Polyurethane with efficient electromagnetic shielding and photo-thermal repairability and preparation method

Abstract

The invention discloses polyurethane with efficient electromagnetic shielding and photo-thermal repairability and a preparation method, and belongs to the technical field of electromagnetic shielding materials.The method comprises the steps that amino-modified triphenyl boroxane is dissolved in an organic solvent, and an amino-modified triphenyl boroxane solution is obtained; mixing and stirring with an isocyanate-based polyurethane prepolymer, and carrying out chain extension reaction, so as to prepare a self-repairing polyurethane prepolymer; the preparation method comprises the following steps: adding a hydroxylated carbon nanotube suspension liquid and a nano-silver suspension liquid, stirring and reacting to obtain a cross-linked blended solution, and sequentially carrying out mold reversing and drying on the cross-linked blended solution to obtain the polyurethane with efficient electromagnetic shielding and photo-thermal repairability. The boron-oxygen bond enables the polyurethane film to realize self-repairing under the action of water molecules. The hydroxylated carbon nanotubes and the nano-silver endow the polyurethane film with good electromagnetic shielding performance, photo-thermal conversion performance and antibacterial property. The preparation route is simple, the service life of the electromagnetic shielding material is prolonged, and a thought is provided for design and manufacturing of a multifunctional flexible wearable material.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic shielding materials, and specifically relates to a polyurethane with high-efficiency electromagnetic shielding and photothermal repairability and a preparation method thereof. Background Art

[0002] Polymer-based electromagnetic shielding materials, due to their advantages over traditional metal electromagnetic shielding materials, such as light weight, flexibility, corrosion resistance, and ease of processing, have shown broad application prospects in aerospace, wearable electronic devices, 5G communications, and other fields. However, the durability and environmental stability of polymer-based electromagnetic shielding materials still face challenges: long-term mechanical deformation may lead to fractures in the conductive network, scratches, cracks on the material surface, and other defects, which may seriously affect the overall electromagnetic shielding effectiveness of the material, forcing scholars to focus on the research and preparation of self-healing electromagnetic shielding composite materials.

[0003] Currently, the self-healing mechanisms of polymer materials can be categorized as either externally assisted or intrinsic, depending on the presence of external repair agents and the design of dynamic chemical bonds. Externally assisted self-healing materials rely on microcapsules containing repair agents, resulting in slow dynamic response and difficulty repairing the same location multiple times. Intrinsic self-healing, based on the ability of the material's internal reversible dynamic chemical bonds to break and recombine, such as disulfide bonds, acylhydrazone bonds, and hydrogen bonds, eliminates the need for additional repair agents. However, self-healing relies on harsh environments such as strong acids, strong bases, and high temperatures, and remains unsatisfactory in the self-healing of electromagnetic shielding materials.

[0004] Therefore, in order to address the problems of extreme repair environment, repair efficiency and attenuation of electromagnetic shielding effectiveness of existing intrinsic self-repairing electromagnetic shielding materials after self-repair, it is urgent to find a new self-repairing component that has a mild self-repairing environment and high self-repairing ability, and can still maintain a certain structural stability after multiple damages, thereby extending the service life of the electromagnetic shielding material. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a polyurethane with high-efficiency electromagnetic shielding and photothermal repairability and a preparation method, so as to solve the technical problem of complex repair conditions of existing damaged electromagnetic shielding materials.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability, comprising the following steps: 1) dissolving amino-modified triphenylboroxine in an organic solvent to obtain an amino-modified triphenylboroxine solution, and then mixing and stirring the solution with an isocyanate-based polyurethane prepolymer to perform a chain extension reaction to obtain a self-healing polyurethane prepolymer; 2) Adding a hydroxylated carbon nanotube suspension and a nanosilver suspension to a self-healing polyurethane prepolymer, stirring and reacting to obtain a cross-linked blend solution, and then sequentially casting and drying the cross-linked blend solution to obtain a polyurethane with high-efficiency electromagnetic shielding and photothermal repairability.

[0007] Preferably, the amino-modified triphenylboroxine has the structural formula: .

[0008] Preferably, in step 1), the concentration of the amino-modified triphenylboroxine solution is 0.15-0.20 g / mL; The organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

[0009] Preferably, in step 1), the molar mass of the amino-modified triphenylboroxine is 15% to 20% of the molar mass of the isocyanate groups in the isocyanate-based polyurethane prepolymer.

[0010] Preferably, in step 1), the chain extension reaction conditions include: stirring the reaction at 75-85° C. for 2-4 hours.

[0011] Preferably, in step 2), the hydroxylated carbon nanotube suspension is prepared by dispersing hydroxylated carbon nanotubes in an organic solvent; the nanosilver suspension is prepared by dispersing nanosilver in an organic solvent; The concentration of the hydroxylated carbon nanotube suspension is 0.15-0.20 g / mL; the concentration of the nanosilver suspension is 0.15-0.20 g / mL; The organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

[0012] Further preferably, in step 2), the mass of the hydroxylated carbon nanotubes is 8% to 12% of the mass of the isocyanate-based polyurethane prepolymer; and the mass of the nanosilver is 8% of the total mass of the isocyanate-based polyurethane prepolymer.

[0013] Preferably, in step 2), the stirring reaction is carried out at a temperature of 75-85° C. for 3-4 hours.

[0014] Preferably, in step 2), the molding conditions include: pouring the mixed solution into a polytetrafluoroethylene plate and standing at room temperature for 24-48 hours; the drying conditions include: vacuum drying at 60-80° C. for 48-72 hours.

[0015] The present invention also discloses a polyurethane with high-efficiency electromagnetic shielding and photothermal repairability, which is prepared by adopting the above-mentioned preparation method of the polyurethane with high-efficiency electromagnetic shielding and photothermal repairability.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability. The method utilizes the reactivity of the isocyanate group, uses amino-modified triphenylboroxine and hydroxylated carbon nanotubes to extend the polyurethane chain under the action of an initiator, and simultaneously blends a certain amount of nano-silver powder to finally synthesize polyurethane with high-efficiency electromagnetic shielding and photothermal repairability. On the one hand, due to the introduction of the boron-oxygen bond, the polyurethane film can achieve self-repair under the action of water molecules. On the other hand, the introduction of hydroxylated carbon nanotubes and nano-silver gives the polyurethane film good electromagnetic shielding performance, photothermal conversion performance and antibacterial properties. The preparation route of the present invention is simple, and it is expected to solve the defect of short life of electromagnetic shielding materials, and at the same time provide new insights into the design and manufacture of multifunctional flexible wearable materials.

[0017] Furthermore, the structural formula of amino-modified triphenylboroxine was clarified to ensure that the amino group in its molecule can react with the isocyanate group; the structural stability of the dynamic reversibility of the borane bond provides a structural basis for the introduction of dynamic borate ester bonds into the polyurethane matrix, ensuring the repeatability of the self-repair function.

[0018] Furthermore, the concentration of the amino-modified triphenylboroxine solution is limited to 0.15-0.20 g / mL to avoid vigorous localized reactions caused by excessively high concentrations or inadequate chain extension caused by too low concentrations, ensuring uniform chain extension. N,N-dimethylformamide or N,N-dimethylacetamide are used to efficiently dissolve the amino-modified triphenylboroxine and are compatible with isocyanate-based polyurethane prepolymers, minimizing phase separation and ensuring stability in subsequent reactions.

[0019] Furthermore, the molar ratio of amino-modified triphenylboroxine to isocyanate group is limited to 15%~20%, which can balance the dynamic boroxine bond density and the mechanical properties of the polyurethane matrix; if the ratio is too low, the self-healing ability will be insufficient, and if the ratio is too high, the rigidity of the matrix may increase due to excessive boroxine bonds; at this ratio, sufficient dynamic bonds can be introduced to achieve repair while maintaining the flexible matrix properties of the polyurethane.

[0020] Furthermore, the chain extension reaction conditions of stirring at 75-85°C for 2-4 hours can ensure that the amino group and the isocyanate group fully react, avoid residual unreacted groups, and at the same time avoid the decomposition of the isocyanate group caused by high temperature or incomplete reaction caused by low temperature, ensuring the stability of the self-healing polyurethane prepolymer structure and providing a uniform matrix for subsequent blending.

[0021] Furthermore, the concentration of the hydroxylated carbon nanotube and nanosilver suspension is limited to 0.15-0.20 g / mL, and the use of the same solvent N,N-dimethylformamide or N,N-dimethylacetamide as in the previous study prevents nanofiller agglomeration, ensuring uniform dispersion within the polyurethane matrix and the stability of electromagnetic shielding performance. The hydroxyl groups of the hydroxylated carbon nanotubes interact with the carbamate groups in the polyurethane. When used in conjunction with the same solvent system, this further enhances the interfacial bonding between the nanofiller and the matrix, reducing performance degradation caused by filler shedding during use.

[0022] Furthermore, hydroxylated carbon nanotubes comprise 8% to 12% of the prepolymer by weight: this ratio forms a continuous conductive network, ensuring basic electromagnetic shielding effectiveness while avoiding the degradation of the matrix's mechanical properties caused by excessive addition. Nanosilver, comprising 8% of the prepolymer by weight, acts as a secondary conductive phase, synergizing with the carbon nanotubes to enhance conductivity and electromagnetic shielding while also imparting antibacterial properties. A fixed ratio ensures consistent performance. The combination of these two ratios achieves a balance between electromagnetic shielding effectiveness and matrix mechanical stability.

[0023] Furthermore, stirring the reaction at 75-85°C for 3-4 hours can ensure that the hydroxylated carbon nanotubes, nanosilver and self-healing polyurethane prepolymer fully react with each other, which not only ensures the uniform dispersion of the nanofiller, but also promotes moderate cross-linking of the matrix, avoiding internal defects of the material caused by insufficient reaction.

[0024] Furthermore, the mold is then poured after 24-48 hours of stabilization at room temperature to allow the cross-linked blend solution to slowly level and initially solidify, avoiding surface unevenness caused by rapid molding. Vacuum drying at 60-80°C for 48-72 hours completely removes the solvent, preventing residual bubbles from affecting performance while ensuring a dense material structure and stable electromagnetic shielding and self-healing properties. Mild vacuum drying conditions do not disrupt the dynamic boron-oxygen bonds or nanofiller structure, preserving the final material's performance.

[0025] This invention discloses a polyurethane with efficient electromagnetic shielding and photothermal repairability. Boron-oxygen bonds, carbon nanotubes, and silver nanoparticles are introduced into the polyurethane structure through a combination of chemical modification and physical blending. The synthesis method is simple. The dynamic reversibility of the boron-oxygen bonds and the electrical conductivity of the carbon nanotubes and silver nanoparticles are leveraged to impart the polyurethane with excellent self-healing, electromagnetic shielding, and photothermal properties, transforming traditional polyurethane materials from single-function to multifunctional. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The synthetic route of the polyurethane with high-efficiency electromagnetic shielding and photothermal repairability disclosed in the present invention is as follows; Figure 2This is the infrared absorption graph of the amino-modified triphenylboroxine, the self-healing polyurethane prepolymer, and the polyurethane with high-efficiency electromagnetic shielding and photothermal repairability in Example 2 of the present invention; Figure 3 These are two-dimensional and three-dimensional images of the polyurethane with high-efficiency electromagnetic shielding and photothermal repairability in Example 2 of the present invention before and after self-repair after being scratched, as observed using an ultra-depth-of-field microscope; Figure 4 This is a relationship diagram between the electromagnetic shielding effectiveness and the number of fracture-repair times of the polyurethane with high-efficiency electromagnetic shielding and photothermal repairability in Example 2 of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0029] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0030] In the present invention, unless otherwise specified, percentages (%) or parts refer to percentages by weight or parts by weight relative to the composition.

[0031] In the present invention, unless otherwise specified, the components involved or their preferred components can be combined with each other to form a new technical solution.

[0032] In this disclosure, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "6-22" indicates that all real numbers between "6-22" are listed herein, and "6-22" is merely an abbreviation for these numerical combinations.

[0033] The "range" disclosed in the present invention is in the form of lower limit and upper limit, which can be one or more lower limits, and one or more upper limits respectively.

[0034] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0035] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the order. Preferably, the reaction method herein is carried out sequentially.

[0036] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0037] The present invention provides a method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability, comprising the following steps: 1) A polyurethane prepolymer was subjected to a chain extension reaction using an amino-modified triphenylboroxine solution having a concentration of 0.15-0.20 g / mL. The reaction temperature was stirred at 75-85°C for 2-4 hours to obtain a self-healing polyurethane prepolymer. 2) A 0.15-0.20 g / mL hydroxylated carbon nanotube suspension and a 0.15-0.20 g / mL nanosilver suspension were added to the self-healing polyurethane prepolymer. The mixture was stirred at 75-85°C for 3-4 hours to obtain a cross-linked blend solution. The cross-linked blend solution was then molded and vacuum-dried at 60-80°C for 48-72 hours to obtain a polyurethane with high-efficiency electromagnetic shielding and photothermal repairability.

[0038] Wherein, in step 1), the structural formula of the amino-modified triphenylboroxine is: ; The solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

[0039] The amount of the amino-modified triphenylboroxine solution is calculated based on the isocyanate group content in the isocyanate-based polyurethane prepolymer; the molar mass of the amino-modified triphenylboroxine in the amino-modified triphenylboroxine solution is 15% to 20% of the molar mass of the isocyanate group in the isocyanate-based polyurethane prepolymer.

[0040] In step 2), the solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

[0041] The amount of hydroxylated carbon nanotubes in the hydroxylated carbon nanotube suspension is 8% to 12% of the mass of the isocyanate-based polyurethane prepolymer.

[0042] The mass of the nano silver is 8% of the total mass of the isocyanate-based polyurethane prepolymer.

[0043] The mold is poured into a polytetrafluoroethylene plate and left to stand at room temperature for 24 to 48 hours.

[0044] The present invention introduces dynamic boron-oxygen bonds and conductive nanofillers into polyurethane through a two-step method of chain extension of amino-modified triphenylboroxine and blending with hydroxylated carbon nanotubes and nanosilver, thereby achieving the integration of dual core functions of efficient electromagnetic shielding and photothermal repairability, breaking through the limitation of single function of traditional polyurethane. The preparation process only involves solution mixing, chain extension reaction, blending cross-linking and drying and molding, without the need for complex equipment, simple operation and easy large-scale production. Dynamic boron-oxygen bonds give the material self-repairing ability, extending its service life; hydroxylated carbon nanotubes and nanosilver synergistically improve conductivity and ensure electromagnetic shielding effectiveness; at the same time, the photothermal conversion characteristics of nanomaterials can accelerate the repair process, forming a synergistic mechanism of photothermal drive, self-repair and performance maintenance. The stability and repeatability of the material's efficient electromagnetic shielding and photothermal repairability can be guaranteed. For example, in Example 2, the scratch disappeared after 30 minutes of repair, and the electromagnetic shielding effectiveness still reached 31.75dB after three repairs. The material is also flexible (polyurethane matrix), self-healing (extended life), and antibacterial (nanosilver), and can be expanded to scenarios such as flexible wearable devices, electromagnetic shielding packaging, and electronic device protection, providing a practical basis for the design of multifunctional materials.

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0046] Example 1 A method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability comprises the following steps: 1) Preparation of self-healing polyurethane prepolymer 6.67g of isophorone diisocyanate, 10.00g of polypropylene glycol (1000 molecular weight), and 2 drops of dibutyltin dilaurate were mixed and reacted at 60°C for 2 hours. 0.68g of 1,4-butanediol was then added and the reaction continued at 70°C for 1 hour to produce an isocyanate-based polyurethane prepolymer. 1.34g of amino-modified triphenylboroxine was dissolved in 8.90mL of N,N-dimethylformamide and added dropwise to the reaction system under continuous mechanical stirring. The mixture was reacted at 75°C for 2 hours to produce a self-healing polyurethane prepolymer.

[0047] 2) Preparation of polyurethane with high-efficiency electromagnetic shielding and photothermal repairability A hydroxylated carbon nanotube suspension was prepared by dispersing 1.39 g of hydroxylated carbon nanotubes in 6.95 mL of N,N-dimethylformamide. A silver nanoparticle suspension was prepared by dispersing 1.39 g of silver nanoparticles in 6.95 mL of N,N-dimethylformamide. The hydroxylated carbon nanotube and silver nanoparticle suspensions were added to a self-healing polyurethane prepolymer and stirred at 75°C for 3 hours to produce a cross-linked blend solution. The resulting cross-linked blend solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and finally dried in a vacuum oven at 60°C for 72 hours to produce a polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability.

[0048] Example 2 A method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability comprises the following steps: 1) Preparation of self-healing polyurethane prepolymer 6.67g of isophorone diisocyanate, 10.00g of polypropylene glycol (1000 molecular weight), and 2 drops of dibutyltin dilaurate were mixed and reacted at 60°C for 2 hours. 0.68g of 1,4-butanediol was then added and the reaction continued at 70°C for 1 hour to produce an isocyanate-based polyurethane prepolymer. 1.56g of amino-modified triphenylboroxine was dissolved in 8.91mL of N,N-dimethylacetamide and added dropwise to the reaction system under continuous mechanical stirring. The mixture was reacted at 80°C for 3 hours to produce a self-healing polyurethane prepolymer.

[0049] 2) Preparation of polyurethane with high-efficiency electromagnetic shielding and photothermal repairability A hydroxylated carbon nanotube suspension was prepared by dispersing 1.74 g of hydroxylated carbon nanotubes in 9.94 mL of N,N-dimethylacetamide. A silver nanoparticle suspension was prepared by dispersing 1.39 g of silver nanoparticles in 7.94 mL of N,N-dimethylacetamide. The hydroxylated carbon nanotube and silver nanoparticle suspensions were added to a self-healing polyurethane prepolymer and stirred at 80°C for 4 hours to produce a cross-linked blend solution. The resulting cross-linked blend solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 36 hours, and finally dried in a vacuum oven at 80°C for 48 hours to produce a polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability.

[0050] See also Figure 1 This is a synthetic route for the polyurethane with high-efficiency electromagnetic shielding and photothermal repairability disclosed in the present invention; as can be seen from the figure, the entire preparation process is simple, and polyurethane with high-efficiency electromagnetic shielding and photothermal repairability can be obtained.

[0051] See also Figure 2The infrared absorption graph of amino-modified triphenylboroxine, self-repairing polyurethane prepolymer and polyurethane with high efficiency electromagnetic shielding and photothermal repairability in Example 2 of the present invention is shown in the figure. As can be seen from the figure, in the infrared spectra of the self-repairing polyurethane prepolymer and polyurethane with high efficiency electromagnetic shielding and photothermal repairability, the wavelength range of 3500-3300 cm -1 The -NH2 absorption peak originally belonging to amino-modified triphenylboroxine disappeared, and the absorption peak at 1730 cm -1 The stretching vibration peak of C=O in carbamate and the 1338 cm -1 The BO absorption peak near the urethane matrix indicates that the dynamic borate bond structure has been successfully introduced into the polyurethane matrix, indicating the successful construction of the polyurethane structure.

[0052] See also Figure 3 These are the two-dimensional and three-dimensional images of the polyurethane with high-efficiency electromagnetic shielding and photothermal repairability in Example 2 of the present invention before and after self-repair after being scratched, observed using an ultra-depth-of-field microscope; it can be seen that the polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability prepared by the present invention has good self-repairing properties. The scratches disappeared after 30 minutes of repair, and the microscopic fracture returned to a flat state.

[0053] See also Figure 4 This is a relationship diagram between the electromagnetic shielding effectiveness and the number of fractures and repairs of the polyurethane with high-efficiency electromagnetic shielding and photothermal repairability in Example 2 of the present invention; it can be seen from the figure that after three cutting-repairing cycles, the electromagnetic shielding effectiveness of the material is attenuated, but the average effectiveness is still maintained at around 31.75dB, with a decrease rate of only about 7.7%, which means that the prepared polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability has strong repair ability and structural stability.

[0054] Example 3 A method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability comprises the following steps: 1) Preparation of self-healing polyurethane prepolymer 6.67g of isophorone diisocyanate, 10.00g of polypropylene glycol (1000 molecular weight), and 2 drops of dibutyltin dilaurate were mixed and reacted at 60°C for 2 hours. 0.68g of 1,4-butanediol was then added and the reaction continued at 70°C for 1 hour to produce an isocyanate-based polyurethane prepolymer. 1.78g of amino-modified triphenylboroxine was dissolved in 11.87mL of N,N-dimethylacetamide and added dropwise to the reaction system under continuous mechanical stirring. The mixture was reacted at 85°C for 2 hours to produce a self-healing polyurethane prepolymer.

[0055] 2) Preparation of polyurethane with high-efficiency electromagnetic shielding and photothermal repairability A hydroxylated carbon nanotube suspension was prepared by dispersing 2.08 g of hydroxylated carbon nanotubes in 13.87 mL of N,N-dimethylacetamide. A silver nanoparticle suspension was prepared by dispersing 1.39 g of silver nanoparticles in 6.95 mL of N,N-dimethylacetamide. The hydroxylated carbon nanotube and silver nanoparticle suspensions were added to a self-healing polyurethane prepolymer and stirred at 85°C for 3.5 hours to produce a cross-linked blend solution. The resulting cross-linked blend solution was poured onto a polytetrafluoroethylene sheet, dried at room temperature for 48 hours, and finally dried in a vacuum oven at 70°C for 60 hours to produce a polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability.

[0056] Example 4 A method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability comprises the following steps: 1) Preparation of self-healing polyurethane prepolymer 6.67g of isophorone diisocyanate, 10.00g of polypropylene glycol (1000 molecular weight), and 2 drops of dibutyltin dilaurate were mixed and reacted at 60°C for 2 hours. 0.68g of 1,4-butanediol was then added and the reaction continued at 70°C for 1 hour to produce an isocyanate-based polyurethane prepolymer. 1.78g of amino-modified triphenylboroxine was dissolved in 10.17mL of N,N-dimethylacetamide and added dropwise to the reaction system under continuous mechanical stirring. The mixture was reacted at 80°C for 2 hours to produce a self-healing polyurethane prepolymer.

[0057] 2) Preparation of polyurethane with high-efficiency electromagnetic shielding and photothermal repairability A hydroxylated carbon nanotube suspension was prepared by dispersing 2.08 g of hydroxylated carbon nanotubes in 11.89 mL of N,N-dimethylacetamide. A silver nanoparticle suspension was prepared by dispersing 1.39 g of silver nanoparticles in 7.94 mL of N,N-dimethylacetamide. The hydroxylated carbon nanotube and silver nanoparticle suspensions were added to a self-healing polyurethane prepolymer and stirred at 80°C for 4 hours to produce a cross-linked blend solution. The resulting cross-linked blend solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 36 hours, and finally dried in a vacuum oven at 80°C for 60 hours to produce a polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability.

[0058] Example 5 A method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability comprises the following steps: 1) Preparation of self-healing polyurethane prepolymer 6.67g of isophorone diisocyanate, 10.00g of polypropylene glycol (1000 molecular weight), and 2 drops of dibutyltin dilaurate were mixed and reacted at 60°C for 2 hours. 0.68g of 1,4-butanediol was then added and the reaction continued at 70°C for 1 hour to produce an isocyanate-based polyurethane prepolymer. 1.56g of amino-modified triphenylboroxine was dissolved in 7.80mL of N,N-dimethylformamide and added dropwise to the reaction system under continuous mechanical stirring. The mixture was reacted at 75°C for 4 hours to produce a self-healing polyurethane prepolymer.

[0059] 2) Preparation of polyurethane with high-efficiency electromagnetic shielding and photothermal repairability A hydroxylated carbon nanotube suspension was prepared by dispersing 1.39 g of hydroxylated carbon nanotubes in 6.95 mL of N,N-dimethylformamide. A silver nanoparticle suspension was prepared by dispersing 1.39 g of silver nanoparticles in 6.95 mL of N,N-dimethylformamide. The hydroxylated carbon nanotube and silver nanoparticle suspensions were added to a self-healing polyurethane prepolymer and stirred at 80°C for 3 hours to produce a cross-linked blend solution. The resulting cross-linked blend solution was poured onto a polytetrafluoroethylene sheet, dried at room temperature for 48 hours, and finally dried in a vacuum oven at 75°C for 72 hours to produce a polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability.

[0060] Example 6 A method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability comprises the following steps: 1) Preparation of self-healing polyurethane prepolymer 6.67g of isophorone diisocyanate, 10.00g of polypropylene glycol (1000 molecular weight), and 2 drops of dibutyltin dilaurate were mixed and reacted at 60°C for 2 hours. 0.68g of 1,4-butanediol was then added and the reaction continued at 70°C for 1 hour to produce an isocyanate-based polyurethane prepolymer. 1.34g of amino-modified triphenylboroxine was dissolved in 8.93mL of N,N-dimethylacetamide and added dropwise to the reaction system under continuous mechanical stirring. The mixture was reacted at 80°C for 2.5 hours to produce a self-healing polyurethane prepolymer.

[0061] 2) Preparation of polyurethane with high-efficiency electromagnetic shielding and photothermal repairability A hydroxylated carbon nanotube suspension was prepared by dispersing 1.74 g of hydroxylated carbon nanotubes in 11.60 mL of N,N-dimethylformamide. A silver nanoparticle suspension was prepared by dispersing 1.39 g of silver nanoparticles in 9.27 mL of N,N-dimethylformamide. The hydroxylated carbon nanotube and silver nanoparticle suspensions were added to a self-healing polyurethane prepolymer and stirred at 75°C for 3.5 hours to produce a cross-linked blend solution. The resulting cross-linked blend solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 36 hours, and finally dried in a vacuum oven at 80°C for 48 hours to produce a polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability.

[0062] Example 7 A method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability comprises the following steps: 1) Preparation of self-healing polyurethane prepolymer 6.67g of isophorone diisocyanate, 10.00g of polypropylene glycol (1000 molecular weight), and 2 drops of dibutyltin dilaurate were mixed and reacted at 60°C for 2 hours. 0.68g of 1,4-butanediol was then added and the reaction continued at 70°C for 1 hour to produce an isocyanate-based polyurethane prepolymer. 1.78g of amino-modified triphenylboroxine was dissolved in 10.17mL of N,N-dimethylformamide and added dropwise to the reaction system under continuous mechanical stirring. The reaction was continued at 75°C for 2.5 hours to produce a self-healing polyurethane prepolymer.

[0063] 2) Preparation of polyurethane with high-efficiency electromagnetic shielding and photothermal repairability A hydroxylated carbon nanotube suspension was prepared by dispersing 1.74 g of hydroxylated carbon nanotubes in 9.94 mL of N,N-dimethylacetamide. A silver nanoparticle suspension was prepared by dispersing 1.39 g of silver nanoparticles in 7.94 mL of N,N-dimethylacetamide. The hydroxylated carbon nanotube and silver nanoparticle suspensions were added to a self-healing polyurethane prepolymer and stirred at 85°C for 3 hours to produce a cross-linked blend solution. The resulting cross-linked blend solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 48 hours, and finally dried in a vacuum oven at 65°C for 72 hours to produce a polyurethane film with high-efficiency electromagnetic shielding and photothermal repairability.

[0064] In summary, the present invention discloses a polyurethane with high-efficiency electromagnetic shielding and photothermal repairability and a preparation method. The reaction activity of the isocyanate group is utilized, and amino-modified triphenylboroxine and hydroxylated carbon nanotubes are used to extend the polyurethane chain under the action of an initiator. At the same time, a certain amount of nano-silver powder is blended to finally synthesize a polyurethane with high-efficiency electromagnetic shielding and photothermal repairability. On the one hand, due to the introduction of boron-oxygen bonds, the polyurethane film can achieve self-repair under the action of water molecules. On the other hand, the introduction of hydroxylated carbon nanotubes and nano-silver gives the polyurethane film good electromagnetic shielding performance, photothermal conversion performance and antibacterial properties. The preparation route of the present invention is simple, and it is expected to solve the defect of short life of electromagnetic shielding materials, and at the same time provide new insights into the design and manufacture of multifunctional flexible wearable materials.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability, characterized in that: The following steps are involved: 1) dissolving amino-modified triphenylboroxine in an organic solvent to obtain an amino-modified triphenylboroxine solution, and then mixing and stirring the solution with an isocyanate-based polyurethane prepolymer to perform a chain extension reaction to obtain a self-healing polyurethane prepolymer; 2) Adding a hydroxylated carbon nanotube suspension and a nanosilver suspension to a self-healing polyurethane prepolymer, stirring and reacting to obtain a cross-linked blend solution, and then sequentially casting and drying the cross-linked blend solution to obtain a polyurethane with high-efficiency electromagnetic shielding and photothermal repairability.

2. The method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability according to claim 1, characterized in that: The structural formula of the amino-modified triphenylboroxine is: 。 3. The method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability according to claim 1, characterized in that: In step 1), the concentration of the amino-modified triphenylboroxine solution is 0.15-0.20 g / mL; The organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

4. The method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability according to claim 1, characterized in that: In step 1), the molar mass of the amino-modified triphenylboroxine is 15% to 20% of the molar mass of the isocyanate group in the isocyanate-based polyurethane prepolymer.

5. The method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability according to claim 1, characterized in that: In step 1), the chain extension reaction conditions include: stirring at 75-85° C. for 2-4 hours.

6. The method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability according to claim 1, characterized in that: In step 2), the hydroxylated carbon nanotube suspension is prepared by dispersing hydroxylated carbon nanotubes in an organic solvent; the nanosilver suspension is prepared by dispersing nanosilver in an organic solvent; The concentration of the hydroxylated carbon nanotube suspension is 0.15-0.20 g / mL; the concentration of the nanosilver suspension is 0.15-0.20 g / mL; The organic solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

7. The method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability according to claim 6, characterized in that: In step 2), the mass of the hydroxylated carbon nanotubes is 8% to 12% of the mass of the isocyanate-based polyurethane prepolymer; and the mass of the nanosilver is 8% of the total mass of the isocyanate-based polyurethane prepolymer.

8. The method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability according to claim 1, characterized in that: In step 2), the stirring reaction temperature is 75-85° C. and the time is 3-4 hours.

9. The method for preparing polyurethane with high-efficiency electromagnetic shielding and photothermal repairability according to claim 1, characterized in that: In step 2), the molding conditions include: pouring the mixed solution into a polytetrafluoroethylene plate and standing at room temperature for 24 to 48 hours; the drying conditions include: vacuum drying at 60 to 80° C. for 48 to 72 hours.

10. A polyurethane with high-efficiency electromagnetic shielding and photothermal repairability, characterized in that: The polyurethane with high-efficiency electromagnetic shielding and photothermal repairability is prepared by the preparation method of any one of claims 1 to 9.

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