Polymer interface material and application

Abstract

The invention provides a polymer interface material and application, and relates to the technical field of materials. Specifically, the polymer interface material comprises a skeleton and a grafting group connected to the skeleton through a dynamic covalent bond, the dynamic covalent bond comprises at least one of an ester bond, an imine bond, a trithiocarbonate bond, an alkoxyamine bond, a disulfide bond and a borate bond. According to the material, a dynamic covalent bond which is subjected to a bond exchange reaction or a homocracking / recombination reaction under specific stimulation is introduced into a molecular network, and the dynamic network realizes topological structure reconstruction through bond exchange or recombination, so that high interface strength, high toughness and non-performance vacuum self-repairing capability are synergistically realized, and the material has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and more specifically, to a polymer interface material and its application. Background Technology

[0002] Polymer composites are widely used due to their lightweight and high strength; however, their multiphase interfaces are often weak points in mechanical properties. Current processes often employ reactive compatibilizers to introduce permanent covalent bonds at the interface to improve interfacial bonding. However, despite compatibilizer reinforcement, this often leads to an imbalance between strength and toughness. Specifically, while compatibilizers significantly improve initial bonding strength by introducing permanent covalent bonds at the interface, they also create a brittle interfacial phase with significant stress concentration. Under external loads, this type of brittle interface is highly susceptible to early initiation and propagation of microcracks. These microcracks not only directly weaken the material's fracture toughness and impact resistance but also become potential sources of damage during long-term service. Because traditional interfacial chemical bonds are irreversible, microcracks cannot close spontaneously once formed and are difficult to repair in traditional static interfaces. Damage accumulates over time and with stress cycles, eventually leading to interfacial delamination failure, severely limiting the reliability and service life of composite materials under dynamic loads or long-term service environments.

[0003] To overcome these limitations, existing technologies attempt to endow interfaces with self-healing capabilities. However, such strategies typically face a key challenge: the repair process often relies on the dissociation of interface molecules or significant migration of molecular chains. This inevitably leads to temporary dissociation or softening of the interface structure during the repair process, preventing the material from effectively transferring stress during the repair period and creating a vacuum in load-bearing function. Furthermore, there is often an irreconcilable contradiction between the initial interface strength and high self-healing efficiency; high-strength interfaces usually depend on high cross-linking density or strong forces, implying lower chain segment mobility. This severely limits the movement and diffusion rate of chain segments in the interface region, making molecular recombination necessary for repair difficult and severely restricting repair capabilities. Therefore, how to synergistically optimize interface design to maintain high initial strength while ensuring that the interface possesses rapid, efficient, and partially load-bearing repair capabilities is a key scientific challenge currently facing interface engineering.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a polymer interface material that offers a novel interface design strategy. This strategy not only enhances interface toughness to suppress the initiation of microcracks but also provides a highly efficient repair mechanism without experiencing a performance vacuum after damage occurs, thereby simultaneously achieving high interface strength, high damage tolerance, and long-life reliability.

[0006] A second object of the present invention is to provide a polymer composition.

[0007] A third objective of this invention is to provide a fiber-reinforced composite material.

[0008] A fourth objective of this invention is to provide an article of manufacture.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A polymer interface material includes a backbone and graft groups connected to the backbone via dynamic covalent bonds; The dynamic covalent bond includes at least one of the following: ester bond, imine bond, trithiocarbonate bond, alkoxyamine bond, disulfide bond, and borate ester bond.

[0010] Preferably, the dynamic covalent bond reacts under external influence; The type of reaction includes either a bond exchange reaction or a reversible homolytic cleavage / recombination reaction.

[0011] More preferably, when the dynamic covalent bond is an ester bond, the external action includes either heat or a catalyst; the type of reaction includes a bond exchange reaction. More preferably, when the dynamic covalent bond is an imine bond, the external action includes one of heat, acid catalysis, or water; the type of reaction includes a bond exchange reaction; More preferably, when the dynamic covalent bond is a trithiocarbonate bond, the external action includes either heat or ultraviolet light; the type of reaction includes a bond exchange reaction. More preferably, when the dynamic covalent bond is an alkoxyamine bond, the external action includes either heat or ultraviolet light; the type of reaction includes a reversible homolytic cleavage / recombination reaction; More preferably, when the dynamic covalent bond is a disulfide bond, the external action includes one of heat, ultraviolet light, base catalysis, or a reducing agent; the type of reaction includes one of bond exchange reaction or reversible homolytic cleavage / recombination reaction; More preferably, when the dynamic covalent bond is a borate ester bond, the external action includes one of moisture, heat, or pH change; and the type of reaction includes bond exchange reaction.

[0012] Preferably, the skeleton comprises at least one of polyolefin, polyester, polyamide, polyurethane, polyether, polycarbonate, polyacrylate, polymethacrylate, polystyrene, and copolymers of the above components.

[0013] More preferably, the molar ratio of the dynamic covalent bond to the skeleton is 0.1% to 50%.

[0014] Preferably, the framework includes active functional groups; The active functional group includes at least one of carboxyl, epoxy, amino, hydroxyl, ester, isocyanate, or anhydride groups.

[0015] More preferably, the mass ratio of the active functional group to the polymer interface material is 0.05% to 10%.

[0016] A polymer composition comprising the aforementioned polymer interface material.

[0017] A fiber-reinforced composite material includes a fiber reinforcement, a polymer matrix, and the polymer interface material.

[0018] An article comprising the polymer composition described above, or the fiber-reinforced composite material described above.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention provides a novel polymer interface material; by introducing dynamic covalent bonds at the molecular scale and realizing the reaction under the stimulation of external factors, a topological adaptive network is constructed at the interface of the composite material, thereby synergistically achieving high interface strength, high toughness and self-healing ability without performance vacuum.

[0020] Specifically, the topology adaptive network mechanism of this invention enables the interface network to be reconstructed without breaking the overall connectivity through the exchange or homolytic split-recombination reaction of dynamic bonds. On the one hand, it endows the interface with excellent toughness, effectively dissipating energy through molecular chain slippage, thus exhibiting outstanding toughness. On the other hand, when damaged, the network can complete self-repair while maintaining covalent connections. During the repair process, the network can always maintain basic structural integrity and load-bearing capacity, fundamentally avoiding the mechanical performance vacuum period in traditional repair strategies, thereby simultaneously achieving high initial interface strength and efficient self-repair capability.

[0021] (2) To further achieve the above-mentioned synergistic effect, the polymer interface material of the present invention forms a stable physical or chemical interaction with the surface of the dispersed phase through the active functional groups in its molecular structure, thereby effectively anchoring the dynamic covalent network to the interface of the composite material. This anchoring effect ensures that stress can be efficiently transmitted and dissipated through the dynamic network, which is the structural basis for achieving high strength, high toughness and repairability of the interface. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] A first aspect of the present invention is to provide a polymer interface material comprising a backbone and graft groups attached to the backbone, wherein the two are connected by dynamic covalent bonds; the dynamic covalent bonds include at least one of ester bonds, imine bonds, trithiocarbonate bonds, alkoxyamine bonds, disulfide bonds, and borate ester bonds.

[0024] It is understood that the polymer interface material in this invention includes the dynamic covalent bond, and the dynamic covalent bond can react under external action; and the type of reaction includes one of bond exchange reaction or reversible homolytic cleavage / recombination reaction.

[0025] As a preferred embodiment, the external action includes one or more of thermal energy, light energy, chemical stimulation, and mechanical force; it is understood that the above-mentioned reaction of the dynamic covalent bond in the present invention is dynamically reversible, and one of the above-mentioned reactions can be initiated by one or two of the external actions, thereby realizing the self-healing function of the material.

[0026] As a more preferred implementation, the relationship between the dynamic covalent bond and the external interaction specifically includes: (a) When the dynamic covalent bond is an ester bond, the external action includes either heat or a catalyst; the corresponding reaction type includes bond exchange reaction; (b) When the dynamic covalent bond is an imine bond, the external action includes one of heat, acid catalysis, or water; the corresponding reaction type includes bond exchange reaction; (c) When the dynamic covalent bond is a trithiocarbonate bond, the external action includes either heat or ultraviolet light; the corresponding reaction type includes bond exchange reaction; (d) When the dynamic covalent bond is an alkoxyamine bond, the external action includes either heat or ultraviolet light; the corresponding reaction type includes reversible homolytic cleavage / recombination reaction, specifically, the reaction is the homolytic cleavage and recombination of NO bonds; (e) When the dynamic covalent bond is a disulfide bond, the external action includes one of heat, ultraviolet light, base catalysis or reducing agent; the corresponding reaction type includes bond exchange reaction or reversible homolytic cleavage / recombination reaction; for example, under basic conditions, the disulfide bond can be nucleophilically substituted through a thiolate anionic intermediate to achieve bond exchange; (f) When the dynamic covalent bond is a borate ester bond, the external action includes one of moisture, heat, or pH change; the corresponding reaction type includes bond exchange reaction.

[0027] In a preferred embodiment, the skeleton comprises at least one of polyolefins, polyesters, polyamides, polyurethanes, polyethers, polycarbonates, polyacrylates, polymethacrylates, polystyrene, and copolymers selected above. In some embodiments, the skeleton has a structure including, but not limited to, linear, branched, or lightly crosslinked forms.

[0028] In a preferred embodiment, the molar ratio of the dynamic covalent bond to the skeleton is 0.1% to 50%, including but not limited to any one or any two of the following values: 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%.

[0029] In a preferred embodiment, the skeleton includes active functional groups, that is, the active functional groups are included in the polymer interface material, which can form chemical bonds with the reinforcing body or another polymer phase; in some embodiments, the active functional groups include at least one of carboxyl, epoxy, amino, hydroxyl, ester, isocyanate or anhydride groups.

[0030] In a more preferred embodiment, the mass ratio of the active functional group to the polymer interface material is 0.05% to 10%, including but not limited to any one or any two of the following: 0.05%, 0.1%, 0.2%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 9.5%, and 10%.

[0031] In a more preferred embodiment, the active functional groups can be introduced into the polymer interface material in advance through a chemical reaction from the raw materials of the framework, or they can be introduced through a chemical reaction after the precursor of the polymer interface material is obtained.

[0032] In a preferred embodiment, the polymer interface material is synthesized from the following raw materials: polymer raw materials for the backbone and functional monomer raw materials; it is understood that the functional monomer directly determines the structure of the grafting group; furthermore, the types of raw materials for the functional monomer are selected based on the types of dynamic covalent bonds: (A) When the dynamic covalent bond is an ester bond, the functional monomer includes at least one of the following: compounds containing carboxyl groups or anhydrides (including but not limited to maleic anhydride, acrylic acid, methacrylic acid, succinic anhydride, phthalic anhydride, carboxyl-terminated polybutadiene, etc.); and compounds containing hydroxyl or epoxy groups (including but not limited to glycidyl methacrylate, allyl glycidyl ether, pentaerythritol, polyethylene glycol, 1,4-butanediol, etc.). (B) When the dynamic covalent bond is an imine bond, the functional monomer includes at least one of the following: compounds containing aldehyde or ketone groups (including but not limited to terephthalaldehyde, 1,3,5-tricarboxyphenyl, glyoxal, etc.) and compounds containing amino or hydrazine groups (including but not limited to ethylenediamine, p-phenylenediamine, hexamethylenediamine, polyetheramine, carbazide, etc.); (C) When the dynamic covalent bond is a trithiocarbonate bond, the functional monomer includes compounds containing trithiocarbonate groups (-SC(=S)-S-), including but not limited to S-dodecyl-S'-(α,α'-dimethyl-α''-acetic acid) trithiocarbonate, S,S'-di(α,α'-methyl-α''-acetic acid) trithiocarbonate, S,S-dibenzyl trithiocarbonate, etc.; in some embodiments, the functional monomer is subjected to RAFT polymerization with a polymerizable monomer to prepare a polymer with trithiocarbonate groups in the main chain or at the end; (D) When the dynamic covalent bond is an alkoxyamine bond, the functional monomer includes compounds containing an alkoxyamine structure (NOC), including but not limited to 1-(cyano-1-methylethoxy)-4-methoxy-2,2,6,6-tetramethylpiperidine, CPDMN or TEMPO-derived alkoxyamines, etc. (E) When the dynamic covalent bond is a disulfide bond, the functional monomer includes at least one of the following: compounds containing a disulfide bond (-SS-) (including but not limited to dithiodipropionic acid, cystamine, polyethylene glycol derivatives containing a disulfide bond, etc.) or compounds containing a mercapto group (-SH) (including but not limited to mercaptoacetic acid, 2-mercaptoethanol, 3-mercaptopropionic acid, pentaerythritol tetra(3-mercaptopropionate) etc.); (F) When the dynamic covalent bond is a borate ester bond, the functional monomer includes at least one of the following: compounds containing boric acid or borate ester groups (including but not limited to phenylboronic acid, pinacol borate, 2-hydroxyethylacrylamide pinacol borate, etc.) and compounds containing ortho-diol or polyhydroxyl groups (including but not limited to 1,2-propanediol, polyvinyl alcohol, sugar compounds such as glucose, etc.).

[0033] A second aspect of the present invention is to provide a polymer composition comprising the polymer interface material as described in the first aspect. It is understood that the polymer composition may further comprise one or more of the following: plasticizers (such as phthalates) for increasing flexibility, lubricants (such as stearates) for improving processing flowability, heat stabilizers (such as lead salts, calcium-zinc stabilizers) for preventing thermal degradation during processing, antioxidants (such as hindered phenolic compounds) for inhibiting oxidative aging, light stabilizers for preventing UV degradation, fillers (such as calcium carbonate, carbon black) for reinforcement, weight gain, or conductivity, flame retardants (such as aluminum hydroxide, bromine compounds) for improving fire resistance, colorants (pigments, dyes), etc. Those skilled in the art can make adaptive selections based on the intended use of the polymer composition.

[0034] A third aspect of the present invention is to provide a fiber-reinforced composite material comprising a polymer interface material, a fiber reinforcement, and a polymer matrix as described in the first aspect.

[0035] In one preferred embodiment, the fiber reinforcement includes, but is not limited to, at least one of glass fiber, carbon fiber, aramid fiber, basalt fiber, ultra-high molecular weight polyethylene fiber, boron fiber, silicon carbide fiber, and natural plant fiber. In some embodiments, the fiber morphology of the fiber reinforcement can be chopped fiber, continuous fiber, fiber fabric, or fiber felt, etc.

[0036] In a preferred embodiment, the polymer matrix comprises a thermoplastic resin or a thermosetting resin. In some more preferred embodiments, the thermoplastic resin includes, but is not limited to, at least one of polyolefins (such as polypropylene, polyethylene), polyamides (such as nylon 6, nylon 66), polyesters (such as polyethylene terephthalate, polybutylene terephthalate), polycarbonate, polyetheretherketone, polyphenylene sulfide, polyurethane, and polymethyl methacrylate; the thermosetting resin includes, but is not limited to, at least one of epoxy resins, unsaturated polyester resins, vinyl ester resins, phenolic resins, and bismaleimide resins.

[0037] In a preferred embodiment, the mass ratio of the fiber reinforcement to the polymer matrix is ​​5:95 to 70:30.

[0038] In a preferred embodiment, the amount of polymer interface material added is 0.1% to 20% of the total mass of the fiber-reinforced composite material.

[0039] A fourth aspect of the invention is to provide an article comprising a polymer composition as described in the second aspect, or a fiber-reinforced composite material as described in the third aspect.

[0040] Example 1: Interfacial materials based on dynamic ester bonds and their application in GF / PP composites.

[0041] Under nitrogen protection, 100g of carboxyl-terminated hydrogenated polybutadiene (carboxyl content 0.8mmol / g), 12g of glycidyl methacrylate, and 0.4g of zinc acetylacetonate were stirred and reacted at 130℃ for 4h.

[0042] Fourier transform infrared spectroscopy at 1735 cm⁻¹ -1 The formation of characteristic absorption peaks of ester bonds was confirmed, indicating the successful synthesis of the dynamic ester bond interface material (HPBD-g-Ester). This material was added at 4 wt.% to a composite system of polypropylene and chopped glass fiber (PP / GF, 70 / 30, w / w), and then melt-blended and injection-molded at 190°C using a twin-screw extruder.

[0043] Testing revealed that the initial system of polypropylene and chopped glass fiber without added interface material exhibited a shear strength of 20.5 MPa and a notched impact strength of 18 kJ / m. 2 The fracture morphology exhibits typical brittle fracture characteristics. After adding HPBD-g-Ester, the interlaminar shear strength of the composite material increased to 42.8 MPa, and the notched impact strength significantly improved to 35 kJ / m². 2 The impact fracture surface showed obvious fiber removal and plastic deformation, proving that the interfacial toughness was fundamentally improved.

[0044] Further stress relaxation tests were conducted using dynamic thermomechanical analysis. The characteristic relaxation time (τ*) of the composite material at 130℃ was 450s, and 78% of the initial stress was relaxed within 30min, indicating that the dynamic ester bond network effectively dissipated the interfacial stress through bond exchange.

[0045] Further testing of self-healing performance involved subjecting the specimen to three-point bending pre-damage until the load decreased by 15%, followed by heat treatment at 130℃ for 90 min. After conventional repair, the interlaminar shear strength of the specimen recovered to 39.5 MPa. During the repair process, a constant bending stress of 5 MPa was applied to the specimen, and its creep strain increased by only 0.8% within 2 hours, far below the critical strain at which failure occurred. This demonstrates that the interface network maintained structural integrity during the repair process, successfully avoiding a performance vacuum period.

[0046] Comparative Example 1: Permanent covalent bond interface material (static network).

[0047] Maleic anhydride-grafted polypropylene (grafting rate 0.9%) was prepared and used at 5 wt.% in the same PP / GF system as in Example 1.

[0048] The interlaminar shear strength was tested to be 30.5 MPa, and the notched impact strength was 24 kJ / m. 2 All were significantly lower than in Example 1.

[0049] Further stress relaxation tests revealed that the material only relaxed 15% of its initial stress within 30 minutes at 130°C, indicating a lack of dynamic stress dissipation capability at the interface. After damage treatment, heat treatment at 130°C for 90 minutes did not restore the interlaminar shear strength, and the crack morphology showed no improvement.

[0050] Comparative Example 2: Physical blend system (no chemical bonding).

[0051] The carboxyl-terminated hydrogenated polybutadiene, glycidyl methacrylate and zinc acetylacetonate catalyst used in Example 1 were directly and physically mixed without thermal reaction, and then added to the PP / GF composite material in the same total amount.

[0052] The interlaminar shear strength was tested to be 21.5 MPa, and the notched impact strength was 19 kJ / m. 2 It is comparable to the blank sample.

[0053] Further stress relaxation tests showed that the behavior was similar to that of Comparative Example 1, with a relaxation of about 18% within 30 minutes and no self-healing ability, proving that simple physical mixing cannot construct an effective dynamic interface network.

[0054] Comparative Example 3: Structure lacking strong interfacial anchoring groups.

[0055] The process is essentially the same as in Example 1, but instead of using carboxyl-terminated hydrogenated polybutadiene, unfunctionalized hydrogenated polybutadiene is reacted with glycidyl methacrylate.

[0056] It can be seen that the obtained product lacks carboxyl groups that form a strong interaction with the glass fiber surface. When used in a PP / GF system, its interlaminar shear strength was measured to be only 22.0 MPa, and its notched impact strength was 20 kJ / m². 2 .

[0057] Further stress relaxation tests showed that although the stress relaxation behavior was similar to that of Example 1 at 130°C (70% relaxation within 30 minutes), the initial strength and post-repair strength were both at a low level due to the lack of strong interface anchoring, which could not meet the application requirements.

[0058] Example 2: Interfacial materials based on dynamic imine bonds and their application in CF / EP composites.

[0059] 50 g of polyetheramine (Jeffamine D-400, amine value 0.25 mmol / g) and 10 g of 1,3,5-tris(formylphenoxy)benzene were reacted in tetrahydrofuran at 25 °C for 12 h with stirring. Dynamic imine bonds were formed through Schiff base reaction to obtain a cross-linked network prepolymer (Imine-Network). This prepolymer was prepared into a 5 wt.% ethanol solution as an interface coating treatment solution. Subsequently, carbon fiber cloth that had been vacuum dried at 80 °C was immersed in the treatment solution for 8 minutes to ensure full wetting. After that, it was pulled out at a constant speed of 100 mm / min, dried at 60 °C for 2 hours, and then cured at 80 °C for 1 hour, thereby constructing a stable dynamic imine bond interface layer on the fiber surface.

[0060] Bisphenol A type epoxy resin (E-51) and polyetheramine curing agent (D-230) were mixed at a mass ratio of 100:32 and used as the polymer matrix after degassing. The surface-modified carbon fiber cloth was then laid in unidirectional 0-degree layers, for a total of 8 layers. Resin was injected at 0.3 MPa using a resin transfer molding process, ensuring complete impregnation, followed by curing according to a procedure (80℃ / 2h + 120℃ / 4h) to obtain the carbon fiber / epoxy resin composite material.

[0061] Compared to the uncoated carbon fiber cloth-epoxy resin composite system, the Mode I interlaminar fracture toughness (GIC) of the composite material treated with Imine-Network increased from 320 J / m. 2 Increased to 896J / m 2 The increase reached 180%. Scanning electron microscopy observation of the fracture surface showed that the uncoated sample exhibited a smooth interfacial peeling morphology, while the modified sample showed extensive fiber pull-out and resin plastic deformation, proving that the dynamic imine bond network effectively improved toughness and damage tolerance through interfacial plastic deformation.

[0062] After further treatment at 80℃ and 85% relative humidity for 6 hours, the GIC value of the pre-cracked sample recovered to 88% of its initial value. Real-time dynamic thermomechanical analysis performed during the repair process showed that the material's storage modulus decreased by only 12% under humidity stimulation and recovered rapidly after the repair was completed, demonstrating its ability to avoid performance vacuum.

[0063] Example 3: Interfacial materials based on dynamic trithiocarbonate bonds and their application in PMMA / SiO2 nanocomposites.

[0064] Under nitrogen protection, 20 g of methyl methacrylate, 0.32 g of S-dodecyl-S'-(α,α'-dimethyl-α''-acetic acid) trithiocarbonate, and 6.4 mg of azobisisobutyronitrile were dissolved in 40 mL of 1,4-dioxane and reacted at 65 °C for 18 h. After the reaction was completed, the mixture was precipitated in 400 mL of cold methanol, filtered, and vacuum dried for 24 h to obtain a polymethyl methacrylate macromolecular chain transfer agent (PMMA-CTA, number average molecular weight Mn = 24000 g / mol) with trithiocarbonate groups at the ends.

[0065] The PMMA-CTA was used as an interface modifier at 2 wt.% and combined with 10 wt.% of untreated silica nanoparticles (average particle size 50 nm) and polymethyl methacrylate to prepare a composite material by solution blending-casting film formation.

[0066] The polymethyl methacrylate-silica sample without interface modifier exhibited a tensile strength of 48 MPa and an elongation at break of only 4.5% due to severe nanoparticle aggregation. After adding PMMA-CTA, the tensile strength of the composite material increased to 62 MPa, and the elongation at break significantly improved to 32%, demonstrating that the trithiocarbonate bond interface layer promoted stress transfer and plastic deformation through dynamic exchange.

[0067] Further stress relaxation tests showed that the material had a characteristic relaxation time (τ*) of 280 s at 120 °C, and 85% of the initial stress was relaxed within 30 min. After notching the sample, the stress was measured under 365 nm ultraviolet light (100 mW / cm²). 2 After irradiation for 60 minutes, the tensile strength recovered from 35 MPa after damage to 55 MPa, with a recovery rate of 88.7%.

[0068] Example 4: Interface materials based on dynamic alkoxyamine bonds and their application in self-healing coatings.

[0069] 20g of methyl methacrylate, 2g of glycidyl methacrylate, 0.35g of S-dodecyl-S'-(α,α'-dimethyl-α''-acetic acid) trithiocarbonate, and 7mg of azobisisobutyronitrile were subjected to RAFT polymerization according to the method in Example 3 to obtain epoxy-functionalized PMMA (epoxy value 0.18 mmol / g). 5g of this polymer was reacted with 0.85g of 1-(cyano-1-methylethoxy)-4-methoxy-2,2,6,6-tetramethylpiperidine at 60°C for 24h, thereby incorporating an alkoxyamine structure into the polymer side chain through epoxy ring-opening to obtain epoxy-functionalized PMMA-alkoxyamine.

[0070] PMMA-alkoxyamine was formulated into a 20 wt% toluene solution, and a coating with a thickness of approximately 50 μm was prepared by spin coating. Nano-scratch testing showed that the coating exhibited no significant crack propagation at the scratch edges, and the critical scratch load was increased by 60% compared to the unmodified PMMA coating. Furthermore, after creating scratches with a depth of approximately 15 μm on the coating, the coating was tested under 365 nm ultraviolet light (50 mW / cm²). 2 After 30 minutes of irradiation, the scratch width recovered to within 2 μm. Furthermore, the pencil hardness of the repaired coating recovered from 4B to 2H, and its scratch resistance recovered to 90% of its initial state. Additionally, applying a constant load of 5 mN to the coating area during the repair process did not significantly change the scratch depth, demonstrating that the dynamic network effectively protected the substrate under light stimulation.

[0071] Example 5: Verification of interface materials based on dynamic borate ester bonds and their humidity-responsive self-healing mechanism.

[0072] 100g of ethylene-acrylic acid copolymer (acrylic acid content 6wt.%), 12g of 2-hydroxyethylacrylamide borate pinacol ester, and 0.3g of p-toluenesulfonic acid were reactively extruded in a twin-screw extruder at 150°C to prepare an interface material (EAA-Borate) containing dynamic borate ester bonds, which was then used as a compatibilizer.

[0073] The formation of the characteristic peak of the borate ester bond was confirmed at 7.8 ppm by proton nuclear magnetic resonance spectroscopy.

[0074] The compatibilizer was applied at 3 wt.% to a composite system of polypropylene and wood flour (60 / 35, w / w). The polypropylene-wood flour sample without the compatibilizer exhibited a flexural strength of 32 MPa and a notched impact strength of 3.1 kJ / m². 2 The addition of EAA-Borate increased the composite material's flexural strength to 51 MPa and notched impact strength to 5.9 kJ / m². 2 The increase reached 90%.

[0075] Further dynamic thermomechanical analysis showed that in an environment with 85% relative humidity, the material's loss factor (tanδ) increased from 0.12 to 0.28, indicating that the borate ester bonds underwent an exchange reaction under humidity stimulation, effectively dissipating mechanical energy.

[0076] After further three-point bending pre-damage to the specimen, it was placed in an environment with 85% relative humidity for 24 hours, and its bending strength recovered to 46 MPa, with a recovery rate of over 90%. During the repair process, a constant bending stress of 3 MPa was applied to the specimen, and its strain increment was less than 1%, proving that the interface network still maintains its load-bearing capacity when humidity-triggered repair is performed.

[0077] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A polymeric interfacial material, characterized in that, The polymer interfacial material comprises a backbone and grafting groups connected to the backbone via dynamic covalent bonds; The dynamic covalent bonds comprise at least one of ester bond, imine bond, trithiocarbonate bond, alkoxamine bond, disulfide bond, boronate ester bond.

2. The polymeric interfacial material of claim 1, wherein, The dynamic covalent bonds react under external action; The type of reaction comprises bond exchange reaction, or one of homolysis reaction or recombination reaction.

3. The polymeric interfacial material of claim 2, wherein, One or more of the following features (a)~(f) are included: (a) When the dynamic covalent bond is ester bond, the external action comprises one of heat or catalyst; the type of reaction comprises bond exchange reaction; (b) When the dynamic covalent bond is imine bond, the external action comprises one of heat, acid catalysis or water; the type of reaction comprises bond exchange reaction; (c) When the dynamic covalent bond is trithiocarbonate bond, the external action comprises one of heat or ultraviolet light; the type of reaction comprises bond exchange reaction; (d) When the dynamic covalent bond is alkoxamine bond, the external action comprises one of heat or ultraviolet light; the type of reaction comprises one of homolysis reaction or recombination reaction; (e) When the dynamic covalent bond is disulfide bond, the external action comprises one of heat, ultraviolet light, base catalysis or reducing agent; the type of reaction comprises bond exchange reaction, or one of homolysis reaction or recombination reaction; (f) When the dynamic covalent bond is boronate ester bond, the external action comprises one of moisture, heat, pH change; the type of reaction comprises bond exchange reaction.

4. The polymeric interfacial material of claim 1, wherein, The backbone comprises at least one of polyolefin, polyester, polyamide, polyurethane, polyether, polycarbonate, polyacrylate, polymethacrylate, polystyrene, and copolymer of the above components.

5. The polymeric interfacial material of claim 1, wherein, The molar ratio of the dynamic covalent bonds to the backbone is 0.1%~50%.

6. The polymeric interfacial material of claim 1, wherein, The backbone comprises active functional groups; The active functional groups comprise at least one of carboxyl, epoxy, amino, hydroxyl, ester, isocyanate or anhydride.

7. The polymeric interfacial material of claim 6, wherein, The mass ratio of the active functional groups to the polymer interfacial material is 0.05%~10%.

8. A polymer composition, characterized in that, The polymer interfacial material of any one of claims 1~7 is included.

9. A fiber-reinforced composite material, characterized by, The fiber reinforced composite material of claim 9 is included.

10. An article of manufacture characterized by, ​