was dispersed in an aqueous phase of modified urea-formaldehyde resin prepolymer with a mass concentration of 45% by water-in-oil emulsion polymerization. The mass ratio of the core material solution to the modified urea-formaldehyde resin prepolymer was 1.2:1. The pH was adjusted to 3.5-4.0, and the reaction was carried out at 45°C for 4 hours to obtain strain-responsive microcapsules.

[0070] The average particle size of the strain-responsive microcapsules was approximately 50 μm, as determined by laser particle size analysis. The shell thickness was approximately 3 μm, as determined by transmission electron microscopy. The core material content was approximately 65 wt%, as determined by thermogravimetric analysis.

[0071] (3) The preparation of silicone sealant includes the following steps:

[0072] Weigh the raw materials according to the following weight proportions:

[0073] α,ω-dihydroxypolydimethylsiloxane (viscosity 20000 mPa·s at 25℃): 100 parts;

[0074] Alkoxy-terminated polydimethylsiloxane (viscosity 5000 mPa·s at 25°C): 20 parts;

[0075] Fumed silica (specific surface area 200 m² / g): 25 parts;

[0076] The borate ester dynamic crosslinking agent prepared in (1) above: 5 parts;

[0077] The strain-responsive microcapsules prepared in (2) above: 12 parts;

[0078] Modified boron nitride (Suzhou Napo Materials Technology Co., Ltd., grade SM-BN, particle size D50 approximately 2μm): 10 parts;

[0079] Methyltriethoxysilane: 5 parts;

[0080] KH-550 (γ-aminopropyltriethoxysilane): 2 parts;

[0081] KH-560 (γ-glycidyl etheroxypropyltrimethoxysilane): 1 part;

[0082] Dibutyltin dilaurate: 0.1 parts.

[0083] Preparation steps:

[0084] S1: α,ω-dihydroxy polydimethylsiloxane, alkoxy-terminated polydimethylsiloxane and fumed silica are added to a reaction vessel and kneaded and dehydrated at 120°C under vacuum of -0.095MPa for 3 hours to obtain the base material;

[0085] S2: Cool the base material to 75℃, add borate ester dynamic crosslinking agent, stir under vacuum -0.095MPa (100rpm) for 1.5 hours to obtain modified base material;

[0086] S3: Cool the modified base material to room temperature, add strain-responsive microcapsules, modified boron nitride, methyltriethoxysilane, KH-550, KH-560 and dibutyltin dilaurate, and mix under vacuum of -0.095MPa and temperature of 30℃ for 1 hour by stirring (200rpm) to obtain the dynamic response self-healing silicone sealant.

[0087] Example 2

[0088] (1) The preparation of the borate ester dynamic crosslinking agent is the same as in Example 1.

[0089] (2) The preparation of strain-responsive microcapsules is the same as in Example 1.

[0090] (3) The preparation of silicone sealant includes the following steps:

[0091] Weigh the raw materials according to the following weight proportions:

[0092] α,ω-dihydroxypolydimethylsiloxane (viscosity 20000 mPa·s at 25℃): 100 parts;

[0093] Alkoxy-terminated polydimethylsiloxane (viscosity 5000 mPa·s at 25°C): 20 parts;

[0094] Fumed silica (specific surface area 200 m² / g): 25 parts;

[0095] The borate ester dynamic crosslinking agent prepared in (1) above: 1 part;

[0096] The strain-responsive microcapsules prepared in (2) above: 5 parts;

[0097] Modified boron nitride (particle size 2μm): 10 parts;

[0098] Methyltriethoxysilane: 5 parts;

[0099] KH-550: 2 copies;

[0100] KH-560: 1 copy;

[0101] Dibutyltin dilaurate: 0.1 parts.

[0102] The preparation steps are the same as in Example 1.

[0103] Example 3

[0104] (1) The preparation of the borate ester dynamic crosslinking agent is the same as in Example 1.

[0105] (2) The preparation of strain-responsive microcapsules is the same as in Example 1.

[0106] (3) The preparation of silicone sealant includes the following steps:

[0107] Weigh the raw materials according to the following weight proportions:

[0108] α,ω-dihydroxypolydimethylsiloxane (viscosity 20000 mPa·s at 25℃): 100 parts;

[0109] Alkoxy-terminated polydimethylsiloxane (viscosity 5000 mPa·s at 25°C): 20 parts;

[0110] Fumed silica (specific surface area 200 m² / g): 25 parts;

[0111] The borate ester dynamic crosslinking agent prepared in (1) above: 8 parts;

[0112] The strain-responsive microcapsules prepared in (2) above: 20 parts;

[0113] Modified boron nitride (particle size 2μm): 10 parts;

[0114] Methyltriethoxysilane: 5 parts;

[0115] KH-550: 2 copies;

[0116] KH-560: 1 copy;

[0117] Dibutyltin dilaurate: 0.1 parts.

[0118] The preparation steps are the same as in Example 1.

[0119] Example 4

[0120] (1) The preparation of the borate ester dynamic crosslinking agent is the same as in Example 1.

[0121] (2) The preparation of strain-responsive microcapsules includes the following steps:

[0122] Core material preparation: Same as in Example 1.

[0123] Shell material modification: 5 wt% of nano-silica (particle size 20 nm) of shell material was added to the urea-formaldehyde resin prepolymer and ultrasonically dispersed evenly to obtain the modified urea-formaldehyde resin prepolymer.

[0124] Microcapsule preparation: Same as in Example 1.

[0125] The resulting strain-responsive microcapsules have an average particle size of about 50 μm, a shell thickness of about 3 μm, and a core material content of about 65 wt%.

[0126] (3) The raw material composition, weight and preparation of the silicone sealant are the same as those in Example 1.

[0127] Comparative Example 1

[0128] This comparative example provides a silicone sealant, which differs from Example 1 in that no borate ester dynamic crosslinking agent is added during the preparation of the silicone sealant.

[0129] The amount of other raw materials and the preparation process are completely consistent with those in Example 1.

[0130] Comparative Example 2

[0131] (1) The preparation of the borate ester dynamic crosslinking agent is the same as in Example 1.

[0132] (2) The preparation of strain-responsive microcapsules includes the following steps:

[0133] Core material preparation: Same as in Example 1.

[0134] Shell material: urea-formaldehyde resin prepolymer, without nano-silica.

[0135] Microcapsule preparation: Same as in Example 1.

[0136] The resulting strain-responsive microcapsules have an average particle size of about 50 μm, a shell thickness of about 3 μm, and a core material content of about 65 wt%.

[0137] (3) The raw material composition, weight and preparation of the silicone sealant are the same as those in Example 1.

[0138] Comparative Example 3

[0139] (1) The preparation of the borate ester dynamic crosslinking agent is the same as in Example 1.

[0140] (2) The preparation of strain-responsive microcapsules includes the following steps:

[0141] Core material preparation: Same as in Example 1.

[0142] Shell material modification: 30 wt% of nano-silica (particle size 20 nm) of shell material was added to the urea-formaldehyde resin prepolymer and ultrasonically dispersed evenly to obtain the modified urea-formaldehyde resin prepolymer.

[0143] Microcapsule preparation: Same as in Example 1.

[0144] The resulting strain-responsive microcapsules have an average particle size of about 50 μm, a shell thickness of about 3 μm, and a core material content of about 65 wt%.

[0145] (3) The raw material composition, weight and preparation of the silicone sealant are the same as those in Example 1.

[0146] Performance testing

[0147] The silicone sealant prepared in the examples and comparative examples was coated onto an aluminum alloy substrate and cured at room temperature for 3 days to a thickness of 2 mm.

[0148] Tensile strength and elongation at break: determined according to GB / T 528-2009, using type 1 dumbbell-shaped specimens, with a tensile rate of 500 mm / min.

[0149] Shear strength: Tested according to GB / T 7124-2008, with the base material being aluminum alloy 6061, an overlap length of 12.5 mm, and a tensile rate of 5 mm / min.

[0150] Thermal conductivity: determined according to GB / T 10295-2008.

[0151] Microcrack repair rate: Microcracks with a width of <50μm are created on the surface of the dumbbell-shaped specimen using a sharp blade. After repair treatment, the tensile strength is tested according to GB / T 528. Repair rate = (strength after repair / original strength) × 100%.

[0152] Strain response triggering: The specimens were stretched to 5%, 10%, 15%, 20%, 25%, and 30% pre-strain respectively. After release, the core material precipitation was detected by FT-IR, and the fracture threshold range was determined by combining the repair rate test.

[0153] Dynamic fatigue resistance: tested for 10 cycles at ±20% strain and a frequency of 2 Hz according to ASTM D5992. 5 After repeated loading cycles, the sealing performance retention rate was tested after fatigue.

[0154] Microcapsule consumption time sequence: The sample was subjected to 10 "microcrack introduction-repair" cycles. After each cycle, the change in microcapsule core material content was determined by TGA to evaluate the microcapsule integrity retention rate.

[0155] The pass / fail criteria for each test item are shown in Table 1 below:

[0156] Table 1. Pass / Fail Indicators for Test Items

[0157]

[0158] The test results of the silicone sealants prepared in the examples and comparative examples are shown in Table 2 below:

[0159] Table 2 Test Results of Silicone Sealants

[0160]

[0161] Based on the above test results, it was found that the sealants obtained in Examples 1-4 not only have high bonding strength and good mechanical properties, but also achieve a time-sequential collaborative mechanism of dynamic bond repair of microcracks and macrocrack trigger repair at a 20% tensile strain threshold by combining strain-responsive microcapsules and borate ester dynamic crosslinking agents. Meanwhile, comparing Examples 1, 4, 2, and 3, significant differences were found in the microcrack repair rate, macrocrack repair rate at a 20% tensile strain threshold, dynamic fatigue tolerance, and the timing of microcapsule consumption. This is mainly due to the different amounts of nano-silica added, which lead to changes in the relevant properties. The best effect was achieved when the amount of nano-silica added was 5% of the shell material.

[0162] Compared with Example 1, Comparative Example 1 only added strain-responsive microcapsules to the silicone sealant without adding borate ester dynamic crosslinking agent. As a result, the tensile strength and shear strength of the sealant decreased to a certain extent. At the same time, when microcracks were generated, the microcracks could not be repaired. When the crack threshold was reached, the macrocrack repair rate was low.

[0163] In summary, the dynamic response self-healing silicone sealant provided by this invention can realize a time-series division of labor and cooperation mechanism for dynamic bond repair of microcracks and threshold-triggered repair of macrocracks. It can be widely used in fields such as joint sealing of humanoid robots, housing sealing of actuators, and flexible electronic packaging, providing an innovative material solution for long-term reliable sealing of robots under complex working conditions.

[0164] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0165] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A dynamically responsive self-healing silicone sealant, characterized in that, It is prepared from raw materials comprising the following components in parts by weight: 80–120 parts of α,ω-dihydroxypolydimethylsiloxane 10-40 parts of alkoxy-terminated polydimethylsiloxane 5-20 parts of strain-responsive microcapsules 1-8 parts of borate ester dynamic crosslinking agent 10-40 parts of reinforcing filler 5-15 parts of thermally conductive filler 2-10 parts of crosslinking agent 1-5 parts of coupling agent; Catalyst 0.05–0.5 parts; The strain-responsive microcapsule contains rigid nanoparticles in its shell material. The borate ester dynamic crosslinking agent is a silane coupling agent containing borate ester bonds.

2. The dynamically responsive self-healing silicone sealant as described in claim 1, characterized in that, The core material of the strain-responsive microcapsule is a mixture of hydroxyl-terminated polysiloxane and organotin catalyst, and the shell material of the strain-responsive microcapsule is prepared from urea-formaldehyde resin prepolymer and rigid nanoparticles. And / or, the rigid nanoparticles are selected from at least one of nano-silica and nano-alumina.

3. The dynamic responsive self-healing silicone sealant as described in claim 1, characterized in that, The doping amount of the rigid nanoparticles is 5% to 20% of the shell material weight, preferably 5% to 15%, and more preferably 5% to 6%; And / or, the shell thickness of the strain-responsive microcapsule is 2μm~5μm; And / or, the average particle size of the strain-responsive microcapsules is 20 μm to 80 μm; And / or, the core material content of the strain-responsive microcapsules is 60wt% to 80wt%.

4. The dynamically responsive self-healing silicone sealant as described in claim 1, characterized in that, The method for preparing the strain-responsive microcapsules includes the following steps: A core material solution was obtained by uniformly mixing hydroxyl-terminated polydimethylsiloxane and dibutyltin dilaurate. Nano-silica was added to urea-formaldehyde resin prepolymer and ultrasonically dispersed to obtain a modified urea-formaldehyde resin prepolymer. The core material solution was dispersed in an aqueous solution of modified urea-formaldehyde resin prepolymer with a mass concentration of 40%~50%, the pH was adjusted to 3.5~4.0, and the reaction was carried out at 40℃~50℃ for 4h~8h to obtain the strain-responsive microcapsules. Preferably, the mass ratio of the core material solution to the modified urea-formaldehyde resin prepolymer is 1~1.5:

1.

5. The dynamically responsive self-healing silicone sealant as described in any one of claims 1-4, characterized in that, The borate ester dynamic crosslinking agent is obtained by reacting boric acid with a hydroxyl-containing silane coupling agent; Preferably, the hydroxyl-containing silane coupling agent is γ-hydroxypropyltrimethoxysilane; And / or, the molar ratio of the boric acid to the hydroxyl-containing silane coupling agent is 1:2 to 1:

3.

6. The dynamically responsive self-healing silicone sealant as described in any one of claims 1-4, characterized in that, The preparation method of the silane coupling agent containing borate ester bonds includes the following steps: Boric acid and a hydroxyl-containing silane coupling agent are refluxed in an organic solvent for 4 to 8 hours to obtain a silane coupling agent containing borate ester bonds. Preferably, the organic solvent is toluene; And / or, the reaction temperature is 100℃~120℃.

7. The dynamic responsive self-healing silicone sealant as described in any one of claims 1-4, characterized in that, The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25°C is 1000cp~80000cp; And / or, the alkoxy-terminated polydimethylsiloxane has a viscosity of 1000cp~80000cp at 25°C; And / or, the reinforcing filler is fumed silica or precipitated silica with a specific surface area of ​​150 m² / g to 400 m² / g; And / or, the thermally conductive filler is boron nitride or aluminum oxide with a surface modified by vinyltrimethoxysilane, and the particle size is 0.5-5 μm; And / or, the crosslinking agent is at least one of methyltriethoxysilane and vinyltriethoxysilane; And / or, the coupling agent is at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; And / or, the catalyst is dibutyltin dilaurate.

8. The dynamically responsive self-healing silicone sealant as described in any one of claims 1-4, characterized in that, It is prepared from the following raw material components in parts by weight: 100 parts of α,ω-dihydroxypolydimethylsiloxane 18-22 parts of alkoxy-terminated polydimethylsiloxane 10-14 parts of strain-responsive microcapsules 4-6 parts of borate ester dynamic crosslinking agent 23-27 parts of reinforcing filler 8-12 parts of thermally conductive filler 3-7 parts of crosslinking agent 1-5 parts of coupling agent Catalyst 0.05 to 0.5 parts.

9. The application of the dynamic responsive self-healing silicone sealant according to any one of claims 1-8 in the dynamic sealing of humanoid robot joints.

10. A method for preparing the dynamic responsive self-healing silicone sealant according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Add α,ω-dihydroxy polydimethylsiloxane, alkoxy-terminated polydimethylsiloxane and reinforcing filler into a reactor, and knead and dehydrate under vacuum at 100-150℃ for 2-4 hours to obtain the base material; S2: Cool the base material to 70℃~80℃, add borate ester dynamic crosslinking agent, stir and react under vacuum for 1.5~2 hours, so that the borate ester dynamic crosslinking agent is grafted onto the polysiloxane molecular chain to obtain the modified base material; S3: Cool the modified base material to room temperature, add strain-responsive microcapsules, thermally conductive fillers, crosslinking agents, coupling agents and catalysts, and mix under vacuum conditions at a temperature of 25℃~40℃ and a stirring speed of 100rpm~300rpm for 0.5h~1.5h to obtain the dynamic response self-healing silicone sealant.

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