Self-adaptive repairable flexible armor and preparation method and application thereof

Abstract

The invention discloses a self-adaptive and repairable flexible armor as well as a preparation method and application thereof. The flexible armor sequentially comprises a soft elastomer layer serving as an inner layer, an impact hardening layer serving as a middle layer and a polyurea layer serving as an outer layer from bottom to top, the soft elastomer layer is connected with the impact hardening layer through a microstructure; the other surface, far away from the soft elastomer layer, of the impact hardening layer is connected with the polyurea layer through chemical bonds and hydrogen bonds. Through the multi-layer structure design, the interface bonding effect is enhanced, the integrity of the multi-layer material is improved, flexibility and high protection are both achieved, and meanwhile the self-adaptive protection and self-repairing functions are achieved. The method can be used in the fields of individual protection, soft robot protection, flexible electronic protection, emergency equipment protection and the like.

Description

Technical Field

[0001] This invention relates to the field of functional composite materials, and in particular to an adaptive, repairable flexible armor, its preparation method, and its applications. Background Technology

[0002] In fields such as national security, personal protective equipment, robotic exoskeletons, flexible electronics, and sports protection, higher performance requirements are being placed on composite structures that integrate structure and function. On the one hand, the structure needs to possess bendability, lightweight, and high energy absorption characteristics to adapt to complex and variable operating environments; on the other hand, the function needs to possess diverse properties such as self-healing, tear resistance, and puncture resistance to improve system reliability and service life. Therefore, how to integrate mechanical properties, flexible deformation capabilities, and environmental adaptability into a single composite system has become an important direction in the research of flexible protective materials.

[0003] Traditional single-component flexible protective materials generally exhibit low impact resistance and puncture resistance, and often require manual repair and replacement after damage, resulting in high usage and maintenance costs. By introducing self-healing materials—through methods such as microcapsule embedding, utilizing dynamic covalent bonds (DA bonds, SS bonds, etc.) or non-covalent bonds (H bonds, metallic coordination bonds, etc.)—mechanical properties can be autonomously restored, improving the material's durability and repeatability. However, a trade-off often exists between material strength and repair speed; high-strength materials often require longer repair times, limiting their application in emergency protection.

[0004] Polyborosiloxane is a typical smart impact-hardening material that exhibits varying strengths under different strain rates. It possesses adaptive impact resistance and lightweight characteristics, along with good repair capabilities, showing great application potential in areas such as flexible impact, damping control, and personal protective equipment. However, it relaxes its cold flow under gravity, making it difficult to maintain a stable shape. Furthermore, it is prone to absorbing water, and long-term exposure to air leads to insufficient structural stability, making it unsuitable for use alone in high-reliability protective systems.

[0005] Single materials are insufficient to meet the demands of multiple functions, making multi-layered structural designs an effective means of achieving synergistic material performance. For example, CN 115059722 B discloses an impact-resistant, self-healing multi-layered composite material that integrates self-healing and impact resistance by combining thermoplastic resin with a three-dimensional fabric-reinforced core filled with shear-thickening adhesive. CN 116855111 B discloses a biomimetic multi-level impact-resistant composite coating that solves the problem of simultaneously achieving hardness, toughness, and impact resistance in protective coating materials by alternately stacking flexible polymer layers and rigid ceramic nanoparticle layers on the carbon fiber surface. However, existing designs often emphasize the functional integration of protective materials without considering the deformability and environmental adaptability of the structure. Multi-layered structural designs for flexible protective materials with shear-hardening properties still need to be considered. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, this invention provides an adaptive, repairable flexible armor, its fabrication method, and its applications. This invention utilizes a multi-layered structural design to enhance interfacial bonding and improve the overall integrity of the multi-layered materials, achieving a balance between flexibility and high protection, while also possessing adaptive protection and self-healing capabilities. It can be used in fields such as personal protective equipment, soft robot protection, flexible electronic protection, and emergency equipment protection.

[0007] The technical solution of the present invention is as follows: The first objective of this invention is to provide an adaptive, repairable flexible armor comprising, from bottom to top, a soft elastomer layer, an impact-hardening layer, and a polyurea layer; The soft elastomer layer and the impact hardening layer are connected by a microstructure; The impact-hardened layer is connected to the polyurea layer on the opposite side from the soft elastomer layer via chemical and hydrogen bonds.

[0008] In one embodiment of the present invention, the thickness ratio of the polyurea layer, the impact-hardening layer and the soft elastomer layer is 1-3:2-4:3-7.

[0009] In one embodiment of the present invention, the thickness of the polyurea layer is 0.5-1.5 mm; the thickness of the impact hardening layer is 1-2 mm; and the thickness of the soft elastomer layer is 1.5-3.5 mm.

[0010] In one embodiment of the present invention, the polyurea layer is formed by curing polyurea resin and a curing agent; the curing conditions are: temperature of 30-40 ℃ and time of 1-2 h.

[0011] In one embodiment of the present invention, the polyurea resin is a prepolymer formed by isocyanate and polyetheramine / polyesteramine.

[0012] In one embodiment of the present invention, the isocyanate is one or more of 4,4'-diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI (liquefied MDI), and isophorone diisocyanate (IPDI).

[0013] In one embodiment of the present invention, the polyetheramine is one or more of Jeffamine D-2000, Jeffamine D-1000, and Jeffamine T-403; and the polyesteramine is one or more of PEA-1000, PEA-2000, and PCL-PEA-1000.

[0014] In one embodiment of the present invention, the curing agent is an amine compound; the amine compound is one or more of aromatic amines and aliphatic amines.

[0015] In one embodiment of the present invention, the aromatic amine is one or more of diethyltoluenediamine (DETDA), 4,4'-diaminodiphenylmethane (MDA), and 4,4'-diamino-3,3'-dimethyldiphenylmethane (NMDA); and the fatty amine is one or more of isophoronediamine (IPDA), ethylenediamine (EDA), and diethylenetriamine (DETA).

[0016] In one embodiment of the present invention, the molar ratio of isocyanate in the polyurea resin to amine in the curing agent is 1.05-1.1:1.

[0017] In one embodiment of the present invention, the polyurea layer is applied to the surface and sides of the impact-hardened layer by spraying or scraping, and then cured.

[0018] In one embodiment of the present invention, the polyurea layer serves as the outer layer of a flexible armor, providing waterproof, corrosion-resistant, and somewhat self-healing properties.

[0019] In one embodiment of the present invention, the material of the impact hardening layer is hydrogen-bonded reinforced polyborosiloxane.

[0020] In one embodiment of the present invention, the hydrogen-bonded reinforced polyborosiloxane is prepared by reacting oligomeric borosiloxane with isocyanate under the action of the catalyst dibutyltin dilaurate; the reaction conditions are: 70-90 °C under a nitrogen atmosphere for 3-4 h. Oligomeric borosilicates are obtained by polymerizing hydroxyl silicone oil with boron-containing compounds at 80-90 °C for 4-6 h.

[0021] In one embodiment of the present invention, the isocyanate is one or more selected from isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane-4,4'-diisocyanate (HMDI), and toluene diisocyanate (TDI).

[0022] In one embodiment of the present invention, the molar ratio of isocyanate in the isocyanate to hydroxyl group in the oligomeric borosilicate is 1:4-8.

[0023] In one embodiment of the present invention, the boron-containing compound is one or more of boric acid, p-hydroxyphenylboronic acid, and tetrahydroxydiboron.

[0024] In one embodiment of the present invention, the molecular weight of the hydroxyl silicone oil is 1000-3000, and the molar ratio of hydroxyl groups in the hydroxyl silicone oil to hydroxyl groups in the boron-containing compound is 2.5-3:1.

[0025] In one embodiment of the invention, the impact-hardening layer serves as an intermediate layer of the flexible armor, providing impact resistance, energy dissipation, and self-healing functions.

[0026] In one embodiment of the present invention, the soft elastomer layer is formed by curing a polysiloxane elastomer through a mold; the Young's modulus of the soft elastomer layer is 0.5-2 MPa.

[0027] In one embodiment of the present invention, the polysiloxane elastomer may be selected from polydimethylsiloxane (PDMS), Ecoflex silicone, or other silicone-based elastomer materials with similar flexibility and elastic recovery properties.

[0028] In one embodiment of the present invention, the surface of the soft elastomer layer in contact with the impact hardening layer is provided with a concave-convex microstructure.

[0029] In one embodiment of the present invention, the shape of the concave-convex microstructure is one or more of the following: triangle, rectangle, and circular serrations.

[0030] In one embodiment of the present invention, the height of the uneven microstructure accounts for 10%-30% of the thickness of the soft elastomer layer.

[0031] Mechanical locking enhances the interfacial bonding strength with the intermediate layer.

[0032] A hydrogen-bonded polyborosiloxane layer is coated on a soft elastomer layer. When heated, it softens and flows, and some of it penetrates into the microstructure. After cooling, it combines into a whole. The mechanical interlocking originates from the interpenetration of the microstructure between the two layers.

[0033] In one embodiment of the invention, the soft elastomer layer serves as the inner layer of a flexible armor, providing flexible and compliant contact functionality.

[0034] A second objective of this invention is to provide a method for preparing the aforementioned flexible armor, comprising the following steps: (1) Using microstructure molds to prepare a soft elastomer layer with microstructures on the surface; (2) Hydrogen-bonded polyborosiloxane is coated on the upper surface of the soft elastomer layer to form an impact-hardening layer; (3) Spray or scrape a mixture of polyurea resin and curing agent onto the surface of the impact-hardened layer and cure it to form a polyurea layer.

[0035] In one embodiment of the present invention, the method for preparing the above-mentioned flexible armor includes the following steps: (1) Mix the polysiloxane alkyl resin of the soft elastomer with the crosslinking agent at a mass ratio of 1-20:1, pour the mixture into a microstructure mold, remove air bubbles by vacuuming in a vacuum oven, and then cast the mold to obtain a soft elastomer layer with microstructure on the surface. (2) Hydrogen-bonded polyborosiloxane is coated on the upper surface of the soft elastomer layer and placed in an 80 ℃ oven for 1-3 h to accelerate its softening and flow until it completely fills the microstructure voids. Then it is cooled to room temperature for molding. The excess polyborosiloxane at the edges and top is trimmed with a scraper to ensure that the layer thickness meets the design requirements and forms an impact-hardened layer. (3) Mix polyurea resin and curing agent evenly according to the ratio, and then spray or scrape it onto the surface and sides of the impact hardening layer to ensure complete coverage and control the thickness direction to achieve the designed layer thickness. Heat the coated sample to cure, take it out and cool it to room temperature to obtain the flexible armor.

[0036] In one embodiment of the present invention, in step (1), the curing conditions are: curing at 50-60 ℃ for 3-4 h; in step (3), the curing conditions are: curing at 30-40 ℃ for 1-2 h.

[0037] A third objective of this invention is to provide an application of the aforementioned flexible armor for the manufacture of personal protective equipment, soft robot protection, flexible electronic protection, and emergency equipment protection products.

[0038] In one embodiment of the present invention, the above-mentioned flexible armor is used to manufacture a pneumatic gripper.

[0039] In one embodiment of the present invention, the aforementioned flexible armor is processed into flexible pneumatic tentacle units.

[0040] In one embodiment of the present invention, the flexible pneumatic tentacle unit comprises a two-layer structure: an upper layer is a flexible armor, and a lower layer is a micro-airway driving layer containing micro-airways, the two being bonded together with an adhesive. When air is supplied, the micro-airway driving layer undergoes significant deformation, exhibiting an overall driving characteristic of bending towards the flexible armor layer.

[0041] In one embodiment of the present invention, the method for preparing the pneumatic gripper includes the following steps: 1) Fabrication of the micro-airway driving layer Mix the raw materials of silicone elastomer according to the proportion, pour them into a micro-channel mold, remove air bubbles by vacuuming in a vacuum oven, and cure at 50-60 ℃ for 2-4 h. Then, cast the mold to obtain a micro-channel driving layer with micro-channels on the surface; the thickness of the micro-channels accounts for 40-60% of the thickness of the micro-channel driving layer.

[0042] The silicone elastomer is a two-component addition-type silicone rubber, one component consisting of vinyl silicone rubber and a platinum catalyst, and the other component consisting of a hydrogen-containing silane crosslinking agent; the mass ratio of the two components is 0.8-12:1; preferably, the viscosity of the mixed raw materials of the silicone elastomer is 500-3000 mPa·s.

[0043] 2) Fabrication of pneumatic tentacle unit (1) Mix the polysiloxane alkyl resin of the soft elastomer with the crosslinking agent in a certain proportion, pour it into the microstructure mold, remove the air bubbles by vacuuming in the vacuum oven, and after curing, cast the mold to obtain a soft elastomer layer with microstructure on the surface. (2) Hydrogen-bonded polyborosiloxane is coated on the upper surface of the soft elastomer layer and placed in an 80 ℃ oven for 1-3 h to accelerate its softening and flow until it completely fills the microstructure voids. Then it is cooled to room temperature for molding. The excess polyborosiloxane at the edges and top is trimmed with a scraper to ensure that the layer thickness meets the design requirements and forms an impact-hardened layer. (3) Mix polyurea resin and curing agent evenly according to the ratio, spray or scrape on the surface and sides of the impact hardening layer to ensure complete coverage, and control the thickness direction to achieve the designed layer thickness. Heat the coated sample to cure, take it out and cool it to room temperature to obtain the flexible armor.

[0044] The micro-airway driving layer is bonded to the soft elastomer layer of the flexible armor with an adhesive to obtain a single pneumatic tentacle, with the tail end led out through a capillary tube for air circulation and driving.

[0045] 3) Assembly structure The five tentacles are assembled together, and capillaries are connected to each of the five tentacles through pre-reserved channels to serve as air delivery channels. All parts are bonded together with adhesive.

[0046] The beneficial technical effects of this invention are as follows: This invention proposes an adaptive, repairable flexible armor that achieves performance integration through a multi-layer flexible composite structure. It is of great significance for advancing the development of advanced protective equipment, flexible robotic skin, extreme environment operation equipment, and intelligent protective clothing, and has broad application prospects in multiple fields such as national defense security, aerospace, and smart healthcare.

[0047] The flexible armor of this invention achieves a balance between flexibility and high-efficiency protection through the combination of three layers of materials. The outer polyurea layer provides excellent water resistance and corrosion resistance, effectively protecting the service environment of the hydrogen-bonded reinforced polyborosiloxane material and reducing performance degradation. The impact hardening properties of the middle layer of hydrogen-bonded reinforced polyborosiloxane endow the structure with an adaptive response to impacts at different rates, and the breaking and recombination of BO dynamic bonds and hydrogen bonds helps dissipate a large amount of impact energy. Furthermore, the introduction of hydrogen bonds further improves the cold flow phenomenon of polyborosiloxane, ensuring the stability of the structure. The Si-O soft chains of the inner soft silicone layer endow the material with excellent ductility, ensuring overall flexibility and compliant fit. Overall, by constructing a gradient structure with decreasing modulus from the outside to the inside, impact stress can be effectively dispersed, improving energy absorption efficiency.

[0048] The flexible armor of this invention possesses excellent self-healing capabilities. When impact penetration or puncture causes material damage, the hydrogen-bonded reinforced polyborosiloxane in the middle layer rapidly repairs the breach (<10 min) through its internal dynamic BO bonds and hydrogen bonds, ensuring the integrity of the material structure. Subsequently, the polyurea coating also heals slowly through a large number of internal hydrogen bonds (<12 h), replenishing the material's strength. Through graded self-healing, structural and strength repairs are achieved sequentially, fulfilling the need for rapid repair functionality in emergency protective materials.

[0049] The flexible armor of this invention exhibits high bonding strength between its layers. In the interface layer 1 between the outer and middle layers, a small amount of isocyanate is reserved and can polymerize with the hydroxyl groups of the polyborosiloxane on the upper surface of the middle layer, forming a chemically cross-linked connection between the two layers to create a stable interface. Simultaneously, the interlayer strength can also be enhanced through numerous hydrogen bonds. In the interface layer 2 between the middle and inner layers, mechanical interlocking is formed through a textured microstructure to further improve interlayer strength. Because polyborosiloxane and soft silicone have similar PDMS flexible long-chain structures, they can fully contact each other and form a good interface.

[0050] The flexible armor of this invention can be applied to the protection of soft pneumatic grippers. The flexible structure can adapt to large deformations and flexible actuation. At the same time, its excellent impact resistance can effectively protect the pneumatic cavity and sensitive components, avoiding damage caused by accidental collisions; its self-healing properties can automatically recover after scratches or punctures, significantly improving the durability and service life of the gripper. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the flexible armor structure of the present invention; Figure 2 This is a schematic diagram of the chemical structure of interface layer 1; Figure 3 This is a schematic diagram of the microstructure of interface layer 2; Figure 4Load-time curves of samples prepared in Examples 1-3 and Comparative Examples 1-3 under 15 J impact energy; Figure 5 A schematic diagram of the air passage structure for a pneumatic gripper; Figure 6 A schematic diagram of the capillary channel structure of a pneumatic gripper; Figure 7 A schematic diagram of a pneumatic gripper for flexible armor. Detailed Implementation

[0052] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] Example 1 A method for preparing flexible armor is as follows: (1) Mix the A and B components of Ecoflex 20 evenly in a 1:1 mass ratio, pour into a mold, and remove air bubbles by vacuum drying at 25 °C for 10 min. Then, after curing at 50 °C for 3 h, pour into a mold to obtain a soft elastomer layer with microstructure 1 on the surface, ensuring a layer thickness of 1 mm; (2) Coat 20 g of hydrogen bond-reinforced polyborosiloxane on the upper surface of the soft elastomer layer and place it in an 80°C oven for 1 h to accelerate its softening and flow until it completely fills the microstructure voids. Then cool it to room temperature and trim the excess polyborosiloxane at the edges and top with a scraper to ensure that the layer thickness is 0.6 mm. Hydrogen-bonded reinforced polyborosiloxanes were polymerized at 90 °C for 4 h using hydroxyl silicone oil with a molecular weight of 2000 and boric acid at a hydroxyl molar ratio of 2.5:1 to obtain oligomeric borosiloxanes. The polymers were then heated in an open environment for 2 h to remove moisture. After cooling to room temperature, isophorone diisocyanate (IPDI) (1 / 8 molar of the hydroxyl groups in the oligomeric borosiloxanes) and dibutyltin dilaurate (catalyst) (0.05% by mass of the reactants) were added. The reaction was carried out at 80 °C under a nitrogen atmosphere for 4 h. After cooling to room temperature, the desired product was obtained. (3) Mix polyurea resin and curing agent diethyltoluene diamine (DETDA) evenly at a molar ratio of -NCO to -NH2 of 1.05:1, and then spray the mixture onto the surface and sides of the polyborosiloxane to ensure complete coverage and control the thickness to 0.4 mm. Cure the coated sample at 35°C for 1.5 h, then remove and cool to room temperature; The polyurea resin is a prepolymer of carbodiimide-modified MDI (liquefied MDI) and polyesteramine (PEA-1000), with an -NCO content of 17%.

[0054] Example 2 A method for preparing flexible armor is as follows: (1) Mix the A and B components of Ecoflex 20 evenly in a 1:1 mass ratio, pour into a mold, and remove air bubbles by vacuuming at 25 ℃ for 10 min in a vacuum oven. Then, after curing at 50 ℃ for 3 h, cast to obtain a soft elastomer layer with microstructure 2 on the surface, ensuring a layer thickness of 1.5 mm; (2) 20 g of hydrogen-bonded reinforced polyborosiloxane was coated on the upper surface of the soft elastomer layer and placed in an 80°C oven for 2 h to accelerate its softening and flow until it completely filled the microstructure voids. After cooling to room temperature, excess polyborosiloxane at the edges and top was trimmed with a scraper to ensure a layer thickness of 1 mm; Hydrogen-bonded reinforced polyborosiloxanes were polymerized at 90 °C for 4 h using hydroxyl silicone oil with a molecular weight of 2000 and boric acid in a molar ratio of 2.8:1 to obtain oligomeric borosiloxanes. The polymers were then heated in an open environment for 2 h to remove moisture. After cooling to room temperature, isophorone diisocyanate (IPDI) (1 / 6 molar of the hydroxyl groups in the oligomeric borosiloxanes) and dibutyltin dilaurate (catalyst) (0.05% by mass of the reactants) were added. The reaction was carried out at 80 °C under a nitrogen atmosphere for 4 h. After cooling to room temperature, the desired product was obtained. (3) Mix polyurea resin and curing agent isophorone diamine (IPDA) evenly at a molar ratio of -NCO to -NH2 of 1.08:1, and then spray it onto the surface and sides of polyborosiloxane to ensure complete coverage and control the thickness in the direction of 0.5 mm. Cure the coated sample at 40℃ for 2 h, and then remove it and cool it to room temperature.

[0055] The polyurea resin is a prepolymer of 4,4'-diphenylmethane diisocyanate (MDI) and polyetheramine (Jeffamine D-2000), with an -NCO content of 13%.

[0056] Example 3 A method for preparing flexible armor is as follows: (1) Mix the A and B components of Ecoflex 20 evenly in a 1:1 mass ratio, pour into a mold, and remove air bubbles by vacuuming at 25 °C for 10 min in a vacuum oven. Then, after curing at 50 °C for 3 h, cast to obtain a soft elastomer layer with microstructure 3 on the surface, ensuring a layer thickness of 2 mm; (2) 20 g of hydrogen-bonded reinforced polyborosiloxane was coated on the upper surface of the soft elastomer layer and placed in an 80°C oven for 3 h to accelerate its softening and flow until it completely filled the microstructure voids. After cooling to room temperature, excess polyborosiloxane at the edges and top was trimmed with a scraper to ensure a layer thickness of 1.5 mm; Hydrogen-bonded reinforced polyborosiloxanes were polymerized at 90 °C for 4 h using hydroxyl silicone oil with a molecular weight of 2000 and boric acid in a molar ratio of 3:1 to obtain oligomeric borosiloxanes. The polymers were then heated in an open environment for 2 h to remove moisture. After cooling to room temperature, isophorone diisocyanate (IPDI) (1 / 4 molar of the hydroxyl groups in the oligomeric borosiloxanes) and dibutyltin dilaurate (catalyst) (0.05% by mass of the reactants) were added. The reaction was carried out at 80 °C under a nitrogen atmosphere for 4 h. After cooling to room temperature, the desired product was obtained. (3) Mix polyurea resin and curing agent 4,4'-diaminodiphenylmethane (MDA) evenly at a molar ratio of -NCO to -NH2 of 1.1:1, and then coat the mixture onto the surface and sides of the polyborosiloxane to ensure complete coverage and control the thickness to 1 mm. Cure the coated sample at 30°C for 2 h, then remove and cool to room temperature; Polyurea resin is a prepolymer of isophorone diisocyanate (IPDI) and polyesteramine (PEA-1000) with an -NCO content of 9%.

[0057] Comparative Example 1 (1) Mix the A and B components of Ecoflex 20 evenly in a 1:1 mass ratio, pour into a mold, and remove air bubbles by vacuum drying at 25 °C for 10 min. Then, after curing at 50 °C for 3 h, pour into a mold to obtain a soft elastomer layer without microstructure on the surface, ensuring a layer thickness of 1 mm; (2) Coat 20 g of hydrogen bond-reinforced polyborosiloxane on the upper surface of the soft elastomer layer, and trim the excess polyborosiloxane at the edges and top with a scraper to ensure that the layer thickness is 0.6 mm; Hydrogen-bonded reinforced polyborosiloxanes were polymerized at 90 °C for 4 h using hydroxyl silicone oil with a molecular weight of 2000 and boric acid at a hydroxyl molar ratio of 2.5:1 to obtain oligomeric borosiloxanes. The polymers were then heated in an open environment for 2 h to remove moisture. After cooling to room temperature, isophorone diisocyanate (IPDI) (1 / 8 molar of the hydroxyl groups in the oligomeric borosiloxanes) and dibutyltin dilaurate (catalyst) (0.05% by mass of the reactants) were added. The reaction was carried out at 80 °C under a nitrogen atmosphere for 4 h. After cooling to room temperature, the desired product was obtained. (3) Mix polyurea resin and curing agent diethyltoluene diamine (DETDA) evenly at a molar ratio of -NCO to -NH2 of 1.05:1, and then spray the mixture onto the surface and sides of the polyborosiloxane to ensure complete coverage and control the thickness to 0.4 mm. Cure the coated sample at 35°C for 1.5 h, then remove and cool to room temperature; The polyurea resin is a prepolymer of carbodiimide-modified MDI (liquefied MDI) and polyesteramine (PEA-1000), with an -NCO content of 17%.

[0058] Comparative Example 2 (1) Mix the A and B components of Ecoflex 20 evenly in a 1:1 mass ratio, pour into a mold, and remove air bubbles by vacuum drying at 25 °C for 10 min. Then, after curing at 50 °C for 3 h, pour into a mold to obtain a soft elastomer layer with microstructure 1 on the surface, ensuring a layer thickness of 1 mm; (2) 20 g of hydrogen-bonded reinforced polyborosiloxane was coated on the upper surface of the soft elastomer layer and placed in an 80°C oven for 2 h to accelerate its softening and flow until it completely filled the microstructure voids. After cooling to room temperature, excess polyborosiloxane at the edges and top was trimmed with a scraper to ensure a layer thickness of 1 mm; Hydrogen-bonded reinforced polyborosiloxanes were polymerized at 90 °C for 4 h using hydroxyl silicone oil with a molecular weight of 2000 and boric acid in a molar ratio of 2.5:1 to obtain oligomeric borosiloxanes. The polymers were then heated in an open environment for another 2 h to remove moisture. After cooling to room temperature, isophorone diisocyanate (IPDI) (1 / 8 molar of the hydroxyl groups in the oligomeric borosiloxanes) and dibutyltin dilaurate (catalyst) (0.05% by mass of the reactants) were added. The reaction was carried out at 80 °C under a nitrogen atmosphere for 4 h. After cooling to room temperature, the polymer was obtained.

[0059] Comparative Example 3 (1) Mix the A and B components of Ecoflex 20 evenly in a 1:1 mass ratio, pour into a mold, and remove air bubbles by vacuum drying at 25 °C for 10 min. Then, after curing at 50 °C for 3 h, pour into a mold to obtain a soft elastomer layer with microstructure 1 on the surface, ensuring a layer thickness of 1 mm; (3) Mix polyurea resin and curing agent diethyltoluene diamine (DETDA) evenly at a molar ratio of -NCO to -NH2 of 1:1, and then spray the mixture onto the upper surface and sides of the soft elastomer layer to ensure complete coverage and control the thickness in the direction of 1 mm. Cure the coated sample at 35°C for 1.5 h, and then remove it and cool it to room temperature; The polyurea resin is a prepolymer of carbodiimide-modified MDI (liquefied MDI) and polyesteramine (PEA-1000), with an -NCO content of 17%.

[0060] Test case 1. Impact resistance test The samples from Examples 1-3 and Comparative Examples 1-3 were cut into 5×5 cm pieces for impact resistance testing. The hammer head diameter of the drop hammer impact tester was 16 mm. The samples were placed on a flat plate in the impact zone, and the impact energy was set to 15 J. The load-time curves of the three samples during the impact process were obtained (e.g., ...). Figure 4 As shown in the figure), the energy absorption efficiency was calculated and the statistics are shown in Table 1 below.

[0061] Table 1

[0062] As can be seen from Examples 1-3, with the increase of thickness, the peak load of the flexible armor gradually decreases, the contact time is significantly prolonged, and the energy absorption efficiency is significantly improved. According to Example 1 and Comparative Example 1, it was found that the impact resistance of the armor slightly decreased after removing the microstructure (the peak load increased, and both the contact time and energy absorption efficiency decreased). Improving the overall integrity of the armor through microstructure design is beneficial to improving the impact resistance. According to Example 1 and Comparative Examples 2-3, it was found that at the same thickness, the armor containing more polyborosiloxane layers has better impact resistance (Comparative Example 2), but the overall strength is lower, and it is prone to hydrolysis when exposed to air for a long time, which is not conducive to maintaining a stable structure. The armor containing more polyurea layers has a higher peak load and a lower energy absorption rate, and the impact resistance effect is not ideal.

[0063] 2. Self-healing performance test The samples from Examples 1-3 and Comparative Examples 1-3 were cut into rectangular strips of 50 mm × 20 mm × 5 mm, and tensile strength tests were conducted at a tensile rate of 500 mm / min. Self-healing performance was expressed as the recovery rate of tensile strength after 30 min of room temperature repair following cutting, relative to the original tensile strength; that is, the self-healing efficiency was equal to the ratio of the tensile strength after repair to the original tensile strength. The test results are statistically shown in Table 2.

[0064] Table 2

[0065] As can be seen from Examples 1-3, the strength of the material gradually increases with increasing thickness, and the self-healing efficiency improves with increasing thickness of the polyborosiloxane layer and the polyurea layer. According to Example 1 and Comparative Example 1, although the healing efficiency of the flexible armor did not change significantly after removing the microstructure, its strength decreased, mainly due to the lack of mechanical locking. According to Examples 1 and Comparative Examples 2-3, at the same thickness, the overall self-healing efficiency of the flexible armor with the polyborosiloxane layer replacing the polyurea layer (without the polyurea layer) improved, but both its initial strength and post-healing strength were lower. While the flexible armor with the polyurea layer replacing the polyborosiloxane layer (without the polyborosiloxane layer) had high initial strength, its self-healing efficiency and post-healing strength were very low, making it difficult to meet the requirements of emergency protection.

[0066] In summary, optimizing interlayer interface effects through microstructure design is beneficial for improving strength and impact resistance. Furthermore, the synergistic effect of the three-layer structure (soft elastomer layer, polyborosiloxane layer, and polyurea layer) is a key strategy for achieving both superior strength and self-healing efficiency, as well as excellent impact resistance synergistically with strength.

[0067] 3. Applications of soft robots Mix Ecoflex 30 components A and B in a 1:1 mass ratio until homogeneous, pour into a mold, and vacuum-dry at 25°C for 10 minutes to remove air bubbles. Then, after curing at 50°C for 3 hours, cast to obtain a micro-channel driving layer with micro-channels on one side, ensuring a total layer thickness of 4 mm, of which the channel layer thickness is 2 mm (e.g., ...). Figure 5 (As shown).

[0068] The flexible armor prepared in Example 1 was used as the bottom layer of the pneumatic tentacle. It was bonded to the micro-airway driving layer with the adhesive Sil-poxy. The soft elastomer layer of the flexible armor was in contact with the micro-airway driving layer to obtain the flexible armor pneumatic tentacle. A capillary tube was inserted at the end as a channel for air pump inflation.

[0069] Then the five tentacles and Figure 6 The top and bottom layers shown are assembled together to form a pneumatic gripper. The capillary channels in the top layer are responsible for leading out the capillaries connecting the five tentacles. These five capillaries are then integrated at the capillary confluence and led out, subsequently connected to an air pump, thus obtaining a pneumatic gripper with flexible armor (such as...). Figure 7 (As shown).

[0070] During ventilation, due to the stiffness difference between the micro-airway driving layer and the flexible armor layer, the micro-airway driving layer undergoes significant deformation, causing the tentacle to bend towards the flexible armor layer. When driving the pneumatic gripper, the inner side is the polyurea layer of the flexible armor, while the outer side is the micro-airway driving layer. On one hand, the flexible armor's softness meets the large deformation requirements of the pneumatic gripper, ensuring driving flexibility; on the other hand, the flexible armor's excellent protection expands the gripper's application range and extends its service life. For example, when gripping objects with sharp surfaces, even if punctured, it can quickly repair itself thanks to its excellent self-healing properties and continue to be used.

[0071] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. An adaptive, repairable flexible armor, characterized in that, From bottom to top, the layers are: an inner soft elastomer layer, an intermediate impact-hardening layer, and an outer polyurea layer. The soft elastomer layer and the impact hardening layer are connected by a mechanical microstructure; The impact-hardened layer is connected to the polyurea layer on the opposite side from the soft elastomer layer via chemical and hydrogen bonds.

2. The flexible armor according to claim 1, characterized in that, The thickness ratio of the polyurea layer, the impact-hardening layer, and the soft elastomer layer is 1-3:2-4:3-7.

3. The flexible armor according to claim 1, characterized in that, The polyurea layer is formed by curing polyurea resin and a curing agent; the curing conditions are: temperature 30-40 ℃, time 1-2 h.

4. The flexible armor according to claim 3, characterized in that, Polyurea resin is a prepolymer formed by isocyanate and polyetheramine / polyesteramine; the curing agent is an amine compound; the molar ratio of isocyanate in polyurea resin to amine in curing agent is 1.05-1.1:

1.

5. The flexible armor according to claim 1, characterized in that, The material of the impact hardening layer is hydrogen bond-reinforced polyborosiloxane; the hydrogen bond-reinforced polyborosiloxane is prepared by reacting oligomeric borosiloxane with isocyanate under the action of catalyst dibutyltin dilaurate; the reaction conditions are: 70-90 ℃ under nitrogen atmosphere for 3-4 h. Oligomeric borosilicates are prepared by polymerizing hydroxyl silicone oil with boron-containing compounds at 80-90 °C for 4-6 h.

6. The flexible armor according to claim 5, characterized in that, The molar ratio of isocyanate ions to hydroxyl groups in oligomeric borosilicates is 1:4-8; the molar ratio of hydroxyl groups to hydroxyl groups in hydroxyl silicone oils is 2.5-3:

1.

7. The flexible armor according to claim 1, characterized in that, The soft elastomer layer is formed by curing polysiloxane elastomer through a mold, and the Young's modulus of the soft elastomer layer is 0.5-2 MPa; the surface of the soft elastomer layer in contact with the impact hardening layer is provided with a concave-convex microstructure; the shape of the concave-convex microstructure is one or more of the following: triangle, rectangle, and circular serrations. The height of the uneven microstructure accounts for 10-30% of the thickness of the soft elastomer layer.

8. A method for preparing the flexible armor according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Mix the raw materials of each component of the soft elastomer evenly according to the proportion, pour them into the microstructure mold, degas, heat and solidify, and pour the mold to obtain a soft elastomer layer with microstructure on the surface. (2) Hydrogen-bonded polyborosiloxane is coated on the upper surface of the soft elastomer layer, heated to flow, and cooled to room temperature to form an impact-hardened layer; (3) Mix polyurea resin and curing agent evenly according to the ratio, and then spray or scrape it onto the surface and sides of the impact hardening layer, heat to cure, and cool to room temperature to obtain the flexible armor.

9. The preparation method according to claim 8, characterized in that, In step (1), the curing conditions are: 50-60 ℃ for 3-4 h; in step (3), the curing conditions are: 30-40 ℃ for 1-2 h.

10. An application of the flexible armor according to claim 1, characterized in that, Used in the manufacture of personal protective equipment, soft robot protection, flexible electronic protection, and emergency equipment protection products.

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