Photopolymerized organic silicon self-repairing antibacterial coating based on hydrogen bond and construction method

Abstract

The present invention discloses a hydrogen-bonded photopolymerized organosilicon self-healing antibacterial coating and a construction method, which relates to the technical field of antibacterial coatings. The technical points are as follows: first, an isocyanate-terminated polydimethylsiloxane is synthesized, and urea hydrogen bonds are introduced into the structure. Then, an acryloyloxy-terminated polydimethylsiloxane with photocuring activity is synthesized by further reaction of the isocyanate group and the hydroxyl group, and hydrogen bonds and acryloyloxy groups are introduced into the organosilicon structure. Trimethylolpropane triacrylate (TMPTA) is used as a cross-linking agent, and an acryloyloxy free radical polymerization reaction is initiated under the action of ultraviolet light based on a free radical polymerization mechanism to form a covalently cross-linked network structure. By utilizing the interaction of cross-linked hydrogen bonds, the system is endowed with the ability to heal; and by controlling the photocuring reaction conditions, polymerization degree and cross-linking agent content, the mechanical properties and self-healing properties of the material are regulated and optimized, and the antibacterial properties of the coating are explored.

Description

Technical Field

[0001] The present invention relates to the technical field of antibacterial coatings, and in particular to a hydrogen-bond-based photopolymerized organosilicon self-repairing antibacterial coating and a construction method thereof. Background Art

[0002] Plants, animals and microorganisms that live in the ocean for a long time attach to the surface of marine warships and other marine equipment, causing damage to the equipment and seriously affecting the performance of the ship, such as slowing down the hull, increasing fuel consumption, increasing greenhouse gas emissions and inducing or promoting corrosion of metal or concrete structures. Coatings containing tributyltin are the most effective system to combat marine biofouling, but due to their persistent toxicity to marine organisms, their use has been banned worldwide since 2008. Among the many methods for preventing and controlling marine biofouling, marine antifouling coatings are currently one of the most economical and effective strategies to solve the problem of marine biofouling. However, in order to ensure the antifouling effect of the coating, the currently commonly used antifouling coatings contain diffusive antifouling agents such as cuprous oxide. The release of these antifouling agents into the marine environment seriously threatens the marine ecological environment. It is of great significance to construct an environmentally friendly and non-toxic bulk antifouling and antibacterial coating.

[0003] The most commonly used material in antifouling and antibacterial materials is silicone elastomer, especially poly (dimethylsiloxane) (PDMS) elastomer. Due to its Si-O-Si molecular structure, PDMS has excellent properties such as low surface energy, weather resistance, chemical corrosion resistance, safety and non-toxicity, so that it can remain stable in the marine environment and is widely used as a protective material in the field of marine antifouling and antibacterial. However, due to the relatively soft main chain and low surface energy of the silicone molecular structure, this type of material has exposed a series of shortcomings in actual use: 1) poor mechanical properties, easy to be cut, torn, punctured and other mechanical damage, and cannot be repaired after damage, thus reducing its service life; 2) poor antibacterial performance.

[0004] In addition, silicone materials are usually cured by heat, but heat curing has a high curing temperature, a long curing time, and high energy consumption. Photocuring can compensate for this shortcoming. Compared with heat curing, photocuring can complete curing at room temperature or even below room temperature, while shortening the curing time. It has huge advantages over the application of traditional single-functional monomer curing and multi-functional monomer curing. Therefore, designing silicone antibacterial materials with good mechanical properties and self-healing properties based on photocuring technology is one of the key development contents in this field. Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems and provide a hydrogen bond-based photopolymerized silicone self-healing antibacterial coating and a construction method.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows: a hydrogen-bonded photopolymerized organosilicon self-healing antibacterial coating, the coating comprising:

[0007] a. Silicone molecular structure: acryloxy-terminated polydimethylsiloxane (PDMS-IU-DA);

[0008] b. Cross-linking agent: TMPTA;

[0009] c. Photoinitiator: diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO).

[0010] The present invention further provides a method for preparing the coating comprising the following steps:

[0011] S1. Synthesis of an organosilicon molecular structure with hydrogen bond forming ability: acryloxy-terminated polydimethylsiloxane (PDMS-IU-DA);

[0012] S2. Adding a photopolymer to form hydrogen bonds: using the organosilicon molecular structure in step S1 as the main body, TMPTA as the crosslinking agent, and TPO as the photoinitiator;

[0013] S3. Curing the mixture under light conditions to form a coating.

[0014] The present invention further discloses an acryloxy-terminated polydimethylsiloxane synthesis process described in step S1, wherein bis(3-aminopropyl)-terminated polydimethylsiloxane (H2N-PDMS-NH2), isophorone diisocyanate (IPDI) and 2-hydroxyethyl acrylate are selected as raw materials, and a series of acryloxy-terminated organosilicon oligomers (PDMS-IU-DA) are synthesized by polycondensation reaction, which are connected by isophorone diurea units (IU units) to introduce urea hydrogen bonds into the system.

[0015] Furthermore, in the present invention, in step S3, the lighting condition includes ultraviolet light.

[0016] Compared with the existing technology, this solution has the following beneficial effects:

[0017] Antibacterial properties: The coating has good antibacterial properties, which can effectively inhibit the growth and reproduction of microorganisms, reduce the contamination and adhesion of bacteria, mold and other microorganisms to the coating surface, thereby achieving the antibacterial purpose.

[0018] Self-healing properties: The cross-linked hydrogen bonds in the coating can reconnect when damaged, giving the coating the ability to self-repair. When the coating surface is scratched or slightly damaged, the cross-linked hydrogen bonds can reform, repairing the coating's integrity and extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the structural design of the acryloxy-terminated polydimethylsiloxane in the embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the photopolymerization process of the organosilicon system in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0022] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0023] Example:

[0024] like Figure 1-2 As shown, a hydrogen-bond-based photopolymerized organosilicon self-healing antibacterial coating and a construction method thereof include:

[0025] (1) Design and synthesis of functionalized organosilicon molecular structures

[0026] The present invention intends to construct a photocurable silicone structure containing strong and weak hydrogen bonds. First, bis(3-aminopropyl)-terminated polydimethylsiloxane (H2N-PDMS-NH2), isophorone diisocyanate (IPDI) and 2-hydroxyethyl acrylate are selected as raw materials, and a series of acryloxy-terminated silicone oligomers (PDMS-IU-DA) are synthesized by polycondensation reaction. The urea hydrogen bonds are introduced into the system through isophorone diurea units (IU units). Figure 1 A schematic diagram of the synthesis route is given, and the molecular structure of the synthesized target product is analyzed and characterized using FTIR and NMR.

[0027] (2) Construction of photocurable silicone coating and study of the photocuring process

[0028] like Figure 2As shown in the figure, a photocurable organosilicon polymerization system was constructed using a series of PDMS-IU-DA as the main component, TMPTA as the crosslinker, and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as the photoinitiator. The photocuring process was monitored by FTIR, the carbon-carbon double bond content was calculated, and the final double bond conversion rate was determined. The influence of the degree of polymerization on the polymerization system during the curing process was investigated, and the influence of the reaction degree and crosslinking density on the photocuring process was established. By adjusting the crosslinker and photoinitiator content and reaction conditions (such as light intensity), the polymerization system was rapidly controlled, and the influence of these on the polymerization system's performance was explored.

[0029] (3) Performance research and regulation of photocurable silicone coatings

[0030] ①Structural control and performance evaluation of photocurable silicone materials

[0031] The performance regulation of photocurable silicone materials is based on the following points: 1) by adjusting the IU segment in the chain segment during the synthesis of PDMS-IU-DA; 2) by adjusting the curing conditions (photoinitiator content, photocuring time); 3) by adjusting the TMPTA content in the polymerization system. The presence of hydrogen bonds in the system can give the coating self-healing ability, allowing it to restore its basic properties after damage. The self-healing process is studied and analyzed using an optical microscope, and the mechanical properties before and after self-healing under different conditions are studied using an electronic universal tensile machine, and the repair efficiency is calculated. The glass transition temperature of the material is determined by DSC and DMA, and the surface properties of the silicone coating are evaluated by water contact angle and surface free energy.

[0032] Using PDMS-IU-MA as the primary raw material and the crosslinker TMPTA as the primary raw material, we selected five TMPTA content systems: 3%, 6%, 10%, 15%, and 20%. Specifically, a mixture of PDMS-IU-MA, TMPTA, and a photoinitiator was stirred evenly, poured into a polyfluoroethylene mold, and irradiated with a UV LED curing lamp (365nm, 40W). The mixture of PDMS-IU-MA and 3wt% TMPTA was designated PDMS-IU-MA-3%, and the other solutions were similarly labeled.

[0033] Performance analysis of each system revealed that increasing TMPTA content increased the tensile strength of the silicone system. This is due to the free radical polymerization of acryloyloxy groups under light, forming a covalent crosslinked network. However, increasing TMPTA content in the system also decreased the self-healing properties of the system.

[0034] We fixed the TMPTA content and explored the effect of light curing time on tensile properties. The results showed that the performance requirements can be achieved after 2 minutes of light exposure. As the light exposure time continued to increase, the tensile strength decreased.

[0035] (4) Research on antifouling and antibacterial applications of photocurable silicone coating materials

[0036] Study on the Antifouling and Antibacterial Properties of Silicone Coatings

[0037] To evaluate the antibacterial properties of this self-healing silicone coating, experiments were conducted using Staphylococcus aureus and Escherichia coli. The bacterial adhesion patterns on the coating surface were compared, thereby analyzing the material's antibacterial performance. The effects of molecular structure and immersion time on the density of diatom attachment on the coating surface were investigated to assess the antifouling and antibacterial capabilities of the antimicrobial coating. Comparative experiments were conducted using the traditional Sylgard 184 material.

[0038] Antibacterial test

[0039] The shake flask method is a common method for evaluating antimicrobial activity. In this study, we used two typical bacterial strains for quantitative analysis: Staphylococcus aureus and Escherichia coli. Single colonies of each strain were cultured in broth at 37°C and 120 rpm for 18 hours. The bacterial suspension was then diluted with a specific volume of LB medium to create a new suspension. This suspension was then concentrated using a concentration corresponding to 10-8 colony-forming units (CFU / mL) to approximate bacterial concentration.

[0040] Blank group:

[0041] A 1g sample of the PDMS and IPDI control components was placed in a test tube containing 200µl of the diluted bacterial suspension and 15ml of broth and incubated in a shaker at 37°C and 120 rpm for 24 hours. After 24 hours, the bacterial suspension, diluted 106 times, was spread on an agar plate and incubated in a 37°C incubator for 24 hours.

[0042] Experimental group:

[0043] The modified samples containing different proportions of TMPTA were diluted to the same multiple as the control samples of the same mass, and the number of surviving colonies was observed as in the blank group. The bacteriostasis rate (BR) of the bacteria was then calculated as follows: BR = (BA) / B × 100%

[0044] Where A is the number of viable microorganisms on the agar plate in the experimental group, and B is the number of viable bacteria on the agar plate in the blank group. All colony count samples were sterilized under UV light for at least 30 minutes before operation. All items were placed in an autoclave and sterilized at 121°C for 30 minutes, and the culture medium was sterilized for 30 minutes. The entire process was performed on a clean bench.

[0045] Experimental results:

[0046] Staphylococcus aureus

[0047] The 0% sample represents the blank control, with a Staphylococcus aureus colony count of 374. The total colony counts for the other modified samples containing varying TMPTA ratios were: 172 for the 3% sample, 127 for the 6% sample, 106 for the 10% sample, 80 for the 15% sample, and 46 for the 20% sample. The bacterial inhibition rate (BR) was calculated using the formula BR = (BA) / B × 100%, yielding the following results:

[0048] Improved product containing 3% TMPTA: BR = (374-172) / 374 × 100% = 54.01%

[0049] Improved product containing 6% TMPTA: BR = (374-127) / 374 × 100% = 66.04%

[0050] Improved product containing 10% TMPTA: BR = (374-106) / 374×100% = 71.66% Improved product containing 15% TMPTA: BR = (374-80) / 374×100% = 78.61%

[0051] Improved product containing 20% ​​TMPTA: BR = (374-46) / 374 × 100% = 87.70%

[0052] From the experimental data, it can be seen that the more TMPTA the improved sample contains, the higher the antibacterial rate is, that is, the more TMPTA the improved sample contains, the more obvious the antibacterial effect on Staphylococcus aureus is.

[0053] Escherichia coli

[0054] The 0% sample represents the blank group, with a colony count of 303 E. coli. The total colony counts for the other modified samples containing varying TMPTA ratios were: 174 for the 3% sample, 92 for the 6% sample, 50 for the 10% sample, 30 for the 15% sample, and 22 for the 20% sample. The bacterial inhibition rate (BR) was calculated using the formula BR = (BA) / B × 100%, yielding the following results:

[0055] Improved product containing 3% TMPTA: BR = (303-174) / 303 × 100% = 42.57%

[0056] Improved product containing 6% TMPTA: BR = (303-92) / 303 × 100% = 69.64%

[0057] Improved product containing 10% TMPTA: BR = (303-50) / 303 × 100% = 83.50%

[0058] Improved product containing 15% TMPTA: BR = (303-30) / 303 × 100% = 90.10%

[0059] Improved product containing 20% ​​TMPTA: BR = (303-22) / 303 × 100% = 92.74%

[0060] From the experimental data, it can be seen that the more TMPTA the modified sample contains, the higher the antibacterial rate is, that is, the more TMPTA the modified sample contains, the more obvious the antibacterial effect on Escherichia coli is.

[0061] The above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the embodiments as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A hydrogen-bonded photopolymerized organosilicon self-healing antibacterial coating, characterized in that: The coating includes: a. Silicone molecular structure: acryloxy-terminated polydimethylsiloxane PDMS-IU-DA; b. Cross-linking agent: TMPTA; c. Photoinitiator: diphenyl 2,4,6-trimethylbenzoylphosphine oxide TPO; The synthesis of the acryloxy-terminated polydimethylsiloxane is to select bis(3-aminopropyl)-terminated polydimethylsiloxane H2N-PDMS-NH2, isophorone diisocyanate IPDI and 2-hydroxyethyl acrylate as raw materials for polycondensation reaction, and introduce urea hydrogen bonds into the system.

2. The method for constructing a hydrogen bond-based photopolymerized organosilicon self-healing antibacterial coating according to claim 1, wherein: The following steps are involved: S1. Synthesis of an organosilicon molecular structure with hydrogen bond forming ability: acryloxy-terminated polydimethylsiloxane PDMS-IU-DA; S2. Adding a photopolymer to form hydrogen bonds: using the organosilicon molecular structure in step S1 as the main body, TMPTA as the crosslinking agent, and TPO as the photoinitiator; S3. Curing the mixture under light conditions to form a coating.

3. The method for constructing a hydrogen-bond-based photopolymerized organosilicon self-healing antibacterial coating according to claim 2, wherein: In step S3, the lighting condition includes ultraviolet light.

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