DA bond polymer film with antibacterial and self-repairing functions as well as preparation method and use method of DA bond polymer film

Abstract

The invention discloses a DA bond polymer with antibacterial and self-repairing functions for a wood surface as well as a preparation method and a use method of the DA bond polymer. Chitosan serves as a wall material, cinnamon essential oil serves as a core material, the cinnamon essential oil and chitosan antibacterial microcapsules are prepared through emulsification, crosslinking and spray drying, and essential oil controlled release is achieved. Then bisphenol A diglycidyl ether DGEBA and furfuryl alcohol FA are used as raw materials, furyl functional epoxy resin FER is prepared under the catalysis of triethylamine TEA, bismaleimide BMI is added, and a DA bond self-repairing polymer is prepared through a DA reaction; and adding 4, 4-diaminodiphenylmethane DDM into the system, reacting with redundant DGEBA to generate a cross-linked polymer network, and adding the microcapsules into a DA bond semi-interpenetrating self-repairing network solution to obtain the DA bond polymer. A thin film formed by brushing and curing wood has antibacterial and self-repairing functions, scratches and microcracks on the surface of the wood can be repaired, and microbial erosion is inhibited.

Description

Technical Field

[0001] This invention relates to the field of wood protective materials, specifically a DA bond polymer that combines cinnamon essential oil antibacterial microcapsules with a Diels-Alder (DA) bond self-healing system to achieve dual "physical-biological" protection for wood, and its preparation method. It is suitable for surface protection of high-end furniture, wood flooring, and ancient building wood, and can extend the service life of wood products and reduce maintenance costs. Background Technology

[0002] Wood, as a renewable and biodegradable green material, is increasingly widely used in the home furnishing and construction industries due to its advantages such as ease of processing, lightweight yet high strength, and beautiful color. However, the inherent porous structure and biological characteristics of wood present it with two core problems: physical damage, namely, scratches and microcracks that easily occur during daily use, and biological erosion, namely, the porous structure that easily breeds microorganisms such as mold and decay fungi. Microbial metabolism can damage the cell wall structure of wood, leading to decay and discoloration, and severely reducing the performance and usability of the wood.

[0003] Currently, research on wood protection mainly focuses on single-function materials. Intrinsic self-healing materials based on the DA reaction, using furan derivatives as dienes and maleimide derivatives as dienophiles, possess mild repair conditions, high repair efficiency, and multiple repair capabilities, which can solve physical damage problems. However, they lack antibacterial functions and cannot cope with microbial erosion. Most current DA bond self-healing materials are single linear networks, which have the defects of poor mechanical properties and inability to be used for a long time. If a semi-interpenetrating network is prepared by a "two-step method" (first prepare DA resin, then mix epoxy resin), network separation is likely to occur, resulting in a decrease in self-healing rate.

[0004] Among antibacterial materials, plant-derived cinnamon essential oil has become a research hotspot due to its strong antibacterial activity, green safety, and low cost. Its main active ingredient, cinnamaldehyde, can achieve multi-target antibacterial effects by disrupting microbial cell membranes, inhibiting enzyme activity, and interfering with quorum sensing. However, the essential oil is volatile and has poor chemical stability, resulting in a short duration of antibacterial effect when applied directly. Although microencapsulation technology can encapsulate cinnamon essential oil to control release and improve stability, existing antibacterial microcapsules are mostly used in single-function coatings and are not combined with self-healing systems, failing to simultaneously address the dual problems of physical damage and biological erosion in wood. Therefore, developing a wood surface protection material with both "damage self-healing" and "active antibacterial" functions is key to overcoming current technological bottlenecks and meeting the demand for efficient wood protection, and is of great significance for promoting the development of green wood protection technology. Summary of the Invention

[0005] To address the shortcomings of existing wood protective materials, such as their limited functionality, inability to simultaneously solve the problems of physical damage self-repair and microbial antibacterial properties, the volatility of cinnamon essential oil, and the lack of antibacterial properties in the DA bond self-repair system, this invention provides a lignin-based DA bond polymer with both antibacterial and self-repair functions, as well as its preparation method. When coated on wood, it forms a self-repairing film, achieving synergistic "physical-biological" protection of wood, extending the service life of wood products, and meeting the requirements of green, low-carbon, and sustainable development.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0007] A DA-bonded polymer for use on wood surfaces, possessing both antibacterial and self-healing properties, comprises the following raw materials in parts by weight:

[0008] 5-12 parts by weight of cinnamon essential oil, 3-8 parts by weight of chitosan, 0.3-0.55 parts by weight of acetic acid, 20-45 parts by weight of deionized water, 1-3 parts by weight of Tween 80, 1-3 parts by weight of sodium tripolyphosphate (STPP), 15-22 parts by weight of bisphenol A diglycidyl ether (DGEBA), 3.8-5.7 parts by weight of furfuryl alcohol (FA), 0.3-0.5 parts by weight of triethylamine (TEA), 17-24 parts by weight of bismaleimide (BMI), 2.5-4.5 parts by weight of 4,4-diaminodiphenylmethane (DDM), and 140-160 parts by weight of tetrahydrofuran (THF).

[0009] As a preferred embodiment of a further improvement of the present invention, the DA bond polymer comprises the following raw materials in parts by weight:

[0010] 6-10 parts by weight of cinnamon essential oil, 4-6 parts by weight of chitosan, 0.35-0.5 parts by weight of acetic acid, 30-40 parts by weight of deionized water, 1.5-2.5 parts by weight of Tween 80, 1.5-2.5 parts by weight of sodium tripolyphosphate (STPP), 17-20 parts by weight of bisphenol A diglycidyl ether (DGEBA), 4-5.5 parts by weight of furfuryl alcohol (FA), 0.4-0.45 parts by weight of triethylamine (TEA), 18-23 parts by weight of bismaleimide (BMI), 3-4 parts by weight of 4,4-diaminodiphenylmethane (DDM), and 145-155 parts by weight of tetrahydrofuran (THF).

[0011] The above-mentioned method for preparing DA-bonded polymers with both antibacterial and self-healing functions for wood surfaces includes the following steps:

[0012] (1) Dissolve an appropriate amount of acetic acid in deionized water, then weigh an appropriate amount of chitosan and add it to the acetic acid solution. Mix the mixture using a magnetic stirrer and react for a period of time to obtain a wall material chitosan solution.

[0013] (2) Add emulsifier Tween80 to deionized water and mix evenly. Add cinnamon essential oil dropwise and emulsify using a magnetic stirring device. After emulsifying for a period of time, sonicate and emulsify for another period of time to obtain a uniformly dispersed core material emulsion.

[0014] (3) Place the core material emulsion in a magnetic stirring device, and then slowly add the wall material chitosan solution, controlling the dropping speed to ensure full contact with the core material emulsion. Maintain the pH of the system by adding acetic acid, and microencapsulate for a period of time to obtain cinnamon oil@chitosan solution; weigh STPP into deionized water, add it dropwise to the cinnamon oil@chitosan solution, and cross-link for a period of time.

[0015] (4) After the cross-linking reaction, the cinnamon essential oil@chitosan solution was left to stand for a long time and then spray-dried using a spray dryer; the powder in the spray dryer was collected to obtain cinnamon essential oil@chitosan microcapsules;

[0016] (5) Add DGEBA and FA to a beaker, add THF and TEA, mix with a magnetic stirrer, stir for a period of time to obtain furanyl functionalized epoxy resin FFER; then add BMI, add an appropriate amount of THF as a solvent, heat and stir for a period of time to obtain DA bond self-healing polymer solution; then add DDM, continue stirring for a period of time, and use the excess DGEBA to react with DDM to form DA bond semi-interpenetrating self-healing network solution;

[0017] (6) Add an appropriate amount of microcapsules to the DA bond semi-interpenetrating self-healing network solution according to the proportion, mix and stir to obtain a DA bond polymer with both antibacterial and self-healing functions for use on wood surfaces.

[0018] In the above-mentioned method for preparing DA bond polymer, in step (1), acetic acid and deionized water are mixed to prepare an acidic solution. The temperature of the magnetic stirring device is set to 45°C and the rotation speed is 600 rpm. The reaction time is 1 h to ensure that chitosan is completely dissolved and a uniform and transparent chitosan solution for wall material is formed.

[0019] In the above-mentioned method for preparing DA bond polymer, in step (2), emulsification is carried out in a water bath. The water bath temperature is set to 45℃ and the rotation speed is 1200 rpm. Emulsification is carried out for 1 hour, followed by ultrasonication for 10 minutes and then emulsification for 30 minutes. The ultrasonic power is 300-500 W to ensure that the cinnamon essential oil is fully emulsified to form a core material emulsion with uniform particle size distribution.

[0020] In the above-mentioned method for preparing DA bond polymers, in step (3), the dropping rate of the chitosan solution for the wall material is controlled at 1-2 drops / second, the pH of the system is maintained between 3.8 and 4.0, and the microencapsulation time is 1 h; sodium tripolyphosphate (STPP) is dissolved in deionized water at a mass ratio of 1:3-1:9, the crosslinking reaction temperature is room temperature (25±2℃), and the reaction time is 3 h, to ensure the formation of a structurally stable cinnamon oil@chitosan microcapsule precursor.

[0021] In the above-mentioned method for preparing DA bond polymers, in step (4), the inlet air temperature of the spray dryer is set to 110℃, the feed rate is 200 mL / h, the particle size of the collected microcapsule powder is controlled to be 3-10 μm, and the microcapsule encapsulation rate is ≥80%.

[0022] In the above-mentioned method for preparing DA-bonded polymers, in step (5), the mass ratio of DGEBA to FA is 3.5:1-5.5:1, and the initial addition of THF is 50 g. When preparing furanyl functionalized epoxy resin FFER, the temperature of the magnetic stirrer is 65℃ and the stirring time is 5 h until the solution becomes viscous and clear. After adding BMI, THF is added until the total solvent volume of the system is 150 g (including the initial 50 g), the heating temperature is 65℃ and the stirring time is 40 min to ensure that the DA reaction proceeds fully. After adding DDM, the temperature is raised to 60℃ and the stirring time is 1.5 h to allow the excess DGEBA to react completely with DDM, ultimately forming a DA-bonded semi-interpenetrating self-healing network solution with a "DA-bonded linear network - epoxy resin crosslinking network" semi-interpenetrating structure.

[0023] In the above-mentioned method for preparing DA bond polymers, in step (6), the mass ratio of microcapsules to DA bond semi-interpenetrating self-healing network solution is 1:13, and the microcapsules are uniformly dispersed during stirring.

[0024] The method of using DA bond polymer is to apply the DA bond polymer to the wood surface by brushing, and form a coating after drying and curing; the coating amount is controlled at 400 g / m², the drying and curing temperature is 60℃, and the curing time is 6 h.

[0025] Core Principles

[0026] The core functionality of this invention relies on the synergistic effect of the "DA bond self-repair mechanism" and the "cinnamon essential oil antibacterial mechanism," the specific principles of which are as follows:

[0027] (1) DA bond self-repair principle

[0028] DA crosslinking reaction to construct a network: Furan-based grafted intermediates and furan-functionalized epoxy resin (FFER) furan groups (dienes) and maleimide groups (dienesophiles) in bismaleimide (BMI) undergo a [4+2] cycloaddition DA reaction at 50°C to form a reversible six-membered ring chemical structure, thereby constructing a semi-interpenetrating network (semi-IPN). In this network, the linear FFER polymer and the crosslinked furan-based intermediate-BMI polymer interpenetrate each other, ensuring both structural stability and reversible bonding.

[0029] Damage repair process: When the film is subjected to physical damage such as scratches and microcracks, the DA bonds at the damaged site break due to external force, and the network structure is locally destroyed. Under the conditions of room temperature or slight heating (40~60℃), the free furan groups generated by the breakage can undergo a DA cycloaddition reaction with the maleimide groups, realizing the reconstruction of chemical bonds and the repair of network structure, so that the damaged site heals. The repair efficiency can reach more than 80% according to the test.

[0030] (2) Antibacterial principle of cinnamon essential oil

[0031] Microcapsule controlled-release mechanism: Chitosan wall material has excellent sealing properties and pH responsiveness, which can encapsulate cinnamon essential oil inside, effectively inhibiting its volatilization and oxidation. When mold, decay fungi, or other microorganisms appear on the wood surface or in the surrounding environment, the microbial metabolism produces acidic substances (such as organic acids). These acidic substances can slowly degrade the microcapsule wall material, creating micropores. As the wall material degrades, the encapsulated cinnamon essential oil is slowly released through these pores, achieving "on-demand release" and prolonging the antibacterial effect, as shown in the attached figure. Figure 2 As shown;

[0032] Multi-target antibacterial mechanism: The main active ingredient in the released cinnamon essential oil, cinnamaldehyde, can achieve antibacterial effects through three pathways: ① As a surfactant, it embeds itself in the phospholipid bilayer of the microbial cell membrane, disrupting the membrane's integrity and permeability, leading to leakage of cell contents (such as proteins and nucleic acids), ultimately causing cell death; ② It binds to the active sites of enzymes (such as dehydrogenases and oxidases) within the microbial cell, inactivating the enzymes and interfering with cellular energy metabolism and substance synthesis; ③ It interferes with the bacterial quorum sensing system, preventing signal transmission between bacteria, inhibiting biofilm formation, and preventing microbial aggregation and reproduction, thereby achieving highly efficient inhibition of wood-decaying fungi and molds, with an inhibition rate of over 90%.

[0033] (3) Reinforcement principle of semi-interpenetrating network structure

[0034] The semi-interpenetrating network structure consists of two parts: one is the linear polymer chain formed by the reaction of FFER and BMI, as shown in the attached figure. Figure 3As shown in the figure; secondly, the excess DGEBA in the system is used to continue reacting with DDM to generate a cross-linked polymer network, as shown in the attached figure. Figure 4 As shown, this structure exhibits high strength and stability, enhancing the film's ductility and impact resistance, preventing cracking due to excessive brittleness, providing structural support, and ensuring the density and reversibility of the DA bonds to guarantee self-healing efficiency. The two elements interpenetrate and synergistically enhance the film's high self-healing performance while maintaining excellent mechanical strength and operational stability. This network structure not only provides a stable dispersion environment for the microcapsules, but its interfacial interaction with the microcapsule wall material has also been shown to improve the self-healing kinetics of the entire composite material. Furthermore, the antibacterial microcapsules can be uniformly dispersed within the pores of the semi-interpenetrating network, preventing microcapsule aggregation and ensuring the uniformity of antibacterial properties across different regions of the film.

[0035] Innovation

[0036] This invention pioneers a "one-step" method for constructing semi-interpenetrating self-healing networks: It eliminates the need for separate preparation of type A / type B resins. By pre-adding an excess of DGEBA to the DA reaction system, followed by the direct addition of DDM, both networks can be formed simultaneously, simplifying the process and reducing industrial production costs. This invention overcomes the shortcomings of the "two-step" method by simultaneously constructing dual networks in a "one-step" manner, filling the gap in integrated technology that combines "highly efficient self-healing, excellent mechanical properties, and simplified processes."

[0037] For the first time, cinnamon essential oil antibacterial microcapsules are introduced as a functional unit into the DA bond self-healing system, breaking through the limitation of the traditional wood protection materials' "single function" and achieving the dual functions of "physical damage self-repair" and "microbial antibacterial". This solves two major pain points in the use of wood and fills the technological gap in multifunctional integrated wood protection materials.

[0038] The study systematically investigates the interfacial bonding between the smart film and wood, its antibacterial properties, and its self-healing efficiency, providing complete data support and theoretical basis for subsequent development.

[0039] The beneficial effects of this invention are as follows:

[0040] Synergistic Dual Functions: Through specific formulation and structural design, this invention achieves, for the first time, a synergistic effect between cinnamon essential oil antibacterial microcapsules and a DA bond self-repair system. Experiments show that this system not only possesses dual functions but also unexpectedly achieves a significant improvement in self-repair efficiency and a qualitative leap in antibacterial longevity.

[0041] Green and environmentally friendly: The raw materials are mainly natural and renewable resources (chitosan, cinnamon essential oil), with no formaldehyde or volatile organic compound residues;

[0042] Long-lasting and stable: Cinnamon essential oil is encapsulated in pH-responsive chitosan microcapsules, enabling "on-demand release" and extending the antibacterial effect to more than 6 months; the DA bond self-repair system can repair multiple times, improving the coating's lifespan;

[0043] The process is feasible: the preparation process does not require complex equipment, and processes such as spray drying and brushing are easy to mass-produce industrially. It is also compatible with existing wood finishing processes and has low application costs. Attached Figure Description

[0044] Figure 1 This is a process flow diagram of the present invention.

[0045] Figure 2 Schematic diagram of the antibacterial principle of cinnamon essential oil@chitosan microcapsules.

[0046] Figure 3 This is a flowchart of the synthesis process of DA bond self-healing polymer solutions.

[0047] Figure 4 This is a flowchart of the synthesis process of cross-linked polymer networks. Detailed Implementation

[0048] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0049] Example 1:

[0050] like Figure 1 As shown, this embodiment provides a DA-bonded polymer with both antibacterial and self-healing functions, and its preparation method, including the following steps:

[0051] (1) Dissolve 0.4 g of acetic acid in 20 g of deionized water to prepare an acidic solution. Then weigh 4 g of chitosan and add it to the acetic acid solution. Mix the mixture using a magnetic stirrer. Set the temperature of the magnetic stirrer to 45°C and the rotation speed to 600 rpm. React for 1 h to obtain a chitosan solution for the wall material.

[0052] (2) Add 1.5g of emulsifier Tween80 to 10g of deionized water and mix evenly. Add 6g of cinnamon essential oil. Set the water bath temperature to 45°C and the rotation speed to 1200 rpm. After emulsifying for 1 h, sonicate for 10 min and then emulsify for 30 min to obtain a uniformly dispersed core material emulsion.

[0053] (3) The core material emulsion was placed in a magnetic stirrer and the speed was set to 600 rpm. Then, the wall material chitosan solution was slowly added dropwise, and the dropping rate was controlled to ensure that it was in full contact with the core material emulsion. The pH of the system was maintained at 4.0 by adding acetic acid. Microencapsulation was carried out for 1 h to obtain cinnamon oil@chitosan solution. 1.5 g of STPP was weighed into 10 g of deionized water and added dropwise to the cinnamon oil@chitosan solution. The cross-linking reaction was carried out for 3 h.

[0054] (4) The cinnamon oil@chitosan solution after the cross-linking reaction was allowed to stand for 12 h and then spray-dried. The temperature of the spray dryer was set to 110°C and the feed rate was 200 mL / h. The powder in the spray dryer was collected to obtain cinnamon oil@chitosan microcapsules.

[0055] (5) Add 19g DGEBA and 4g FA to a beaker, then add 50g THF and 0.3g TEA. Set the magnetic stirrer to 65°C and stir for 5 h to obtain furanyl functionalized epoxy resin (FFER); then add 20g BMI and 100g THF as solvent, and stir at 65°C for 40 min to obtain a DA bond self-healing polymer solution. Subsequently, add 3.3g DDM, heat to 60°C and stir for 1.5 h to form a DA bond semi-interpenetrating self-healing network solution.

[0056] (6) Add 1g of microcapsules to 13g of DA-bonded semi-interpenetrating self-healing network solution, mix and stir to obtain DA-bonded polymer. Brush the DA-bonded polymer onto pine wood (coating amount 400 g / m²), cure at 60℃ for 6 h, and form a DA-bonded polymer film with both antibacterial and self-healing functions on the surface of the pine wood.

[0057] Example 2:

[0058] (1) Dissolve 0.4g of acetic acid in 20g of deionized water to prepare an acidic solution. Then weigh 4g of chitosan and add it to the acetic acid solution. Mix the mixture using a magnetic stirrer. Set the temperature of the magnetic stirrer to 45°C and the rotation speed to 600 rpm. React for 1 h to obtain a chitosan solution for the wall material.

[0059] (2) Add 2g of emulsifier Tween80 to 10g of deionized water and mix evenly. Add 8g of cinnamon essential oil. Set the water bath temperature to 45°C and the rotation speed to 1200 rpm. After emulsifying for 1 h, sonicate for 10 min and then emulsify for 30 min to obtain a uniformly dispersed core material emulsion.

[0060] (3) The core material emulsion was placed in a magnetic stirrer and the speed was set to 600 rpm. Then, the wall material chitosan solution was slowly added dropwise, and the dropping rate was controlled to ensure full contact with the core material emulsion. The pH of the system was maintained at 3.8 by adding acetic acid. Microencapsulation was carried out for 1 h to obtain cinnamon oil@chitosan solution. 1.5 g of STPP was weighed into 10 g of deionized water and added dropwise to the cinnamon oil@chitosan solution. The cross-linking reaction was carried out for 3 h.

[0061] (4) The cinnamon oil@chitosan solution after the cross-linking reaction was allowed to stand for 12 h and then spray-dried. The temperature of the spray dryer was set to 110°C and the feed rate was 200 mL / h. The powder in the spray dryer was collected to obtain cinnamon oil@chitosan microcapsules.

[0062] (5) Add 20g DGEBA and 4.2g FA to a beaker, then add 50g THF and 0.4g TEA. Set the temperature of the magnetic stirrer to 65°C and stir for 5 h to obtain furanyl functionalized epoxy resin (FFER); then add 17g BMI and an appropriate amount of 100g THF as a solvent, and stir at 65°C for 40 min to obtain a DA bond self-healing polymer solution. Subsequently, add 2.5g DDM, raise the temperature to 60°C, and stir for 1.5 h to form a DA bond semi-interpenetrating self-healing network solution.

[0063] (6) Add 1g of microcapsules to 13g of DA-bonded semi-interpenetrating self-healing network solution, mix and stir to obtain DA-bonded polymer. Brush the DA-bonded polymer onto pine wood (coating amount 400 g / m²), cure at 60℃ for 6 h, and form a DA-bonded polymer film with both antibacterial and self-healing functions on the surface of the pine wood.

[0064] Example 3:

[0065] (1) Dissolve 0.3g of acetic acid in 15g of deionized water to prepare an acidic solution. Then weigh 5g of chitosan and add it to the acetic acid solution. Mix the mixture using a magnetic stirrer. Set the temperature of the magnetic stirrer to 45°C and the rotation speed to 600 rpm. React for 1 h to obtain a chitosan solution for the wall material.

[0066] (2) Add 2g of emulsifier Tween80 to 10g of deionized water and mix well. Add 10g of cinnamon essential oil. Set the water bath temperature to 45°C and the rotation speed to 1200 rpm. After emulsifying for 1 h, sonicate for 10 min and then emulsify for 30 min to obtain a uniformly dispersed core material emulsion.

[0067] (3) The core material emulsion was placed in a magnetic stirrer and the speed was set to 600 rpm. Then, the wall material chitosan solution was slowly added dropwise, and the dropping rate was controlled to ensure that it was in full contact with the core material emulsion. The pH of the system was maintained at 3.8 by adding acetic acid. Microencapsulation was carried out for 1 h to obtain cinnamon oil@chitosan solution. 1.5 g of STPP was weighed into 5 g of deionized water and added dropwise to the cinnamon oil@chitosan solution. The cross-linking reaction was carried out for 3 h.

[0068] (4) The cinnamon oil@chitosan solution after the cross-linking reaction was allowed to stand for 12 h and then spray-dried. The temperature of the spray dryer was set to 110°C and the feed rate was 200 mL / h. The powder in the spray dryer was collected to obtain cinnamon oil@chitosan microcapsules.

[0069] (5) Add 20g DGEBA and 5.5g FA to a beaker, then add 50g THF and 0.4g TEA. Set the magnetic stirrer to 65°C and stir for 5 h to obtain furanyl functionalized epoxy resin (FFER); then add 21g BMI and an appropriate amount of 100g THF as a solvent, and stir at 65°C for 40 min to obtain a DA bond self-healing polymer solution. Subsequently, add 4.3g DDM, heat to 60°C and stir for 1.5 h to form a DA bond semi-interpenetrating self-healing network solution.

[0070] (6) Add 1g of microcapsules to 13g of DA-bonded semi-interpenetrating self-healing network solution, mix and stir to obtain DA-bonded polymer. Brush the DA-bonded polymer onto pine wood (coating amount 400 g / m²), cure at 60℃ for 6 h, and form a DA-bonded polymer film with both antibacterial and self-healing functions on the surface of the pine wood.

[0071] Example 4:

[0072] (1) Dissolve 0.35g of acetic acid in 17.5g of deionized water to prepare an acidic solution. Then weigh 4g of chitosan and add it to the acetic acid solution. Mix the mixture using a magnetic stirrer. Set the temperature of the magnetic stirrer to 45°C and the rotation speed to 600 rpm. React for 1 h to obtain a chitosan solution for the wall material.

[0073] (2) Add 2.5g of emulsifier Tween80 to 10.5g of deionized water and mix well. Add 10g of cinnamon essential oil. Set the water bath temperature to 45°C and the rotation speed to 1200 rpm. After emulsifying for 1 h, sonicate for 10 min and then emulsify for 30 min to obtain a uniformly dispersed core material emulsion.

[0074] (3) The core material emulsion was placed in a magnetic stirrer and the speed was set to 600 rpm. Then, the wall material chitosan solution was slowly added dropwise, and the dropping rate was controlled to ensure that it was in full contact with the core material emulsion. The pH of the system was maintained at 4 by adding acetic acid. Microencapsulation was carried out for 1 h to obtain cinnamon oil@chitosan solution. 2 g of STPP was weighed into 7 g of deionized water and added dropwise to the cinnamon oil@chitosan solution. The cross-linking reaction was carried out for 3 h.

[0075] (4) The cinnamon oil@chitosan solution after the cross-linking reaction was allowed to stand for 12 h and then spray-dried. The temperature of the spray dryer was set to 110°C and the feed rate was 200 mL / h. The powder in the spray dryer was collected to obtain cinnamon oil@chitosan microcapsules.

[0076] (5) Add 21g DGEBA and 4g FA to a beaker, then add 50g THF and 0.35g TEA. Set the temperature of the magnetic stirrer to 65°C and stir for 5 h to obtain furanyl functionalized epoxy resin (FFER); then add 18g BMI and an appropriate amount of 100g THF as a solvent, and stir at 65°C for 40 min to obtain a DA bond self-healing polymer solution. Then add 2.8g DDM, heat to 60°C and stir for 1.5 h to form a DA bond semi-interpenetrating self-healing network solution;

[0077] (6) Add 1g of microcapsules to 13g of DA-bonded semi-interpenetrating self-healing network solution, mix and stir to obtain DA-bonded polymer. Brush the DA-bonded polymer onto pine wood (coating amount 400 g / m²), cure at 60℃ for 6 h, and form a DA-bonded polymer film with both antibacterial and self-healing functions on the surface of the pine wood.

[0078] Performance testing:

[0079] According to GB / T 4893.6-2013, the gloss of the DA-bonded polymer films with antibacterial and self-healing functions formed on the pine wood surface in Examples 1-4 was tested using a gloss meter; according to GB / T 4893.8-2013, the abrasion resistance of the films was tested using the abrasion resistance tester; according to GB / T 4893.9-2013, the impact resistance of the films was tested using a coating impact resistance tester; the antibacterial effect against Escherichia coli and Staphylococcus aureus was tested using the "inhibition zone diameter method" (GB / T 21510-2008); the antibacterial rate at 24h, 72h, and 168h (7 days) was tested using the "colony counting method" to evaluate the long-term effectiveness; the self-healing rate of the films was tested using a scratch test and compared with a pure epoxy resin paint surface. The test results are shown in Table 1 below.

[0080] This invention enables the coating to possess gloss, abrasion resistance, impact resistance, antibacterial properties, and self-healing ability. The polymer of this invention was coated on the surface of pine wood (100 mm × 100 mm × 12 mm). According to national standard GB / T 4893.6-2013, the coating gloss was high-gloss; according to national standard GB / T 4893.8-2013, the abrasion resistance was grade 1 (5000 revolutions); and according to national standard GB / T 4893.9-2013, the impact resistance was grade 2. A self-healing rate test was conducted on the coating film. Using an 8×19 mm single-edged blade, scratches were made on the surface of the experimental sample. The scratch width was immediately observed under a microscope and recorded as H0. Five days later, the scratch width was observed again under a microscope and recorded as H1. The self-healing rate was calculated using the following formula:

[0081] H = (H0 - H1) / H0 · 100%.

[0082] Table 1 shows the test results:

[0083] Coating type Gloss Coating film abrasion resistance (abrasion rotation number 5000 rotations) Paint film impact resistance (impact height 100㎜) Self-repair rate (%) Example 1 High gloss 2nd grade 2nd grade 85 Example 2 High gloss 2nd grade 2nd grade 85 Example 3 High gloss 2nd grade 2nd grade 80 Example 4 High gloss 2nd grade 2nd grade 90 Comparative example (epoxy resin coating) High gloss 4th grade 4th grade 0

[0084] Example Comparison

[0085] Comparative Example 1: Simple Chitosan-Encapsulated Cinnamon Oil Film

[0086] 1. Formulation and Preparation Process

[0087] The preparation process of Comparative Example 1 is basically the same as that of Example 1, except that the components related to the self-healing system are removed. The remaining raw material amounts and process parameters are the same as those in Example 1.

[0088] (1) Follow the steps (1)-(4) of Example 1, specifically as follows: Dissolve 0.4g of acetic acid in 20g of deionized water, add 4g of chitosan, and mix using a magnetic stirrer. Set the temperature of the magnetic stirrer to 45°C and the rotation speed to 600rpm, react for 1h, and obtain a wall material chitosan solution; Dissolve 1.5g of Tween80 in 10g of deionized water, add 6g of cinnamon oil, set the temperature of the water bath to 45°C and the rotation speed to 1200rpm, emulsify for 1h, sonicate for 10min, and then emulsify for 30min to obtain a uniformly dispersed core material emulsion; Mix the core material emulsion with the chitosan solution, maintain the pH of the system at 4.0 by adding acetic acid, microencapsulate for 1h, and obtain a cinnamon oil@chitosan solution. Weigh 1.5g of STPP into 10g of deionized water, add it dropwise to the cinnamon oil@chitosan solution, and crosslink for 3h. After standing for 12 hours, the mixture was spray-dried. The spray dryer temperature was set to 110℃ and the feed rate was set to 200mL / h. The cinnamon essential oil@chitosan microcapsules in the spray dryer were collected.

[0089] (2) No Example 1, step (5) (no addition of self-healing components such as DGEBA, FA, TEA, BMI, DDM, THF).

[0090] (3) Preparation of a separate film for testing: Take 1g of collected microcapsules, add a small amount of ethanol (the amount is the same as the volume of the DA bond semi-interpenetrating self-healing network solution in step (6) of Example 1), stir at 300 rpm for 30 min to form a uniform polymer; coat the above polymer uniformly on a horizontally placed polytetrafluoroethylene template (size 100mm×150mm), control the coating amount to be 400 g / m², and cure at 60℃ for 6 h; after curing, peel off the template to obtain an independent chitosan-embedded cinnamon essential oil film with a thickness of about 0.1mm, which will be used for subsequent performance testing.

[0091] (4) Verification of wood surface coating: Take another polymer and apply it to pine wood using the coating process in Example 1 (coating amount 400g / m²). 2 (Cure at 60℃ for 6 hours) for functional effect verification.

[0092] 2. Performance Testing

[0093] Tensile strength recovery rate test: Referring to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", standard specimens (dumbbell-shaped Type 5, total length 130 mm) were prepared from the above-mentioned independent films; only the original tensile strength was tested (without repair process). The results showed that there was no sign of self-healing after fracture, so the tensile strength recovery rate was 0%.

[0094] 7-day essential oil retention rate test: The solvent extraction method in GB / T 21866-2008 "Determination of antibacterial properties of coatings and varnishes (films)" was used. 0.5g of film sample was accurately weighed and ultrasonically extracted with anhydrous ethanol for 30min (300W power). The concentration of cinnamon essential oil in the extract was determined by gas chromatography (GC-2014, Shimadzu Corporation, Kyoto, Japan). The proportion of essential oil residue after 7 days to the initial content was calculated, and the 7-day essential oil retention rate was 38.5%.

[0095] 3. Performance data of Comparative Example 1

[0096] Test item E. coli S. aureus Tensile strength recovery rate 7-day essential oil retention rate Inhibition zone diameter (mm) 12.3±0.2 13.1±0.3 0% (no repairability) 38.5% 7-day antibacterial rate (%) 52.1±1.8 58.3±2.1 - -

[0097] 4. Conclusion

[0098] It can only achieve short-term antibacterial effects, has no self-repair function, and the essential oil evaporates quickly, resulting in poor long-term effectiveness.

[0099] Comparative Example 2: Simple DA-bond semi-interpenetrating network polymer film

[0100] 1. Formulation and Preparation Process

[0101] The preparation process of Comparative Example 2 is basically the same as that of Example 1, except that the antibacterial microcapsule-related components are omitted. The remaining raw material amounts and process parameters are the same as those in Example 1.

[0102] (1) No Example 1 steps (1)-(4) (no addition of antibacterial components such as cinnamon oil, chitosan, Tween80, STPP, etc.).

[0103] (2) Follow the steps (5) of Example 1, specifically as follows: Add 19g DGEBA and 4g FA to a beaker, add 50g THF and 0.3g TEA, set the temperature of the magnetic stirrer to 65°C, and stir for 5 h to obtain furanyl functionalized epoxy resin (FFER); then add 20g BMI and 100g THF as solvent, set the temperature of the magnetic stirrer to 65°C, and stir for 40 min to obtain a DA bond self-healing polymer solution. Add 3.3g DDM, heat to 60°C and stir for 1.5 h to form a DA bond semi-interpenetrating self-healing network solution.

[0104] (3) Preparation of individual films for testing: Take the above-mentioned DA bond semi-interpenetrating self-healing network solution and coat it evenly on a horizontally placed polytetrafluoroethylene template (size 100mm×150mm). Control the coating amount to 400g / m² and cure at 60℃ for 6h. After curing, peel off the template to obtain an independent pure DA bond semi-interpenetrating network polymer film (thickness about 0.1mm) for subsequent performance testing.

[0105] (4) Wood surface coating verification: Take another DA bond semi-interpenetrating self-healing network solution and apply it to pine wood according to the coating process in Example 1 (coating amount 400g / m²), cure at 60℃ for 6h, and use it to verify the functional effect.

[0106] 2. Performance Testing

[0107] Tensile strength recovery rate test: Referring to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", a standard specimen, Type 5, with a total length of 130 mm and a film thickness equal to the actual thickness after curing, was prepared first. The original tensile strength was tested (28.6 ± 1.2 MPa). A notch was made in the center of the specimen's length direction using a single-edged blade, with a notch width of 0.2 mm, a depth of 1 / 2 the film thickness (approximately 0.05 mm), and a length of 5 mm (parallel to the specimen's width direction). The notched specimen was placed in an 80℃ constant temperature oven for 2 hours for repair. After cooling to room temperature, the tensile strength was tested again using a universal testing machine (22.4 ± 1.0 MPa). The tensile strength recovery rate was calculated using the formula "Recovery rate = (Repaired strength / Original strength) × 100%", yielding 78.2 ± 2.3%.

[0108] Mechanical strength test: Same as GB / T 1040.3-2006, using dumbbell-shaped standard specimens (Type 5, conforming to the national standard for thin film / sheet specimens), with specimen dimensions consistent with the tensile strength recovery rate test; tested on a universal testing machine at a speed of 5 mm / min, tensile strength 28.6±1.2 MPa, elongation at break 15.3±1.1%;

[0109] 3. Performance data of Comparative Example 2

[0110] Test item E. coli S. aureus Tensile strength recovery rate Mechanical strength (MPa) Inhibition zone diameter (mm) 0 (no antibacterial property) 0 (no antibacterial property) 78.2±2.3% 28.6±1.2 7-day antibacterial rate (%) 0% 0% - -

[0111] 4. Conclusion

[0112] It has self-healing capabilities, but lacks antibacterial activity, thus failing to meet the synergistic requirement of "antibacterial-self-healing".

[0113] Comparative Example 3: Non-specific ratio mixture (microcapsules in excess, content 15%)

[0114] 1. Formulation and Preparation Process

[0115] The preparation process of Comparative Example 3 is basically the same as that of Example 1, except that the amount of microcapsules added is adjusted to 15% (1g:14g≈7% in Example 1). The amounts of other raw materials and process parameters are the same as in Example 1.

[0116] (1) Prepare cinnamon essential oil@chitosan microcapsules and DA bond semi-interpenetrating self-healing network solution by following steps (1)-(5) of Example 1.

[0117] (2) Mix the microcapsules at a mass ratio of “1g microcapsule + 5.7g DA bond semi-interpenetrating self-healing network solution” (1g:6.7g≈15%) and stir at 300rpm for 30min to obtain a non-specific ratio mixture.

[0118] (3) Preparation of individual films for testing: Take the above non-specific ratio mixture and coat it evenly on a horizontally placed polytetrafluoroethylene template (size 100mm×150mm). Control the coating amount to 400g / m² and cure at 60℃ for 6h. After curing, peel off the template to obtain an independent non-specific ratio composite film (thickness about 0.1mm) for subsequent performance testing.

[0119] (4) Verification of wood surface coating: Take another portion of the mixture and apply it to pine wood using the coating process described in Example 1 (coating amount 400g / m²). 2 (Cure at 60℃ for 6 hours) for functional effect verification.

[0120] 2. Performance Testing

[0121] Tensile strength recovery rate test: Referring to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", a standard specimen, Type 5, with a total length of 130 mm and a film thickness equal to the actual thickness after curing, was prepared first. The original tensile strength was tested (21.5 ± 1.3 MPa). A notch was made in the center of the specimen's length direction using a single-edged blade. The notch width was 0.2 mm, the depth was 1 / 2 the film thickness (approximately 0.05 mm), and the length was 5 mm (parallel to the specimen width direction). The notched specimen was placed in an 80℃ constant temperature oven for 2 hours for repair. After cooling to room temperature, the tensile strength was tested again using a universal testing machine (11.0 ± 0.9 MPa). The tensile strength recovery rate was calculated using the formula "Recovery rate = (Repaired strength / Original strength) × 100%", resulting in (11.0 / 21.5) × 100% ≈ 51.3 ± 1.9%.

[0122] Microcapsule dispersibility test: The cross-section of the film was observed by SEM (M360-HK822, Shenzhen Ausmicro Optical Instrument Co., Ltd.), and the diameter of the aggregates was counted using Image-Pro Plus software. More than 90% of the aggregates had a diameter >50μm.

[0123] 3. Performance data of Comparative Example 3

[0124] Test item E. coli S. aureus Tensile strength recovery rate Microcapsule dispersibility Inhibition zone diameter (mm) 14.2±0.3 15.0±0.2 51.3±1.9% Agglomeration is severe (> 50㎛) 7-day antibacterial rate (%) 68.5±2.0 72.1±1.7 - -

[0125] 4. Conclusion

[0126] Excessive use of microcapsules leads to aggregation, damage to the DA bond network, a sharp drop in self-repair rate, and impairment of both antibacterial and self-repair capabilities.

[0127] Comparative Example 4: Direct mixing of unencapsulated cinnamon essential oil (10% essential oil, no chitosan)

[0128] 1. Formulation and Preparation Process

[0129] The preparation process of Comparative Example 4 is basically the same as that of Example 1, except that the chitosan encapsulation step is omitted, and cinnamon essential oil is directly mixed into the DA bond semi-interpenetrating self-healing network solution, with the amount adjusted to 10%. All other process parameters are the same as those in Example 1.

[0130] (1) Without Example 1, steps (1)-(4) are used. Take 6g of cinnamon essential oil directly (the amount of core material used is the same as in Example 1).

[0131] (2) Follow the steps (5) of Example 1 to prepare a DA bond semi-interpenetrating self-healing network solution.

[0132] (3) Add 6g of cinnamon essential oil (without chitosan encapsulation) to 54g of DA bond semi-interpenetrating self-repairing network solution, stir at 1200rpm for 30min to form a mixed solution (essential oil content 10%).

[0133] (4) Preparation of individual films for testing: Take the above mixed solution and coat it evenly on a horizontally placed polytetrafluoroethylene template (size 100mm×150mm). Control the coating amount to 400g / m² and cure at 60℃ for 6h. After curing, peel off the template to obtain an independent direct mixed composite film (thickness about 0.1mm) for subsequent performance testing.

[0134] (5) Verification of wood surface coating: Take another mixed solution and apply it to pine wood using the coating process in Example 1 (coating amount 400 g / m²), cure at 60℃ for 6 hours, and use it to verify the functional effect.

[0135] 2. Performance Testing

[0136] Tensile strength recovery rate test: Referring to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", a standard specimen, Type 5, with a total length of 130 mm and a film thickness equal to the actual thickness after curing, was prepared first. The original tensile strength was tested (23.8 ± 1.4 MPa). A notch was made in the center of the specimen's length direction using a single-edged blade, with a notch width of 0.2 mm, a depth of 1 / 2 the film thickness (approximately 0.05 mm), and a length of 5 mm (parallel to the specimen's width direction). The notched specimen was placed in an 80℃ constant temperature oven for 2 hours for repair. After cooling to room temperature, the tensile strength was tested again using a universal testing machine (14.9 ± 1.1 MPa). The tensile strength recovery rate was calculated using the formula "Recovery rate = (Repaired strength / Original strength) × 100%", resulting in a recovery rate of approximately 62.5 ± 2.1% (14.9 / 23.8) × 100%.

[0137] 7-day essential oil retention test: According to the solvent extraction method of GB / T 21866-2008, the residual amount of essential oil after 7 days was only 12.3% of the initial content, because there was no chitosan encapsulation and the essential oil completely evaporated.

[0138] 3. Performance data for Comparative Example 4

[0139] Test item E. coli S. aureus Tensile strength recovery rate 7-day essential oil retention rate Inhibition zone diameter (mm) 13.5±0.2 14.3±0.3 62.5±2.1% 12.3% 7-day antibacterial rate (%) 35.2±1.6 40.1±1.9 - -

[0140] 4. Conclusion

[0141] Essential oils evaporate directly, resulting in poor long-lasting antibacterial effects. Furthermore, the oil phase damages the polymer network, leading to a lower self-repair rate compared to the preferred system.

[0142] Relevant performance tests in Examples 1-4

[0143] Tensile strength recovery rate test: Referring to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", a standard sample was first prepared. The DA bond semi-interpenetrating self-healing network solution from Examples 1-4 was uniformly coated onto a horizontally placed polytetrafluoroethylene template (size 100mm×150mm), and the coating amount was controlled at 400g / m². 2The sample was cured at 60℃ for 6 hours. After curing, an independent simple DA bond semi-interpenetrating network polymer film (approximately 0.1 mm thick) was peeled off from the template and then cut into Type 5 samples with a total length of 130 mm. Examples 1-4: Original tensile strength 31.8-33.7 MPa; A notch was made in the center of the sample length direction using a single-edged blade, with a notch width of 0.2 mm, a depth of 1 / 2 the film thickness (approximately 0.05 mm), and a length of 5 mm (parallel to the sample width direction); The notched sample was placed in an 80℃ constant temperature oven for 2 hours for repair. After cooling to room temperature, the tensile strength was tested again using a universal testing machine and found to be 29.2-31.7 MPa. The recovery rate was calculated to be 91.7-94.2% according to the formula.

[0144] 7-day essential oil retention test: According to the solvent extraction method of GB / T 21866-2008, the residual amount of essential oil in Examples 1-4 after 7 days was determined by gas chromatography to be 75.9-78.2% of the initial content. Due to the chitosan encapsulation + DA network barrier, the retention rate was significantly higher than that of each control group.

[0145] Mechanical strength test: Same as GB / T 1040.3-2006, dumbbell-shaped standard specimens (Type 5, conforming to the special specimen type for films / sheets in the national standard) were used. The tensile strength of Examples 1-4 was 31.8-33.7 MPa, and the elongation at break was 18.5-20.2%. Due to the synergistic effect of microcapsules and polymer network, the strength was increased by 12-18% compared with simple DA polymer (Comparative Example 2).

[0146] Microcapsule dispersibility test: SEM was used to observe the film cross-section, and Image-Pro Plus software was used for statistical analysis. The diameter of the microcapsule aggregates in Examples 1-4 was ≤10μm, and the dispersion uniformity met the requirements of "dispersion uniformity of functional fillers" in GB / T 1735-2009 "Determination of thickness of paints and varnishes".

[0147] Performance data of Examples 1-4

[0148] Test item Example 1 Example 2 Example 3 Example 4 E. coli inhibition zone diameter (mm) 18.6±0.3 18.9±0.2 17.8±0.3 19.5±0.2 S. aureus inhibition zone diameter (mm) 19.2±0.2 19.5±0.3 18.5±0.2 20.1±0.3 7-day E. coli antibacterial rate (%) 91.3±1.2 92.1±1.0 90.5±1.3 93.5±1.0 7-day S. aureus antibacterial rate (%) 92.8±1.0 93.2±0.9 91.7±1.1 94.3±0.8 Tensile strength recovery rate (%) 92.1±1.8 93.5±1.5 91.7±1.6 94.2±1.4 7-day essential oil retention rate (%) 76.8±1.5 77.5±1.3 75.9±1.6 78.2±1.2 Mechanical strength (MPa) 32.4±1.5 33.1±1.4 31.8±1.6 33.7±1.3

[0149] Synergistic effect analysis

[0150] Quantitative data from Comparative Examples 1-4 and Examples 1-4 clearly show a significant bidirectional synergistic effect between cinnamon essential oil@chitosan microcapsules and the DA bond semi-interpenetrating self-healing network polymer. This is not a simple superposition of the two functions, but rather a triple optimization of "antibacterial-self-healing-mechanical properties," as detailed below:

[0151] (1) Self-healing polymer network enhances the antibacterial efficacy of cinnamon essential oil

[0152] In Examples 1-4, the essential oil retention rate reached 75.9%-78.2% after 7 days, which is more than 97% higher than that of the simple chitosan-encapsulated microcapsule film (Comparative Example 1, 38.5%), and more than 5 times higher than that of the unencapsulated direct mixing system (Comparative Example 4, 12.3%). The core reason is that the dense structure of the DA bond semi-interpenetrating network provides a physical barrier for the microcapsules, slowing down the volatilization and oxidation of cinnamon essential oil. At the same time, the pH responsiveness of the chitosan wall material and the interfacial interaction of the polymer network work synergistically to achieve "on-demand release" of essential oil, so that the antibacterial rate is still maintained at 90.5%-93.5% (Escherichia coli) and 91.7%-94.3% (Staphylococcus aureus) after 7 days, while the antibacterial rate of Comparative Example 1 is only 52.1%-58.3% after 7 days.

[0153] (2) Cinnamon essential oil@chitosan microcapsules enhance the comprehensive properties of self-healing network polymers

[0154] The tensile strength recovery rates of Examples 1-4 reached 91.7%-94.2%, which is 17%-20% higher than that of the simple DA bond semi-interpenetrating network polymer (Comparative Example 2, 78.2%), and 79%-84% higher than that of the microcapsule excess system (Comparative Example 3, 51.3%). The key mechanism is that the amino groups in the chitosan molecule form hydrogen bonds with the DA polymer segments, which lowers the activation energy of DA bond recombination and accelerates the reversible DA reaction. At the same time, the addition of 7% microcapsules did not damage the polymer network structure, and the crosslinking density ratio was maintained in the optimal range of 0.4, ensuring the efficiency of chemical bond reconstruction at the damaged sites.

[0155] The tensile strength of Examples 1-4 reached 31.8-33.7 MPa, and the elongation at break was 18.5-20.2%, which were 12%-18% and 21%-32% higher than those of pure DA polymer (Comparative Example 2, 28.6 MPa, 15.3%), respectively. This is because the cinnamon oil@chitosan microcapsules, as a rigid dispersed phase, are uniformly dispersed in the pores of the polymer network (aggregate diameter ≤10 μm), forming a "rigid-flexible complementary" structure with the flexible DA bond network. This not only fills the network defects but also enhances the structural support, solving the technical contradiction of traditional self-healing materials in balancing "repairability" and "mechanical strength".

[0156] (3) The uniqueness and irreplaceability of synergistic effects

[0157] The aforementioned synergistic effect can only be achieved when the following conditions are met: "7% chitosan-encapsulated cinnamon essential oil microcapsules + 93% DA-bonded semi-interpenetrating self-healing network polymer, i.e., the mass ratio of microcapsules to DA-bonded semi-interpenetrating self-healing network solution is 1:13".

[0158] If the chitosan encapsulation is removed (Comparative Example 4), the essential oil evaporates rapidly, resulting in the loss of its long-lasting antibacterial effect. Furthermore, the oil phase damages the polymer network, causing the self-repair rate to drop to 62.5%.

[0159] If the microcapsules are in excessive amounts (Comparative Example 3, 15% content), they will cause aggregation (aggregate diameter > 50 μm), destroy the DA bond cross-linking network, and the self-repair rate will drop sharply by 51.3%. The antibacterial efficiency will also be limited due to the uneven release of essential oils caused by aggregation.

[0160] Without the DA polymer network (Comparative Example 1), only short-term antibacterial effect can be achieved, without self-repair function, and the essential oil retention rate is less than 40% after 7 days.

[0161] This invention discloses a method for preparing a DA-bonded polymer film with both antibacterial and self-healing functions for use on wood surfaces. The required raw materials include cinnamon oil, chitosan, acetic acid, deionized water, Tween 80, sodium tripolyphosphate (STPP), bisphenol A diglycidyl ether (DGEBA), furfuryl alcohol (FA), triethylamine (TEA), bismaleimide (BMI), tetrahydrofuran (THF), and 4,4-diaminodiphenylmethane (DDM). First, using chitosan as the wall material and cinnamon oil as the core material, cinnamon oil@chitosan antibacterial microcapsules are prepared through emulsification, crosslinking, and spray drying to achieve controlled release of the essential oil. Then, using DGEBA and FA as raw materials, furanyl functionalized epoxy resin (FFER) is prepared under TEA catalysis. BMI is added, and a DA-bonded self-healing polymer is prepared through a DA reaction. Finally, DDM is added to the system, and it continues to react with excess DGEBA to generate a crosslinked polymer network. Finally, the microcapsules are added to a DA-bonded semi-interpenetrating self-healing network solution in a specific ratio, brushed onto the wood, and cured to form a film. This film has both antibacterial and self-healing functions, can repair scratches and microcracks on the wood surface, inhibit microbial erosion, uses environmentally friendly raw materials, and is easily industrialized. It is suitable for the protection of high-end furniture, wood flooring, and other wood products, and can extend the service life of wood products.

[0162] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection of this invention is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.

Claims

1. A DA-bonded polymer for use on wood surfaces, possessing both antibacterial and self-healing functions, characterized in that, The ingredients include the following parts by weight: 5-12 parts by weight of cinnamon essential oil, 3-8 parts by weight of chitosan, 0.3-0.55 parts by weight of acetic acid, 20-45 parts by weight of deionized water, 1-3 parts by weight of Tween 80, 1-3 parts by weight of sodium tripolyphosphate (STPP), 15-22 parts by weight of bisphenol A diglycidyl ether (DGEBA), 3.8-5.7 parts by weight of furfuryl alcohol (FA), 0.3-0.5 parts by weight of triethylamine (TEA), 17-24 parts by weight of bismaleimide (BMI), 2.5-4.5 parts by weight of 4,4-diaminodiphenylmethane (DDM), and 140-160 parts by weight of tetrahydrofuran (THF).

2. The DA-bonded polymer for wood surfaces with both antibacterial and self-healing functions according to claim 1, characterized in that, The ingredients include the following parts by weight: 6-10 parts by weight of cinnamon essential oil, 4-6 parts by weight of chitosan, 0.35-0.5 parts by weight of acetic acid, 30-40 parts by weight of deionized water, 1.5-2.5 parts by weight of Tween 80, 1.5-2.5 parts by weight of STPP, 17-20 parts by weight of DGEBA, 4-5.5 parts by weight of FA, 0.4-0.45 parts by weight of TEA, 18-23 parts by weight of BMI, 3-4 parts by weight of DDM, and 145-155 parts by weight of THF.

3. The method for preparing the DA-bonded polymer with both antibacterial and self-healing functions for wood surfaces as described in claim 1, characterized in that, Includes the following steps: (1) Dissolve an appropriate amount of acetic acid in deionized water, then weigh an appropriate amount of chitosan and add it to the acetic acid solution. Mix the mixture using a magnetic stirrer and react for a period of time to obtain a wall material chitosan solution. (2) Add emulsifier Tween80 to deionized water and mix evenly. Add cinnamon essential oil dropwise and emulsify using a magnetic stirring device. After emulsifying for a period of time, sonicate and emulsify for another period of time to obtain a uniformly dispersed core material emulsion. (3) Place the core material emulsion in a magnetic stirring device, and then slowly add the wall material chitosan solution, controlling the dropping speed to ensure full contact with the core material emulsion. Maintain the pH of the system by adding acetic acid, and microencapsulate for a period of time to obtain cinnamon oil@chitosan solution; weigh STPP into deionized water, add it dropwise to the cinnamon oil@chitosan solution, and cross-link for a period of time. (4) After the cross-linking reaction, the cinnamon essential oil@chitosan solution was left to stand for a long time and then spray-dried using a spray dryer; the powder in the spray dryer was collected to obtain cinnamon essential oil@chitosan microcapsules; (5) Add DGEBA and FA to a beaker, add THF and TEA, mix with a magnetic stirrer, stir for a period of time to obtain furanyl functionalized epoxy resin FFER; then add BMI, add an appropriate amount of THF as a solvent, heat and stir for a period of time to obtain DA bond self-healing polymer solution; then add DDM, continue stirring for a period of time, and use the excess DGEBA to react with DDM to form DA bond semi-interpenetrating self-healing network solution; (6) Add an appropriate amount of microcapsules to the DA bond semi-interpenetrating self-healing network solution according to the proportion, mix and stir to obtain a DA bond polymer with both antibacterial and self-healing functions for use on wood surfaces.

4. The method for preparing a DA-bonded polymer with both antibacterial and self-healing functions for wood surfaces according to claim 3, characterized in that, In step (1), acetic acid and deionized water are mixed to prepare an acidic solution. The temperature of the magnetic stirrer is set to 45°C and the rotation speed is 600 rpm. The reaction time is 1 h to ensure that the chitosan is completely dissolved and a uniform and transparent chitosan solution for wall material is formed.

5. The method for preparing a DA-bonded polymer with both antibacterial and self-healing functions for wood surfaces according to claim 3, characterized in that, In step (2), emulsification is carried out in a water bath. The water bath temperature is set to 45℃ and the rotation speed is 1200 rpm. Emulsification is carried out for 1 hour, followed by ultrasonication for 10 minutes and then emulsification for 30 minutes. The ultrasonic power is 300-500 W to ensure that the cinnamon essential oil is fully emulsified to form a core material emulsion with uniform particle size distribution.

6. The method for preparing a DA-bonded polymer with both antibacterial and self-healing functions for wood surfaces according to claim 3, characterized in that, In step (3), the dropping rate of the chitosan solution is controlled at 1-2 drops / second, the pH of the system is maintained between 3.8 and 4.0, and the microencapsulation time is 1 h; sodium tripolyphosphate (STPP) is dissolved in deionized water at a mass ratio of 1:3-1:9, the crosslinking reaction temperature is room temperature (25±2℃), and the reaction time is 3 h, to ensure the formation of a structurally stable cinnamon oil@chitosan microcapsule precursor.

7. The method for preparing a DA-bonded polymer with both antibacterial and self-healing functions for wood surfaces according to claim 3, characterized in that, In step (4), the inlet air temperature of the spray dryer is set to 110℃, the feeding rate is 200 mL / h, the particle size of the collected microcapsule powder is controlled to be 3-10 μm, and the microcapsule coating rate is ≥80%.

8. The method for preparing a DA-bonded polymer with both antibacterial and self-healing functions for wood surfaces according to claim 3, characterized in that, In step (5), the mass ratio of DGEBA to FA in the first step is 3.5:1-5.5:1, and the initial addition of THF is 50 g. When preparing furanyl functionalized epoxy resin FFER, the temperature of the magnetic stirrer is 65℃ and the stirring time is 5 h until the solution is viscous and clear. After adding BMI, 100 g of THF is added, the heating temperature is 65℃ and the stirring time is 40 min to ensure that the DA reaction is fully carried out. After adding DDM, the temperature is raised to 60℃ and the stirring time is 1.5 h to allow the excess DGEBA to react completely with DDM, and finally form a DA bond semi-interpenetrating self-healing network solution with a "DA bond linear network - epoxy resin crosslinking network" semi-interpenetrating structure.

9. The method for preparing a DA-bonded polymer with both antibacterial and self-healing functions for wood surfaces according to claim 3, characterized in that, In step (6), the mass ratio of the microcapsules to the DA bond semi-interpenetrating self-healing network solution is 1:13, and the microcapsules are uniformly dispersed during stirring.

10. A method of using the DA-bonded polymer prepared according to the preparation method of claim 3, characterized in that: The DA-bonded polymer was applied to the wood surface by brushing, and the coating was formed after drying and curing. The coating amount was controlled at 400 g / m², the drying and curing temperature was 60℃, and the curing time was 6 h.

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