High-adhesion, low-modulus and high-damping polymer reversible interlocking network adhesive film as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, relates to the technical field of adhesives, and particularly relates to a high-adhesion, low-modulus and high-damping polymer reversible interlocking network adhesive film as well as a preparation method and application thereof. The polymer reversible interlocking network adhesive film provided by the invention comprises a strong bonding single network A containing a dynamic covalent bond and a low modulus single network B containing a dynamic covalent bond. Wherein a polar group in the strong adhesion single network A endows an adhesion interface with adhesiveness, a low-modulus monomer introduced into the low-modulus single network B enables the adhesive to present lower modulus, and an interlocking network structure endows the adhesive with higher cohesiveness and interface adhesion performance. Meanwhile, the adhesive is endowed with the high damping characteristic through slippage and other motions among molecular chains of the interlocking network, and the adhesive film can be endowed with self-repairing performance and recoverability through dynamic bonds in the polymer reversible interlocking network adhesive film. Therefore, the reversible interlocking network adhesive film provided by the invention synergistically realizes three key performances of strong adhesion, low modulus and high damping.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials and the technical field of adhesives, and specifically relates to a polymer reversible interlocking network film with strong adhesion, low modulus and high damping, and a preparation method and application thereof. Background Art

[0002] With the dwindling availability of fossil fuels, environmentally friendly new energy sources are attracting increasing attention. Against this backdrop, the development of new energy vehicles has become a key component in adjusting the energy mix. New energy vehicles, powered by electrochemical powertrains, are gradually replacing traditional fuel-powered vehicles. For new energy vehicles, power batteries, as their core component, are closely linked to vehicle performance. In the early days of new energy vehicle development, power batteries were assembled from multiple cells into modules, which were then secured to a housing to form a battery pack. Modules were primarily connected using traditional mechanical fasteners. However, with the increasing demand for lightweighting, modules have gradually shifted from being a necessary component to becoming a hindrance to technological development. Consequently, current power batteries have evolved to be assembled directly from cells into battery packs. This simplified design avoids the complex module assembly process, improves battery pack volume utilization, reduces overall weight, and ultimately promotes optimized battery performance. Because this new battery pack utilizes direct cell assembly, it relies heavily on adhesives to secure and connect the cell structure. Therefore, the performance of the power battery structural adhesive is crucial to the performance of the battery and, ultimately, the vehicle as a whole.

[0003] In the application of traditional power battery adhesives, bond strength is a core performance indicator. Its importance lies in two aspects: first, the adhesive needs to have strong interfacial adhesion to the substrate, thus forming a stable connection at the interface; second, the adhesive itself needs to have high cohesion to ensure the stability of the overall bonded structure. However, high-strength materials generally exhibit hard and strong properties, while low-modulus materials tend to be soft and tough or soft and weak. In the adhesive field, adhesives with high cohesion generally have higher modulus, but power batteries are often exposed to complex and changing dynamic environments such as vibration during use. High-modulus adhesives cannot effectively absorb stress through damping, which can lead to cracking and failure of the entire bonding system, thus failing to meet the long-term stable operation requirements of power batteries. For these reasons, achieving low modulus while maintaining strong bonding performance is extremely challenging, and there is an inherent contradiction between strength and softness. Therefore, how to design a soft and strong adhesive material has become a key difficulty and technical bottleneck facing the current power battery structural adhesive.

[0004] Chinese invention patent CN 201810866569.4 discloses a method for preparing a dynamic topological interlocking double network. This method designs two cross-linked single networks containing orthogonal dynamic bonds, and uses the exchange / opening of dynamic bonds to achieve full mixing of the two single networks. The uniformly mixed structure is then fixed by the reformation of dynamic bonds, thereby forming a polymer reversible interlocking network, which provides a new idea for achieving uniform mixing at the molecular level between different networks. Chinese invention patent 202211037044.2 achieves strong adhesion between hydrophilic substrates and hydrophobic substrates by adopting a reversible interlocking network method. These results show that the polymer reversible interlocking network provides a new method for integrating multiple contradictory properties. However, the application of this technology in the field of power battery structural adhesives is still in a blank state and urgently needs further exploration and development. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the present invention makes full use of the property of the interlocking network to achieve uniform blending of different materials, designs single networks for providing high bonding strength and low modulus respectively, and then combines the two in the form of a reversible interlocking network, thereby preparing a strong adhesion, low modulus, and high damping polymer reversible interlocking network adhesive film, which provides a new solution for the stable application of power battery structural adhesives under various complex working conditions.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a polymer reversibly interlocked network film with strong adhesion, low modulus, and high damping. The polymer reversibly interlocked network film comprises, by weight percentage, 50%-91% of a strongly adhesive single network A containing dynamic covalent bonds and 9%-50% of a low modulus single network B containing dynamic covalent bonds;

[0008] The strong bonding single network A comprises the following raw materials in parts by weight: 20-30 parts of diisocyanate monomer, 40-55 parts of diol monomer, 15-30 parts of dynamic covalent bond monomer, 0.5-5 parts of adhesive functional monomer, and 0.5-3 parts of crosslinking agent monomer;

[0009] The low modulus single network B comprises the following raw materials in parts by weight: 30-50 parts of diisocyanate monomer, 40-60 parts of diol monomer, 10-20 parts of dynamic covalent bond monomer, 5-10 parts of damping monomer, and 10-30 parts of crosslinking agent monomer.

[0010] The present invention is based on the polymer network film structure of the reversible interlocking network, and organically combines a strong bonding single network and a low modulus single network in the form of a reversible interlocking network. Among them, the strong bonding single network constructs an effective bonding force on the surface of the substrate, while the low modulus single network is conducive to reducing the modulus of the interlocking network and accelerating stress relaxation. At the same time, due to the unique structure of the reversible interlocking network, the adhesive has good energy dissipation capacity, thereby showing high damping characteristics. Therefore, the present invention successfully prepared a strong bonding, low modulus, high damping polymer reversible interlocking network film by combining a strong bonding single network and a low modulus single network in the form of a reversible interlocking network. The film not only shows a good bonding effect on the substrate, but also, by virtue of its low modulus characteristics, can effectively relieve stress concentration by stress relaxation under dynamic conditions, thereby ensuring the stability of the bonding. In addition, the high damping characteristics of the adhesive as a whole can absorb energy and reduce shock by efficiently dissipating energy, thereby providing a solid guarantee for the bonding reliability under dynamic load conditions. In summary, the adhesive film prepared by the present invention effectively solves the contradictory dilemma faced by existing adhesive films between strong adhesion, low modulus and high damping, and synergistically achieves these three properties, providing a new solution for the stable application of adhesives in various complex working conditions.

[0011] Preferably, in the strong bonding single network A, the diisocyanate monomer is at least one of isophorone diisocyanate (CAS No.: 4098-71-9), toluene diisocyanate (CAS No.: 26471-62-5), diphenylmethane diisocyanate (CAS No.: 101-68-8), o-phthalimethylene diisocyanate (CAS No.: 25854-16-4), and hexamethylene diisocyanate (CAS No.: 822-06-0); the diol monomer is polyethylene glycol (CAS No.: 101-68-8). No.: 25322-68-3), polytetramethylene glycol (CAS No.: 25190-06-1), polypropylene glycol (CAS No.: 25322-69-4), polycaprolactone diol (CAS No.: 36890-68-3), polylactic acid diol (CAS No.: 26780-50-7), polycarbonate diol (CAS No.: 29862-10-0); the dynamic covalent bond monomer is a dihydroxy-terminated borate monomer (its structure and preparation refer to the literature "Song K, Ye W, Gao X, Fang H, Zhang Y, Zhang Q, Li X, Yang S, Wei H, Ding Y. Synergy between dynamic covalent boronic ester and boron-nitrogen coordination: strategy for self-healing polyurethane elastomers at room temperature with unprecedented mechanical properties. Materials Horizons, 2021, 8, 216.), double-bond-terminated boronate monomers (their structures and preparations refer to “Cash JJ, Kubo T, Bapat AP, Sumerlin BS. Room-temperature self-healing polymers based on dynamic-covalent boronic esters. Macromolecules, 2015, 48, 2098-2106.”), diol monomers containing Schiff base bonds (their structures and preparations refer to “Arivalagan V, Devaraj Stephen L, Meera M, Gunasekaran SG.Carbazole-terminal phenylene core imine skeletal nanosilica reinforced polybenzoxazine (nSiO2 / PBZ) hybrid nanocomposites. Journal of Polymer Research, 2021, 28, 381. The adhesive functional monomer is at least one of 3,5-dihydroxybenzonitrile (CAS No.: 19179-36-3), 2,3-dihydroxypropionic acid (CAS No.: 473-81-4), dihydroxymaleic acid (CAS No.: 526-84-1), and dimethylolpropionic acid (CAS No.: 4767-03-7). The crosslinker monomer is at least one of triethanolamine (CAS No.: 102-71-6), glycerol (CAS No.: 56-81-5), and diethylenetriamine (CAS No.: 111-40-0).

[0012] Preferably, in the low modulus single network B, the diisocyanate monomer is at least one of isophorone diisocyanate (CAS No.: 4098-71-9), toluene diisocyanate (CAS No.: 26471-62-5), diphenylmethane diisocyanate (CAS No.: 101-68-8), o-phthalimethylene diisocyanate (CAS No.: 25854-16-4), and hexamethylene diisocyanate (CAS No.: 822-06-0); the diol monomer is polyethylene glycol. At least one of alcohol (CAS No.: 25322-68-3), polytetramethylene glycol (CAS No.: 25190-06-1), polypropylene glycol (CAS No.: 25322-69-4), polycaprolactone diol (CAS No.: 36890-68-3), polylactic acid diol (CAS No.: 26780-50-7), and polycarbonate diol (CAS No.: 29862-10-0); the dynamic covalent bond monomer is 4,4'-dithiodiphenylamine (CAS No. : 722-27-0), 2,2'-diaminodiphenyl disulfide (CAS No.: 1141-88-4), 2-hydroxyethyl disulfide (CAS No.: 1892-29-1), bis(4-aminophenyl) diselenide (CAS No.: 35507-35-8); the damping monomer is diethyl bis(hydroxymethyl)malonate (CAS No.: 20605-01-0), N,N-dimethyl-N',N'-bis(2-hydroxypropyl)-1,3-propylenediamine (CAS No.: The cross-linking agent monomer is at least one of melamine-amide (CAS No.: 645-93-2), polyether triol (CAS No.: 9003-11-6), triethanolamine (CAS No.: 102-71-6), glycerol (CAS No.: 56-81-5), and diethylenetriamine (CAS No.: 111-40-0).

[0013] Preferably, the preparation method of the strong bonding single network A is: dissolving the diol monomer and the diisocyanate monomer in an organic solvent, reacting at 50-70°C for 10-15 hours, then adding the dynamic covalent bond monomer, the bonding functional monomer and the organic solvent, continuing the reaction for 10-15 hours after dissolution, and finally adding the crosslinker monomer, continuing the reaction for 10-15 hours after dissolution, and drying after the reaction.

[0014] Preferably, the preparation method of the low modulus single network B is: dissolving a diol monomer and a diisocyanate monomer in an organic solvent, reacting at 50-70°C for 10-15 hours, then adding a damping monomer, a dynamic covalent bond monomer and an organic solvent, continuing the reaction for 10-15 hours, and finally adding a cross-linking agent, continuing the reaction for 10-15 hours, and drying after the reaction.

[0015] The polymer reversible interlocking network film provided by the present invention includes a strong bonding single network A containing dynamic covalent bonds and a low modulus single network B containing dynamic covalent bonds. Among them, the polar group in the strong bonding single network A gives the adhesion of the bonding interface, and the low modulus monomer introduced in the low modulus single network B makes it present a lower modulus, and the interlocking network structure makes the network load-bearing uniform, thereby giving the adhesive a stronger cohesiveness and interface adhesion performance. At the same time, the excellent dissipative performance brought about by the movement such as slip between the interlocking network molecular chains gives the adhesive high damping characteristics, so that it can reduce vibration by efficient dissipation, thereby protecting the bonding effect. Therefore, the present invention, on the basis of ensuring bonding strength, simultaneously gives the adhesive low modulus and high damping performance, thereby realizing protection of the bonding structure, so that it can still maintain a stable bonding effect under various dynamic load service conditions. In addition, the dynamic bonds in the polymer reversible interlocking network film can also give the film self-repairing and recyclability.

[0016] More preferably, the organic solvent includes at least one of N,N-dimethylformamide, tetrahydrofuran, and dichloromethane.

[0017] The second aspect of the present invention provides a method for preparing the polymer reversibly interlocked network film with strong adhesion, low modulus, and high damping according to the first aspect, comprising the following steps:

[0018] S1. crushing a strong adhesive single network A containing dynamic covalent bonds and a low modulus single network B containing dynamic covalent bonds, respectively, and swelling them in an organic solvent, and mixing them to obtain solutions A and B;

[0019] S2. Mix solution A and solution B at 80° C.-130° C. in an inert gas atmosphere, remove most of the solvent, and then dry to obtain the product.

[0020] Preferably, the organic solvent includes at least one of N,N-dimethylformamide, tetrahydrofuran, and dichloromethane.

[0021] Preferably, the swelling is performed at room temperature for 1-3 hours.

[0022] Preferably, the drying temperature is 60-100° C., and the drying is performed to a constant weight.

[0023] The third aspect of the present invention provides the use of the strong adhesion, low modulus, high damping polymer reversible interlocking network film described in the second aspect in power battery structural adhesive.

[0024] The present invention combines a strong bonding single network and a low modulus single network in the form of a reversible interlocking network, thereby preparing a polymer reversible interlocking network adhesive film with strong bonding, low modulus, and high damping. This adhesive film not only has high bonding strength to the substrate, but also, due to its low modulus and high damping properties, can ensure the stability of the bonding effect under various conditions through stress relaxation and vibration reduction. In summary, the adhesive film prepared by the present invention solves the dilemma faced by existing adhesive films between strong bonding and low modulus, and synergistically achieves the three key properties of strong bonding, low modulus, and high damping, thereby facilitating the stable operation of the adhesive structure and extending its service life.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention discloses a novel method for preparing a reversibly interlocked polymer network film. First, a cross-linked polyurethane single network containing dynamic covalent bonds with good bonding properties and a cross-linked polyurethane single network containing dynamic covalent bonds with low modulus are designed, and then the two single networks are prepared into the form of a reversible interlocked network. Not only is a strong bonding effect on the substrate achieved through the interfacial adhesion of the bonding single network and the cohesion of the interlocking network, but the introduction of the low-modulus single network can also adjust the modulus of the interlocking network to exhibit a lower modulus characteristic, so that the prepared adhesive material can avoid stress damage through stress relaxation under dynamic conditions, thereby ensuring the integrity of the adhesive and the final bonding effect. At the same time, the unique structure of the interlocking network also gives it high damping properties, so that the adhesive can efficiently dissipate energy, thereby reducing the impact of vibration and ensuring that the bonding effect is not destroyed. Therefore, by introducing a reversibly interlocking network structure, the present invention blends a strong bonding network with a low-modulus network, effectively resolving the conflicting demands of strong bonding, low modulus, and high damping faced by power battery structural adhesives. This synergistically achieves these three key performance characteristics, providing a new technical solution and practical reference for the stable application of adhesives in various complex working conditions. Furthermore, the dynamic covalent bonds in the reversibly interlocking polymer network film promote its recycling and self-repair, thereby giving the film higher utilization and a longer service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The free volume and free volume fraction distribution diagrams of the reversibly interlocked network with different single network ratios;

[0028] Figure 2 This is the temperature sweep modulus change diagram of polymer film RILNs under shear mode;

[0029] Figure 3 is the stress-strain curve of polymer film RILNs under tensile mode;

[0030] Figure 4 The strain scanning diagram of polymer film RILNs at different frequencies;

[0031] Figure 5 This is a scratch repair experiment of polymer film RILNs;

[0032] Figure 6 This is the solvent recovery experiment of polymer film RILNs. DETAILED DESCRIPTION

[0033] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0034] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0035] This invention proposes a novel method for preparing a reversibly interlocked polymer network adhesive film. First, a single network with strong adhesion and a single network with low modulus are designed separately. These two networks are then combined to form a reversibly interlocked network. This method leverages the interfacial adhesion and low-modulus, fast stress relaxation properties of the single networks while also imparting excellent cohesive strength and high damping properties through the uniform structure of the reversibly interlocked network. This method successfully overcomes the limitations of traditional adhesives, which struggle to balance these properties. The film prepared using this method simultaneously exhibits the multiple advantages of strong adhesion, low modulus, and high damping, enabling it to exhibit excellent and stable bonding under a variety of complex conditions.

[0036] The bonding units in the strong bonding single network provide good interfacial bonding forces and a certain degree of cohesive bonding strength; while the low modulus single network reduces the overall modulus, allowing the adhesive to maintain a certain degree of softness and rapid stress relaxation behavior under dynamic load conditions such as vibration, thereby effectively avoiding the problem of bonding failure caused by stress concentration. When the two single networks are prepared into an interlocking network, the unique topological interlocking structure further enhances the overall cohesive strength of the adhesive, thereby enhancing the ultimate bonding strength; and the rich microscopic motion mechanisms such as interchain molecular slip introduced by the interlocking structure give the adhesive high damping properties. Under dynamic loads, these molecular motions can absorb energy and dissipate it through internal friction, thereby effectively reducing the vibration amplitude, reducing the impact and damage of vibration on the bonding interface, and enhancing the bonding effect under dynamic load conditions. Therefore, the use of an interlocking network approach can cleverly resolve the contradiction between incompatibility between bonding strength and modulus, successfully achieving an organic fusion of the three properties of strong bonding, low modulus, and high damping, allowing the adhesive to maintain long-lasting and reliable bonding strength even under complex conditions such as repeated bending and vibration.

[0037] To achieve this objective, the present invention introduces an adhesive monomer capable of forming an adhesive force with the substrate surface based on chemical bonds and bonding mechanisms to prepare an adhesive single network. Low-modulus monomers are then prepared by designing pendant chain structures and adjusting crosslink density. Reversible interlocking networks of varying ratios of the adhesive single network and the low-modulus single network are then prepared. Testing and analysis of their bonding, modulus, and damping properties confirm that the present invention achieves an organic and synergistic balance of the three key properties of strong adhesion, low modulus, and high damping, providing new insights for optimizing and improving structural adhesives for power batteries.

[0038] In order to comprehensively and clearly present the technical solutions and significant advantages of the present invention, the present invention is described in detail below in conjunction with specific embodiments.

[0039] Example 1: A strong bonding single network BPU1 containing dynamic covalent bonds

[0040] The preparation method of the strong bonding single network BPU1 containing dynamic covalent bonds is as follows:

[0041] 5 g of polyethylene glycol (CAS No.: 25322-68-3) and 3.11 g of isophorone diisocyanate (CAS No.: 4098-71-9) were dissolved in 20 mL of N,N-dimethylformamide, and the resulting solution was added to a three-necked flask equipped with an argon gas protection device and reacted at 60°C for 12 h. Then, 2.72 g of a dihydroxy-terminated borate monomer (its structure and preparation refer to "Song K, Ye W, Gao X, Fang H, Zhang Y, Zhang Q, Li X, Yang S, Wei H, Ding Y. Synergy between dynamic covalent boronic ester and boron–nitrogen coordination: strategy for self-healing polyurethane elastomers at room temperature with unprecedented mechanical properties. Materials) was added. Horizons, 2021, 8, 216. ), 0.092 g of dimethylolpropionic acid (CAS No.: 4767-03-7) and 15 mL of N,N-dimethylformamide were dissolved and the reaction continued for 12 hours. Finally, 0.149 g of triethanolamine (CAS No.: 102-71-6) was added and dissolved and the reaction continued for 12 hours. After the reaction, the mixture was poured into a mold to form a film (film thickness of approximately 0.8 mm). The resulting film sample was then placed in a 60°C oven and dried to constant weight to obtain a strongly bonded single network BPU1 containing dynamic covalent bonds.

[0042] Example 2: A strong bonding single network BPU2 containing dynamic covalent bonds

[0043] The preparation method of the strong bonding single network BPU2 containing dynamic covalent bonds is as follows:

[0044] 5 g of polycaprolactone diol (CAS No.: 36890-68-3) and 4.20 g of diphenylmethane diisocyanate (CAS No.: 101-68-8) were dissolved in 15 mL of N,N-dimethylformamide, and then the resulting solution was added to a three-necked flask equipped with an argon gas protection device and reacted at 60°C for 12 h; then 2.37 g of a diol monomer containing a Schiff base bond (its structure and preparation refer to "Arivalagan V, Devaraj Stephen L, Meera M, Gunasekaran SG. Carbazole terminal phenylene core imine skeletal nanosilica reinforced polybenzoxazine (nSiO2 / PBZ) hybrid nanocomposites. Journal of Polymer Research, 2021, 28, 381."), 0.5g of 3,5-dihydroxybenzonitrile (CAS No.: 19179-36-3) and 5mL of N,N-dimethylformamide were dissolved and continued to react for 12h; finally, 0.092g of glycerol (CAS No.: 56-81-5) was added and dissolved and continued to react for 12h. After the reaction, the mixture was poured into a mold to form a film (the film thickness was about 0.8mm), and then the obtained film sample was placed in a 60°C oven and dried to constant weight to obtain a strongly bonded single network BPU2 containing dynamic covalent bonds.

[0045] Example 3: A low modulus single network SPU1 containing dynamic covalent bonds

[0046] The preparation method of the low modulus single network SPU1 containing dynamic covalent bonds is as follows:

[0047] 5 g of polylactic acid diol and 2.71 g of hexamethylene diisocyanate (CAS No.: 822-06-0) were dissolved in 10 mL of N, N-dimethylformamide, and the resulting solution was added to a three-necked flask equipped with an argon gas protection device and reacted at 60° C. for 12 hours; then 0.76 g of 2-(pyridin-4-yl)-1,3-propanediol (CAS No.: 102877-55-4), 1.72 g of 4,4'-dithiodiphenylamine (CAS No.: 722-27-0) and 5 mL of N, N-dimethylformamide were added, and the reaction was continued for 12 hours after dissolution; finally, 2 g of polyether triol (CAS No.: 9003-11-6) was added, and the reaction was continued for 12 hours after dissolution. After the reaction is completed, the mixture is poured into a mold to form a film (the film thickness is about 0.8 mm), and then the obtained film sample is placed in a 60°C oven and dried to constant weight to obtain a low-modulus single network SPU1 containing dynamic covalent bonds.

[0048] Example 4: A low modulus single network SPU2 containing dynamic covalent bonds

[0049] The preparation method of the low modulus single network SPU2 containing dynamic covalent bonds is as follows:

[0050] 5 g of polytetrahydrofuran diol (CAS No.: 25190-06-1) and 4.20 g of diphenylmethane diisocyanate (CAS No.: 101-68-8) were dissolved in 20 mL of N,N-dimethylformamide, and the resulting solution was added to a three-necked flask equipped with an argon gas protection device and reacted at 60°C for 12 hours. Then, 1.09 g of N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propylenediamine (CAS No.: 63469-23-8), 1.72 g of 2,2'-diaminodiphenyl disulfide (CAS No.: 1141-88-4) and 10 mL of N,N-dimethylformamide were added, and the reaction was continued for 12 hours after dissolution. Finally, 3 g of melamine-amide (CAS No.: 645-93-2) was added, and the reaction was continued for 12 hours after dissolution. After the reaction is completed, the mixture is poured into a mold to form a film (the film thickness is about 0.8 mm), and then the obtained film sample is placed in a 60°C oven and dried to constant weight to obtain a low-modulus single network SPU2 containing dynamic covalent bonds.

[0051] Example 5: A polymer reversible interlocking network film RILNs11 with strong adhesion, low modulus, and high damping properties

[0052] The polymer reversible interlocking network film RILNs11 with strong adhesion, low modulus and high damping properties contains the following components in parts by weight: 50 parts of a strong adhesion single network BPU1 containing dynamic covalent bonds and 50 parts of a low modulus single network SPU1 containing dynamic covalent bonds.

[0053] The preparation method of the polymer reversible interlocking network film RILNs11 having strong adhesion, low modulus, and high damping properties is as follows:

[0054] (1) 5 g of BPU1 obtained in Example 1 was crushed and swollen in 50 mL of N,N-dimethylformamide and a small amount of water (5 mL) at room temperature for 2 h. The mixture was then vigorously stirred at 80°C under argon protection for 60 min to obtain a colorless transparent solution.

[0055] (2) 5 g of SPU2 obtained in Example 4 was crushed and swelled in 50 mL of N,N-dimethylformamide at room temperature for 1 h, and then vigorously stirred at 80°C under argon protection for 30 min to obtain a yellow clear solution;

[0056] (3) The colorless transparent solution of step (1) and the yellow clear solution of step (2) were mixed, stirred at 100°C under argon protection for 40 minutes, and most of the solvent was removed by rotary evaporation. The mixture was then placed in an oven at 80°C and dried to constant weight to obtain a polymer reversible interlocking network film RILNs11.

[0057] Example 6: A polymer reversible interlocking network film RILNs21 with strong adhesion, low modulus, and high damping properties

[0058] The polymer reversible interlocking network film RILNs21 with strong adhesion, low modulus and high damping properties comprises the following components in parts by weight: 66.66 parts of a strong adhesion single network BPU1 containing dynamic covalent bonds, and 33.33 parts of a low modulus single network SPU1 containing dynamic covalent bonds;

[0059] The preparation method of the polymer reversible interlocking network film RILNs21 with strong adhesion, low modulus and high damping properties is as follows:

[0060] (1) 6.66 g of BPU1 obtained in Example 1 was crushed and swelled in 66 mL of N,N-dimethylformamide and a small amount of water (6.6 mL) at room temperature for 1 h. The mixture was then vigorously stirred at 60°C under argon protection for 70 min to obtain a colorless transparent solution.

[0061] (2) 3.36 g of SPU1 obtained in Example 3 was crushed and swelled in 34 mL of N,N-dimethylformamide at room temperature for 1 h. The mixture was then vigorously stirred at 70°C under argon protection for 30 min to obtain a yellow clear solution.

[0062] (3) The colorless transparent solution of step (1) and the yellow clear solution of step (2) were mixed, stirred at 100°C under argon protection for 40 minutes, and most of the solvent was removed by rotary evaporation. The mixture was then placed in an oven at 80°C and dried to constant weight to obtain a polymer reversible interlocking network film RILNs21.

[0063] Example 7: A polymer reversible interlocking network film RILNs31 with strong adhesion, low modulus, and high damping properties

[0064] The polymer reversible interlocking network film RILNs31 with strong adhesion, low modulus and high damping properties comprises the following components in parts by weight: 75 parts of a strong adhesion single network BPU2 containing dynamic covalent bonds and 25 parts of a low modulus single network SPU1 containing dynamic covalent bonds.

[0065] The preparation method of the polymer reversible interlocking network film RILNs31 having strong adhesion, low modulus, and high damping properties is as follows:

[0066] (1) 7.5 g of BPU2 obtained in Example 2 was crushed and swelled in 75 mL of N,N-dimethylformamide and a small amount of water (7.5 mL) at room temperature for 2 h. Then, it was vigorously stirred at 80 ° C under argon protection for 60 min to obtain a colorless transparent solution.

[0067] (2) 2.5 g of SPU2 obtained in Example 4 was crushed and swelled in 25 mL of N,N-dimethylformamide at room temperature for 2 h, and then vigorously stirred at 60°C under argon protection for 30 min to obtain a yellow clear solution;

[0068] (3) The colorless transparent solution of step (1) and the yellow clear solution of step (2) were mixed, stirred at 120°C under argon protection for 60 min, and most of the solvent was removed by rotary evaporation. The mixture was then placed in a 60°C oven and dried to constant weight to obtain a polymer reversible interlocking network film RILNs31.

[0069] Example 8: Method for using a polymer reversibly interlocking network film with strong adhesion, low modulus, and high damping properties

[0070] The method of use comprises the following steps:

[0071] (1) The polymer reversible interlocking network film RILNs11, RILNs21, or RILNs31 is uniformly cut into pieces and quickly hot-pressed into flat films (with a thickness of about 0.5 mm);

[0072] (2) The hot-pressed polymer reversible interlocking network film RILNs11 or RILNs21 or RILNs31 is placed between two aluminum alloy substrates, fixed with a dovetail clamp, and then hot-pressed at 100°C for 15 minutes, and then naturally cooled to room temperature. Comparative Example 1: Preparation method of a synchronous interpenetrating polymer network film IPNs1

[0073] The preparation method of the synchronous interpenetrating polymer network film IPNs1 is:

[0074] 5 g of polytetramethylene glycol (CAS No.: 25190-06-1), 3.11 g of isophorone diisocyanate (CAS No.: 4098-71-9), 2.72 g of dihydroxy-terminated borate monomer (its structure and preparation refer to "Song K, Ye W, Gao X, Fang H, Zhang Y, Zhang Q, Li X, Yang S, Wei H, Ding Y. Synergy between dynamic covalent boronic ester and boron-nitrogen coordination: strategy for self-healing polyurethane elastomers at room temperature with unprecedented mechanical properties. Materials) were prepared. Horizons, 2021, 8, 216."), 0.092g dimethylolpropionic acid (CAS No.: 4767-03-7), 0.149g triethanolamine (CAS No.: 102-71-6), 5g polylactic acid diol (CAS No.: 26780-50-7), 2.71g hexamethylene diisocyanate (CAS No.: 822-06-0), 0.76g 2-(pyridin-4-yl)-1,3-propanediol (CAS No.: 102877-55-4), 1.72g 4,4'-dithiodiphenylamine (CAS No.: 722-27-0) and 3g polyether triol (CAS No.: 9003-11-6) were added together in 50mL N,N-dimethylformamide and reacted at 60°C under nitrogen protection for 48h. After the reaction is completed, the mixture is poured into a mold and placed in an oven at 80°C to dry to constant weight, thereby obtaining a synchronous interpenetrating polymer network film IPNs1.

[0075] Comparative Example 2: Method for using synchronous interpenetrating polymer network film IPNs1

[0076] The method of use comprises the following steps:

[0077] The synchronous interpenetrating polymer network film IPNs1 prepared in Comparative Example 1 was placed between two aluminum alloy substrates, fixed with a dovetail clamp, and then hot-pressed at 100° C. for 15 minutes, and then naturally cooled to room temperature.

[0078] Comparative Example 3: A method for using commercial electronic glue

[0079] The method of use comprises the following steps:

[0080] Evenly apply commercial K704 glue on two aluminum alloy substrates to form an overlap and then leave it at room temperature for 2 days.

[0081] Comparative Example 4: A method for using commercial electronic glue

[0082] The method of use comprises the following steps:

[0083] Evenly apply commercial K705 glue on two aluminum alloy substrates to form an overlap and then leave it at room temperature for 2 days.

[0084] Comparative Example 5: A method for using commercial electronic glue

[0085] The method of use comprises the following steps:

[0086] Evenly apply commercial K5204 glue on two aluminum alloy substrates to form an overlap and then leave it at room temperature for 2 days.

[0087] Comparative Example 6: A method for using commercial electronic glue

[0088] The method of use comprises the following steps:

[0089] Evenly apply commercial K1668 glue on two aluminum alloy substrates to form an overlap and then leave it at room temperature for 2 days.

[0090] Experimental Example 1: Verification of the interlocking network structure of polymer film RILNs

[0091] The single networks BPU1 and SPU1 from Examples 1 and 3, as well as the reversibly interlocked networks RILNs11, RILNs21, and RILNs31 from Examples 5-7, were heat-pressed into uniform, bubble-free, smooth films. These films were then tested using an ORTEC 0107A positron annihilation lifetime spectrometer (PAL). The resulting positron lifetimes were used to calculate the corresponding free volume and free volume fraction.

[0092] Depend on Figure 1 It can be seen that the free volume and free volume fraction of each group of interlocked networks are significantly lower than the weighted average of the single network, indicating that they have indeed formed an interlocking structure (the judgment criteria refer to the literature "You Y, Peng WL, Xie P, et al. Topological rearrangement-derived homogeneous polymer networks capable of reversibly interlocking: From phantom to reality and beyond. Materials Today, 2019, 33, 45-55.").

[0093] Experimental Example 2: Adhesion Performance Test of Polymer Film RILNs

[0094] The polymer films prepared in Examples 5-7 were used as samples to test their bonding properties. In addition, the bonding properties of the interpenetrating network (Comparative Example 1) and various commercial electronic adhesives (Comparative Examples 3-6) were also tested for comparison.

[0095] The testing instrument is: China's WD-5A electronic universal testing machine, with a testing speed of 100mm / min.

[0096] Test method: Adhesion testing was performed using the GB / T 33334-2016 adhesive single lap tensile shear strength test method. The calculation formula is as follows:

[0097] τ=F m / (B×L);

[0098] Where: τ-tensile shear strength, unit is megapascal (MPa);

[0099] F m -The maximum force of the test, in Newtons (N);

[0100] B-bonding area width, in millimeters (mm);

[0101] L- length of the bonding area, in millimeters (mm).

[0102] As shown in Table 1, all three interlocking networks exhibited high bond strengths, reaching up to 9.7 MPa. In comparison, the bond strength of IPNs with the same formulation was only 1.1 MPa, and common commercial adhesives were generally below 2 MPa. These results demonstrate that RILNs can meet the requirements of high-strength applications.

[0103] Table 1 Bonding strength of interlocking network film and control sample

[0104] Sample name Bond strength (MPa) RILNs11 (Example 5) 7.8 RILNs21 (Example 6) 9.5 RILNs31 (Example 7) 9.7 IPNs1 (Comparative Example 1) 1.1 K704 (Comparative Example 3) 1.85 K705 (Comparative Example 4) 0.99 K5204 (Comparative Example 5) 1.52 K1668 (Comparative Example 6) 0.59

[0105] Experimental Example 3: Mechanical Properties Test of Polymer Film RILNs

[0106] Since the innovation of the present invention is to achieve both low modulus and strong adhesion, the mechanical properties of the prepared reversibly interlocking network film were first evaluated.

[0107] The RILNs 21 obtained in Example 6 was used as a representative sample and cut into 30×10 mm 2 The long strip is subjected to temperature scanning using the DMA8500 dynamic mechanical analyzer from TA of the United States to obtain the modulus of the material.

[0108] Depend on Figure 2 It can be seen that within the entire temperature range of 25-120°C, the shear modulus of RILNs21 does not exceed 1000 MPa. Since the tested temperature range has covered the normal operating temperature of the power battery, it shows that the modulus of the adhesive can meet the low modulus requirements.

[0109] In order to more comprehensively evaluate the modulus of the adhesive in various modes, in addition to the above-mentioned DMA test of the modulus of the adhesive in the shear mode, the samples were also cut into dumbbell-shaped standard samples (referring to the national standard GB / T528-1998, type 2 samples with a test length of 20.0±0.5mm). The samples were stretched using the WD-5A universal testing machine from the Guangzhou Testing Instrument Factory at a stretching rate of 100mm / min. The stress-strain curves obtained from the test are shown in the figure below. Figure 3 The linear deformation region in the stress-strain curve was selected for calculation. The results showed that the Young's modulus of the reversibly interlocking network adhesive was only 54.8 MPa, which is still relatively low. This shows that under tensile mode, the adhesive still exhibits low modulus characteristics, which meets the application requirements.

[0110] Experimental Example 4: Damping Performance Test of Polymer Film RILNs

[0111] The RILNs 21 obtained in Example 6 was used as a representative sample and the British Kinexus pro + The strain sweep test at different frequencies was carried out using a rheometer of this model to study the damping performance of the reversibly interlocking network film when facing external strain.

[0112] like Figure 4 As shown in the figure, when the reversible interlocking network film was subjected to a strain scan of 0.01-10% under multiple frequency conditions of 0.1 / 0.5 / 1.0 / 1.5 / 2.0 Hz, the results showed that within the entire test range, the loss factor of the material was significantly higher than 0.3, that is, the material exhibited high damping characteristics throughout the entire strain range, which is very beneficial for practical applications.

[0113] Experimental Example 5: Self-healing performance test of polymer film RILNs

[0114] The RILNs21 obtained in Example 6 was used as a representative sample to conduct a self-repair test: a scalpel was used to scratch the surface of the material, and then it was repaired at 60°C. After repair, the scratch morphology was observed using an Olympus 3D digital microscope from Japan.

[0115] like Figure 5As shown in the figure, the scratches on the surface of the material are gradually repaired with heating. After 12 hours of repair at 60°C, the scratches are completely closed, indicating that the adhesive can achieve self-repair under mild conditions and can be repaired by appropriate heating when facing damage during application.

[0116] Experimental Example 6: Recycling Performance Test of Polymer Film RILNs

[0117] The RILNs 21 obtained in Example 6 was used as a representative sample for a solvent recovery test: the intact sheet RILNs 21 was immersed in an anhydrous ethanol solution overnight, and the changes occurring therein with time were observed.

[0118] like Figure 6 As shown in the figure, after being soaked in ethanol for 24 h, the RILNs21 sample was completely dissolved, indicating that it can be gently and efficiently recovered as an adhesive by soaking in ethanol.

[0119] In summary, the polymer reversible interlocking network adhesive provided by the present invention can not only achieve strong adhesion to the substrate, but also maintain low modulus properties. In addition, the unique dissipation capacity of the interlocking network also gives the adhesive high damping performance. In view of the presence of a large number of dynamic bonds inside the reversible interlocking network, the interlocking network adhesive also has both self-repairing properties and recyclability. Overall, the present invention successfully solves the current contradictory problems of power battery structural adhesives by efficiently integrating low modulus single networks and strong bonding single networks in the form of reversible interlocking networks, while achieving synergistic optimization of the three key properties of strong bonding, low modulus and high damping, and the adhesive itself also has excellent self-repairing properties and recycling properties. The present invention provides an innovative solution for structural adhesives to resolve contradictions in various performance aspects and achieve synergistic optimization, which has certain theoretical and application value.

[0120] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. A polymer reversible interlocking network film with strong adhesion, low modulus and high damping, characterized in that: The polymer reversibly interlocked network film comprises, by weight percentage, 50%-91% of a strongly adhesive single network A containing dynamic covalent bonds and 9%-50% of a low modulus single network B containing dynamic covalent bonds; The strong bonding single network A comprises the following raw materials in parts by weight: 20-30 parts of diisocyanate monomer, 40-55 parts of diol monomer, 15-30 parts of dynamic covalent bond monomer, 0.5-5 parts of adhesive functional monomer, and 0.5-3 parts of crosslinking agent monomer; The low modulus single network B comprises the following raw materials in parts by weight: 30-50 parts of diisocyanate monomer, 40-60 parts of diol monomer, 10-20 parts of dynamic covalent bond monomer, 5-10 parts of damping monomer, and 10-30 parts of crosslinking agent monomer.

2. The polymer reversible interlocking network film with strong adhesion, low modulus and high damping according to claim 1, characterized in that: In the strong bonding single network A, the diisocyanate monomer is at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, o-phthalylene diisocyanate, and hexamethylene diisocyanate; the diol monomer is at least one of polyethylene glycol, polytetramethylene glycol, polypropylene glycol, polycaprolactone diol, polylactic acid diol, and polycarbonate diol; the dynamic covalent bond monomer is at least one of a dihydroxy-terminated borate monomer, a Schiff base bond-containing diol monomer, and a double-bond-terminated borate monomer; the bonding functional monomer is at least one of 3,5-dihydroxybenzonitrile, 2,3-dihydroxypropionic acid, dihydroxymaleic acid, and dimethylolpropionic acid; and the crosslinker monomer is at least one of triethanolamine, glycerol, and diethylenetriamine.

3. The polymer reversible interlocking network film with strong adhesion, low modulus and high damping according to claim 1, characterized in that: In the low modulus single network B, the diisocyanate monomer is at least one of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, o-phthalylene diisocyanate, and hexamethylene diisocyanate; the diol monomer is at least one of polyethylene glycol, polytetramethylene glycol, polypropylene glycol, polycaprolactone diol, polylactic acid diol, and polycarbonate diol; the dynamic covalent bond monomer is 4,4'-dithiodiphenylamine, 2, At least one of 2'-diaminodiphenyl disulfide, 2-hydroxyethyl disulfide, and bis(4-aminophenyl) diselenide; the damping monomer is at least one of diethyl bis(hydroxymethyl)malonate, N,N-dimethyl-N',N'-di(2-hydroxypropyl)-1,3-propylenediamine, and 2-(pyridin-4-yl)-1,3-propylene glycol; the crosslinking agent monomer is at least one of melamine-amide, polyether triol, triethanolamine, glycerol, and diethylenetriamine.

4. The polymer reversible interlocking network film with strong adhesion, low modulus and high damping according to claim 1, characterized in that: The preparation method of the strong adhesive single network A is as follows: dissolving a diol monomer and a diisocyanate monomer in an organic solvent, reacting at 50-70° C. for 10-15 hours, then adding a dynamic covalent bond monomer, an adhesive functional monomer and an organic solvent, continuing the reaction for 10-15 hours after dissolution, and finally adding a crosslinker monomer, continuing the reaction for 10-15 hours after dissolution, and drying after the reaction to obtain the product.

5. The polymer reversible interlocking network film with strong adhesion, low modulus and high damping according to claim 1, characterized in that: The preparation method of the low modulus single network B is as follows: dissolving a diol monomer and a diisocyanate monomer in an organic solvent, reacting at 50-70° C. for 10-15 hours, then adding a damping monomer, a dynamic covalent bond monomer and an organic solvent, continuing the reaction for 10-15 hours, and finally adding a crosslinker monomer, continuing the reaction for 10-15 hours, and drying after the reaction.

6. The method for preparing the polymer reversibly interlocked network film with strong adhesion, low modulus and high damping according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. crushing a strong adhesive single network A containing dynamic covalent bonds and a low modulus single network B containing dynamic covalent bonds, respectively, and swelling them in an organic solvent, and mixing them to obtain solutions A and B; S2. Mix solution A and solution B at 80° C.-130° C. in an inert gas atmosphere, remove most of the solvent, and then dry to obtain the product.

7. The method for preparing a polymer reversibly interlocked network film with strong adhesion, low modulus, and high damping according to claim 6, characterized in that: The organic solvent includes at least one of N,N-dimethylformamide, tetrahydrofuran, and dichloromethane.

8. The method for preparing a polymer reversibly interlocked network film with strong adhesion, low modulus, and high damping according to claim 6, characterized in that: The swelling is carried out at room temperature for 1-3 hours.

9. The method for preparing a polymer reversibly interlocked network film with strong adhesion, low modulus, and high damping according to claim 6, characterized in that: The drying temperature is 60-100° C., and the drying is performed to a constant weight.

10. Use of the polymer reversible interlocking network adhesive film with strong adhesion, low modulus and high damping according to any one of claims 1 to 5 in power battery structural adhesive.

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