Surface-modified self-repairing polyurethane, friction nano-generator, preparation method and application of surface-modified self-repairing polyurethane and friction nano-generator

Abstract

The invention discloses surface-modified self-repairing polyurethane, a friction nano-generator, a preparation method and application, and belongs to the technical field of material scientificity, and the preparation method of the surface-modified self-repairing polyurethane comprises the following steps: uniformly mixing a fluorine-containing group compound and hexamethylene diisocyanate, and carrying out heating reaction, extraction and drying to obtain the surface-modified self-repairing polyurethane. Mixing with serinol, dissolving in an organic solvent, heating for reaction, and drying to obtain a fluorine-containing group chain extender; and dissolving a quadruple hydrogen bond-containing chain extender and a fluorine-containing group chain extender in an organic solvent, adding the isocyanate-terminated polyurethane prepolymer, and carrying out stirring reaction, mold reversing and drying to obtain the surface-modified self-repairing polyurethane. The self-repairing polyurethane can effectively improve the environmental adaptability and the service life of the friction nanometer generator. The surface charge transfer efficiency is enhanced due to good conductivity, and the power generation performance is improved; meanwhile, the mechanical property is enhanced through hydrogen bond crosslinking, so that compared with traditional equipment, the environment universality is better.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material science, and particularly relates to a surface-modified self-repairing polyurethane and a triboelectric nanogenerator as well as a preparation method and application thereof. BACKGROUND

[0002] Due to the technical limitations of traditional generators, a triboelectric nanogenerator (TENG) emerges as the times require, which utilizes the coupling effect of triboelectricity and electrostatic induction to convert mechanical energy into electrical energy, has gradually become a breakthrough technology in the field of energy collection, can reduce resource consumption, prolong the service life of sensing devices, and meets the concept of green energy sustainable development. The TENG realizes the conversion of mechanical energy into electrical energy through the coupling of triboelectricity and electrostatic induction, but the traditional TENG has the following technical bottlenecks: 1. Insufficient mechanical properties and environmental adaptability of materials: the base material of the traditional TENG is mostly gel, which will cause problems such as water loss, poor mechanical properties, easy damage by external factors, and low adhesion with the friction layer. At the same time, due to possible damage in daily work, such as wear, scratch, fracture, etc., the performance of the TENG device inevitably decreases. 2. Complex preparation process: it needs to go through multiple steps such as emulsion polymerization and high-temperature curing, and a large amount of organic solvent is used, which has high production cost and significant energy consumption.

[0003] As a new emerging organic polymer material, polyurethane has the characteristics of high strength, high processability and high flexibility, and becomes an ideal base material for constructing TENG. However, the existing polyurethane-based TENG has the following key problems: 1. Limited surface functionalization methods: there is a lack of efficient surface charge regulation methods, and the stability of triboelectricity performance (such as surface potential and charge density) is insufficient. 2. Low energy conversion efficiency: the contact area of the planar electrode structure is limited, and the surface of most polyurethanes is relatively smooth, so the triboelectric effect is not strong. The charge capture efficiency is only 8%~10%, which is difficult to meet the continuous power supply demand of microelectronic devices.

[0004] Therefore, the application develops a polyurethane TENG with high mechanical strength and self-repairing property and a preparation method thereof, which has important significance for promoting the development of sustainable energy devices. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the purpose of the application is to provide a surface-modified self-repairing polyurethane and a triboelectric nanogenerator as well as a preparation method and application thereof, so as to solve the technical problems of poor environmental adaptability and low service life and low energy conversion efficiency of the traditional triboelectric nanogenerator.

[0006] In order to achieve the above purpose, the application adopts the following technical scheme: The application discloses a preparation method of surface-modified self-repairing polyurethane. 1) uniformly mixing fluorine-containing group compounds and hexamethylene diisocyanate, performing temperature rising reaction, extraction, drying, then mixing with serinol and dissolving in an organic solvent, performing second temperature rising reaction, and drying to obtain fluorine-containing group chain extenders; 2) dissolving the tetra-hydrogen bond-containing chain extender and the fluorine-containing group chain extender prepared in step 1) in an organic solvent, then adding an isocyanate-terminated polyurethane prepolymer, performing stirring reaction, mold pouring and drying to obtain the surface-modified self-repairing polyurethane.

[0007] Preferably, in step 1), the molar ratio of the fluorine-containing group compounds and the hexamethylene diisocyanate is 1:3; the fluorine-containing group compounds are one or more of m-ditrifluoromethyl aniline and 3,5-bistrifluoromethyl benzyl alcohol; and the extractant for extraction is n-hexane.

[0008] Preferably, in step 1), the temperature rising reaction is performed at 90-100 DEG C under the stirring speed of 150-300 r / min for 4-6 h. The second temperature rising reaction is performed at 50-70 DEG C under the stirring speed of 150-300 r / min for 4-6 h. The drying conditions are all vacuum drying at 50-70 DEG C for 8-12 h.

[0009] Preferably, in step 2), the molar ratio of the fluorine-containing group chain extender and the tetra-hydrogen bond-containing chain extender is (1-4):(4-1); and the tetra-hydrogen bond-containing chain extender is 5-(2-hydroxyethyl)-6-methyl-2-aminouracil. The stirring reaction is performed at 75 DEG C under the stirring speed of 150-300 r / min for 1-2 h, and then at 85 DEG C for 4-5 h. The mold pouring is performed at room temperature for 12-24 h; and the drying is performed at 50-80 DEG C under vacuum for 48-72 h.

[0010] Preferably, in step 2), the preparation method of the isocyanate-terminated polyurethane prepolymer is that polytetrahydrofuran, polyhexanedioic acid-1,4-butanediol ester, diisocyanate and a catalyst are mixed and reacted at 50-65 DEG C for 2-3 h to obtain the isocyanate-terminated polyurethane prepolymer. The polytetrahydrofuran is at least one of PTMEG400, PTMEG1000 and PTMEG2000; the polybutylene adipate-1,4-butylene glycol is at least one of PBA800, PBA1000 and PBA2000; the diisocyanate is isophorone diisocyanate; and the catalyst is dibutyl tin dilaurate, and the mass of the catalyst is 0.1% to 0.3% of the total mass of the polytetrahydrofuran, the polybutylene adipate-1,4-butylene glycol and the diisocyanate.

[0011] The application further discloses a surface-modified self-repairing polyurethane prepared by the preparation method.

[0012] The application further discloses a preparation method of a triboelectric nanogenerator, which comprises the following steps: sandwiching conductive modified water-based polyurethane between two layers of surface-modified self-repairing polyurethane, and obtaining a surface-modified self-repairing polyurethane positive electrode after heating and bonding; and aligning the surface-modified self-repairing polyurethane positive electrode with a polytetrafluoroethylene film negative electrode, and pasting conductive copper belts on two sides, so that the triboelectric nanogenerator is assembled. The surface-modified self-repairing polyurethane is prepared by the preparation method.

[0013] Preferably, the preparation method of the conductive modified water-based polyurethane comprises the following steps: uniformly mixing water-based polyurethane and a PEDOT:PSS water dispersion liquid according to a mass ratio of (0.5-1):(0.75-1.5), pouring a mold, and drying at room temperature to obtain the conductive modified water-based polyurethane; and the heating and bonding condition is that the drying is performed in an oven at 60-80 DEG C for 5-7 h.

[0014] The application further discloses a triboelectric nanogenerator prepared by the preparation method, wherein the triboelectric nanogenerator is in a vertical contact-separation mode; the positive electrode has a surface charge density of-45 to-35 nC / cm 2 ; the energy conversion efficiency is 15%-20%; and the voltage retention rate is greater than 95%.

[0015] The application further discloses an application of the triboelectric nanogenerator in a wearable electronic device, a self-driven sensor or a mechanical energy collection device.

[0016] Compared with the prior art, the application has the following beneficial effects: The application discloses a preparation method of surface modified self-repairing polyurethane. A fluorine-containing group compound is reacted with hexamethylene diisocyanate at a specific temperature to generate a precursor, and after unreacted monomers are removed by extraction with n-hexane, the precursor is secondarily reacted with serinol in an organic solvent to form a chain extender. The chain extender is mixed with a chain extender containing four hydrogen bonds in proportion, and then added into an isocyanate-terminated polyurethane prepolymer for chain extension reaction. During the reaction, isocyanate groups gradually polymerize with hydroxyl groups of the chain extender to form a three-dimensional crosslinked network. The fluorine-containing groups are distributed on the surface of the molecular chain to improve the surface charge density, and the four hydrogen bonds form dynamic crosslinking points between the molecular chains, so that the material can realize self-repairing through hydrogen bond recombination after being damaged. The fluorine-containing groups and the four hydrogen bond structures are integrated into the same molecular chain through chemical bonding, avoiding the problem of multiphase interface compatibility. In addition, the step-by-step reaction process simplifies the preparation process, avoids high temperature and high pressure conditions, and reduces energy consumption. The surface charge density of the polyurethane material is effectively controlled, and the dynamic self-repairing ability is also given. The introduction of the fluorine-containing groups enhances the electron transfer efficiency between the material and the friction layer, and the four hydrogen bond networks repair micro-damage through reversible rupture and recombination, thereby prolonging the service life of the device. The preparation method realizes the synergistic optimization of multiple performances through molecular structure design, and provides a reliable material basis for flexible electronic devices.

[0017] Further, in the preparation of the fluorine-containing group chain extender, the molar ratio of the fluorine-containing group compound to hexamethylene diisocyanate is controlled to be 1:3, so that the isocyanate groups are excessive, and the fluorine-containing group compound is ensured to be completely reacted to generate an intermediate product. Then, n-hexane is used as an extractant to effectively remove unreacted isocyanate monomers by taking advantage of the compatibility of n-hexane with non-polar reaction byproducts. The fluorine-containing group compound is selected to be m-ditri-fluoromethylaniline or 3,5-bistrifluoromethylbenzyl alcohol. The strong electron-withdrawing effect of the trifluoromethyl group in the molecular structure of the fluorine-containing group compound can improve the electronegativity of the polyurethane surface, and the benzene ring structure can enhance the rigidity of the chain extender. The synthesis reaction of the chain extender is efficiently carried out to ensure the purity of the intermediate product. By selecting the fluorine-containing group compound, the polyurethane surface is given stronger electronegativity. By the n-hexane extraction process, byproducts are effectively removed to improve the quality of the chain extender.

[0018] Further, in the preparation process of the fluorine-containing group chain extender, the first temperature rising reaction stage controls the stirring rate and temperature parameters to make the fluorine-containing group compound and the isocyanate monomer fully react to generate a precursor. The second temperature rising reaction stage uses a lower temperature and continuous stirring to promote the precursor and serinol to stably graft to form a stable chain extender structure. The two drying processes remove the organic solvent residues through the synergistic effect of vacuum environment and temperature, ensuring the integrity and storage stability of the chain extender molecular structure.

[0019] Further, in the preparation process, by mixing fluorine-containing group chain extender and tetra-hydrogen bond-containing chain extender in proportion, the synergistic effect of the two is utilized to construct a double-function network. The fluorine-containing group forms a low-surface-energy region through surface migration, while the tetra-hydrogen bond forms an internal self-repairing site through dynamic reversible action. During the stirring reaction at 65-85°C, the isocyanate group gradually polymerizes with the hydroxyl group of the chain extender, forming a polyurethane segment with a micro-phase separation structure. Subsequently, in the room temperature standing phase, the hydrogen bond network inside the material gradually restructures, and finally a polyurethane material with surface modification and self-repairing properties is obtained through a gradient drying process. The problems of poor surface charge stability and irreversible mechanical damage of traditional polyurethane materials are effectively solved. Through the synergistic effect of fluorine-containing groups and tetra-hydrogen bond chain extenders, the material has the ability to direct the enrichment of surface charges while maintaining high mechanical strength. The formation of a dynamic hydrogen bond network enables the material to repair itself through molecular chain segment recombination when damaged by external force, significantly improving the environmental adaptability and service life of the friction nanogenerator.

[0020] Further, the combination of polytetrahydrofuran and polyhexanedioic acid-1,4-butanediol ester can adjust the soft / hard segment ratio in the prepolymer, for example, the combination of PTMEG1000 and PBA1000 can balance the flexibility and strength of the material. The alicyclic structure of isophorone diisocyanate can effectively reduce the occurrence rate of side reactions at a reaction temperature of 50-65°C, ensuring the reactivity of the isocyanate group. The amount of catalyst is controlled at 0.1%-0.3% of the total raw material mass, for example, an addition amount of 0.2% can complete the prepolymerization within 2-3 hours, avoiding the problems of excessive reaction time due to insufficient catalyst amount or gelation caused by excessive catalyst. Through the structural characteristics of isophorone diisocyanate and the precise control of the amount of catalyst, the reaction time is shortened at a lower temperature, and the generation of by-products is reduced. The use of a single type of polyol in the prior art limits the performance adjustment of the prepolymer, while the present scheme realizes the flexible adjustment of the soft / hard segment ratio through the compounding of polyether and polyester polyols. The problems of high energy consumption and multiple side reactions caused by high-temperature reaction in the traditional prepolymer preparation process are solved, and the influence of excessive catalyst residues on the mechanical properties of the material is avoided. Through the selection and optimization of the types and ratios of polyols, the prepolymer is ensured to have a suitable molecular chain structure, providing a basis for the formation of a tetra-hydrogen bond network in the subsequent chain extension reaction, and finally making the polyurethane material have both self-repairing and surface charge regulation capabilities.

[0021] The surface modification self-repairing polyurethane disclosed by the application is prepared by mixing polytetrahydrofuran and poly-1,4-butanediol adipate in a certain proportion, adding isophorone diisocyanate and a catalyst to perform a prepolymerization reaction, then adding fluorine-containing group chain extenders and tetrahydrogen bond-containing chain extenders in stages, and realizing a chain extension process by controlling the reaction temperature and time. The fluorine-containing group chain extenders are preferentially reacted with the prepolymer to form rigid segments, and the tetrahydrogen bond-containing chain extenders are subsequently introduced to form dynamic crosslinking points. The final product forms a three-dimensional network structure after being inverted and vacuum dried, the fluorine element is enriched on the surface of the material to form electron trapping sites, and the tetrahydrogen bonds are distributed in the bulk to provide self-repairing capability. The fluorine-containing groups and tetrahydrogen bonds are introduced by step-by-step reaction to realize the synergistic construction of surface charge regulation and bulk self-repairing function at the molecular level. In the prior art, chain extenders are mostly conventional diols or amine compounds, which cannot simultaneously meet the requirements of high surface potential and damage repair, and the present application innovatively combines fluorine-containing groups and dynamic hydrogen bond networks to break through the limitation of single function. The technical defects of traditional polyurethane-based friction materials, such as low surface charge density and rapid performance degradation after damage, are effectively solved. The fluorine-containing groups form a stable electron trap layer on the surface of the material, significantly improving the triboelectric effect; the tetrahydrogen bond network can spontaneously recombine when the material is damaged, restoring the mechanical strength and electrical properties. The synergistic effect of the two makes the material maintain high energy conversion efficiency while having long-term stability.

[0022] The preparation method of the friction nanogenerator disclosed by the application can effectively solve the problems of poor environmental adaptability and short service life of traditional TENGs through the self-repairing function of the self-repairing polyurethane. By embedding a conductive layer between two layers of self-repairing polyurethane to form a sandwich structure, the heating process is used to promote the formation of hydrogen bond crosslinking between the polyurethane molecular chain and the polar groups in the conductive layer. In the positive electrode construction stage, the fluorinated surface of the surface modification self-repairing polyurethane can enhance the triboelectric effect, and the internal tetrahydrogen bond network can realize dynamic repair when mechanically damaged. The PEDOT:PSS conductive network in the conductive modification layer and the polyurethane matrix form a stable composite structure through physical entanglement, ensuring efficient charge transfer. The negative electrode uses a rough-surfaced polytetrafluoroethylene film, which has a strong electronegativity and forms a complementary triboelectric pair with the positive electrode material. During assembly, the heating temperature and time are controlled to optimize the interfacial bonding strength and avoid material degradation caused by high temperature. The structural stability and environmental adaptability of the friction nanogenerator are effectively improved. The self-repairing polyurethane layer can repair surface microcracks and maintain stable triboelectric output performance, and the close combination of the conductive modification layer and the polyurethane matrix ensures efficient charge collection and transmission. The heating bonding process simplifies the device assembly process, avoids the use of organic solvents, and enhances the interfacial strength. The device obtained by the preparation method can still maintain stable charge density and energy conversion efficiency under mechanical deformation conditions, and is suitable for wearable device application scenarios that require repeated bending.

[0023] Further, by mixing the aqueous polyurethane with the PEDOT:PSS aqueous dispersion in a specific ratio, the conductive network of PEDOT:PSS is dispersed in the polyurethane matrix to form a continuous conductive path. The inverse molding process uniformly spreads the mixed solution into a film, and room temperature drying avoids phase separation and maintains the uniformity of the conductive layer. The heating and bonding stage controls the temperature to make the polyurethane chain segments move and reorganize, form hydrogen bond cross-linking with the rubbing layer, and enhance the interfacial bonding force. This process simplifies the steps while ensuring that the conductive layer has high conductivity and mechanical strength, thereby improving the charge density and durability of the triboelectric nanogenerator.

[0024] The friction nanogenerator disclosed in the present application can significantly improve the surface charge transfer efficiency of the TENG and improve the power generation performance through the excellent conductivity of the WP film. At the same time, the hydrogen bond cross-linking between the WP film and the self-repairing polyurethane improves the mechanical properties of the self-repairing polyurethane. The friction nanogenerator uses surface-modified self-repairing polyurethane as the positive rubbing layer, and the four hydrogen bond networks and fluorine-containing groups in the self-repairing polyurethane cooperatively form stable charge capture sites. The conductive modified aqueous polyurethane is used as an intermediate conductive layer, and the uniform mixing of PEDOT:PSS and aqueous polyurethane realizes low-resistance charge transmission. The positive electrode and the polytetrafluoroethylene film negative electrode interact through the vertical contact-separation mode, and periodic contact is generated under mechanical external force, which promotes charge separation and forms a potential difference. In this process, the self-repairing property of the surface-modified polyurethane can repair the microscopic damage caused by friction and maintain the stability of the charge density, while the low-resistance property of the conductive layer reduces energy loss and improves conversion efficiency. The vertical contact-separation mode shortens the charge transfer distance, and the stable surface charge capture ability of the self-repairing polyurethane significantly improves the energy conversion efficiency.

[0025] The friction nanogenerator disclosed by the application is applied in wearable electronic devices, self-driven sensors or mechanical energy collection devices, and has excellent environmental adaptability compared with traditional TENG. The friction nanogenerator generates triboelectric charges through vertical contact separation of a surface modified self-healing polyurethane positive electrode and a polytetrafluoroethylene film negative electrode. The conductive modified waterborne polyurethane film serves as an intermediate conductive layer to realize rapid transfer of charges. When an external mechanical force acts on the device, the positive electrode and the negative electrode come into contact, and the fluorine-containing group endows the polyurethane surface with high electronegativity, so that the electrons are transferred from the polytetrafluoroethylene to the polyurethane surface. In the separation process, electrostatic induction promotes the flow of charges between the conductive layer and the electrode, forming a current output. The dynamic crosslinking network formed by the quadrimethyl hydrogen bond extender can realize self-repairing through hydrogen bond recombination after damage, and maintain the structural integrity of the friction layer. The PEDOT:PSS conductive network in the conductive modified waterborne polyurethane film is combined with the polyurethane matrix through hydrogen bond, ensuring the interface stability and avoiding the attenuation of the conductivity in the recycling process. The friction nanogenerator can provide a continuous and stable power supply for wearable electronic devices, maintain the stability of high voltage output in the human body motion energy collection scene, improve the signal detection sensitivity in the self-driven sensor application through high surface charge density, and prolong the service life of the device in complex working conditions in the mechanical energy collection device. The performance attenuation problem of traditional friction nanogenerator caused by material damage is solved, and the surface charge density and energy conversion efficiency are optimized to meet the demand of micro electronic devices for high efficiency energy collection. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A synthesis route diagram of the fluorine-containing group extender prepared for the embodiment 1 of the application; Figure 2 A synthesis route diagram of the surface modified self-healing polyurethane prepared for the embodiment 1 of the application; Figure 3 A mechanical property diagram of the surface modified self-healing polyurethane prepared for the embodiments 1-4 of the application; Figure 4 An open circuit voltage performance and short circuit current performance diagram of the friction nanogenerator prepared for the embodiments 1-4 of the application; wherein (a) is an open circuit voltage performance diagram of the friction nanogenerator, and (b) is a short circuit current performance diagram of the friction nanogenerator. DETAILED DESCRIPTION

[0027] The technical solutions of the application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0028] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0029] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0030] In the present application, percentage (%) or part refers to the percentage by weight or weight parts of the composition, if not otherwise specified.

[0031] In the present application, each component or preferred component involved can be combined to form new technical solutions, if not otherwise specified.

[0032] In the present application, unless otherwise specified, the numerical range "a~b" represents a shorthand notation for any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "1~3" represents that all the real numbers between "1~3" have been listed herein, and "1~3" is only a shorthand notation for these numerical combinations.

[0033] The lower limit and upper limit of the range disclosed in the present application can be one or more lower limits and one or more upper limits, respectively.

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

[0035] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or according to the sequence. Preferably, the reaction method herein is carried out sequentially.

[0036] Unless otherwise specified, the professional and scientific terms used herein have the same meaning 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 in the present application.

[0037] The present application discloses a preparation method of a friction nanogenerator, comprising the following steps: 1) Preparation of chain extender containing tetrahydrogen bond The guanidine carbonate and α-acetyl-γ-butyrolactone are mixed and dissolved in a solvent, and reacted under refluxing condition of triethylamine. After the reaction is completed, the product is extracted, washed, and dried to obtain the chain extender 5-(2-hydroxyethyl)-6-methyl-2-amino uracil (2-Amino-5-(2-Hydroxyethyl)-6-Methylpyrimidin-4-Alcohol, HMA) containing tetrahydrogen bond.

[0038] In step 1), the molar ratio of guanidine carbonate: alpha-acetyl-gamma-butyrolactone is (0.5-1):(1-2).

[0039] In step 1), the HMA synthesis reaction is carried out at 80-100 DEG C with stirring at a rate of 150-300 r / min for 4-6 h; the washing is carried out by alternately washing 3-5 times with deionized water and anhydrous ethanol; and the drying is carried out at 50-70 DEG C for 8-12 h.

[0040] 2) Preparation of fluorine-containing group chain extender The fluorine-containing group compound and hexamethylene diisocyanate (1,6-Diisocyanatohexane, HDI) are mixed uniformly, and after the reaction is completed at an elevated temperature, the fluorine-containing chain extender precursor is obtained by extraction and drying; then the precursor and serinol are mixed uniformly and dissolved in a solvent, and after the reaction is completed at an elevated temperature, the fluorine-containing group chain extender is obtained by drying.

[0041] In step 2), the molar ratio of the fluorine-containing group compound: HDI is 1:3.

[0042] In step 2), the precursor synthesis reaction is carried out at 90-100 DEG C with stirring at a rate of 150-300 r / min for 4-6 h; the extraction is carried out by using n-hexane as an extractant; and the drying is carried out at 50-70 DEG C under vacuum for 8-12 h.

[0043] The synthesis reaction conditions of the fluorine-containing group chain extender are as follows: stirring at a rate of 150-300 r / min at 50-70 DEG C for 4-6 h; and drying at 50-70 DEG C for 8-12 h.

[0044] In step 2), the fluorine-containing group compound is one or more of m-di(trifluoromethyl)aniline and 3,5-bistrifluoromethylbenzyl alcohol, and the solvent is N,N-dimethylformamide (DMF); and the amount of the solvent is 10 mL per 2 g of serinol.

[0045] 3) Preparation of surface-modified self-repairing polyurethane The HMA prepared in step 1) and the fluorine-containing group chain extender prepared in step 2) are dissolved in DMF to obtain a mixed solution, and then the mixed solution is added to an isocyanate-terminated polyurethane prepolymer, and after the reaction is completed with stirring, the surface-modified self-repairing polyurethane is obtained by sequentially performing reverse molding and drying.

[0046] In step 3), the molar ratio of the fluorine-containing group chain extender: HMA is (1-4):(4-1); the stirring reaction conditions are: stirring at a stirring rate of 150-300 r / min, first reacting at 75°C for 1-2 h, and then reacting at 85°C for 4-5 h. The demolding is standing at room temperature for 12-24 h; the drying conditions are: vacuum drying at 50-80°C for 48-72 h.

[0047] In step 3), the preparation method of the terminal isocyanate group polyurethane prepolymer is: mixing and reacting polytetrahydrofuran, polybutylene adipate-1,4-butylene glycol, diisocyanate and a catalyst at 50-65°C for 2-3 h to obtain a terminal isocyanate group polyurethane prepolymer; the polytetrahydrofuran is at least one of PTMEG400, PTMEG1000 and PTMEG2000; the polybutylene adipate-1,4-butylene glycol is at least one of PBA800, PBA1000 and PBA2000; the diisocyanate is isophorone diisocyanate; the catalyst is dibutyltin dilaurate, and the mass of the catalyst added is 0.1%-0.3% of the total mass of the polytetrahydrofuran, the polybutylene adipate-1,4-butylene glycol and the diisocyanate.

[0048] 4) Preparation of conductive modified waterborne polyurethane film The waterborne polyurethane (WPU) and the PEDOT:PSS aqueous dispersion (purchased from Adamas, 1.4 wt%) are mixed uniformly at a certain ratio, demolded, and dried at room temperature to obtain a conductive modified waterborne polyurethane (WP) film.

[0049] In step 4), the mass ratio of WPU:(PEDOT:PSS) is (0.5-1):(0.75-1.5).

[0050] 5) Preparation of surface modified self-healing polyurethane positive electrode The WP film prepared in step 4) is sandwiched between two layers of the surface modified self-healing polyurethane film prepared in step 3), and after heating and bonding, a surface modified self-healing polyurethane positive electrode is obtained.

[0051] In step 5), the heating and bonding conditions are: drying in an oven at 60-80°C for 5-7 h.

[0052] 6) Device assembly The surface modification self-repairing polyurethane positive electrode is aligned with a polytetrafluoroetylene (PTFE) film negative electrode with a surface roughness Ra=1~3 μm, an initial interval of 5 mm, and conductive copper bands on both sides to complete triboelectric nanogenerator (TENG) assembly, and a triboelectric nanogenerator is obtained.

[0053] In step 6), the surface modification self-repairing polyurethane triboelectric nanogenerator adopts a vertical direct contact separation mode, the surface charge density of the positive electrode is-45~-35 nC / cm 2 , and the energy conversion efficiency is 15%~20%.

[0054] The voltage retention rate of the triboelectric nanogenerator is greater than 95%.

[0055] The preparation method of the surface modification self-repairing polyurethane triboelectric nanogenerator disclosed by the application first prepares HMA and a fluorine-containing group chain extender as a small molecule chain extender, then completely dissolves the small molecule chain extender in an organic solvent, and finally adds the small molecule chain extender to a polyurethane prepolymer with terminal isocyanate groups to prepare the surface modification self-repairing polyurethane, so as to improve the crosslinking density of the polyurethane and the surface charge migration efficiency.

[0056] The WP film prepared by the above preparation method has high conductivity and hydrophilicity based on the PSS:PEDOT system, is fully mixed with WPU, and when the mass ratio of the PSS:PEDOT system to the WPU is 1.5:1, the surface resistance of the WP film reaches 10 kΩ, and the mechanical strength reaches 15 MPa.

[0057] The surface modification self-repairing polyurethane TENG prepared by the application can realize a three-dimensional crosslinking network: through the heating and bonding method in an oven, the hydrogen bonds are broken and recombined, the hydrogen bond network is formed between the four hydrogen bond groups of the friction layer and the imine groups of the conductive layer, and the mechanical strength of the material reaches 19 MPa.

[0058] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application 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 application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0059] Embodiment 1 A preparation method of a friction nanogenerator, comprising the following steps: 1) Preparation of HMA First, 5.5 g of α-acetyl-γ-butyrolactone and 3.6 g of guanidine carbonate were weighed and dissolved in 40 mL of anhydrous ethanol, then 8.1 g of triethylamine was weighed and mixed and poured into a 250 mL three-necked flask, under the condition of triethylamine reflux, the stirring rate was 150 r / min, and the reaction was carried out at 100℃ for 6 h. After the reaction was completed, the solution was cooled, and then filtered under suction to obtain a white powdery sample. The obtained sample was washed with deionized water and anhydrous ethanol for 5 times respectively, and finally dried in a vacuum drying oven at 70℃ for 12 h to obtain a white powdery HMA containing four hydrogen bonds; 2) Preparation of fluorine-containing group chain extender First, 9.2 g of m-di(trifluoromethyl) aniline and 20.2 g of HDI were uniformly mixed, and then mixed and poured into a 250 mL three-necked flask under a nitrogen atmosphere, with a stirring rate of 150 r / min, and reacted at 100℃ for 6 h. After the reaction was completed, the solution was cooled, and then extracted with n-hexane as an extractant to obtain a yellow liquid sample. The obtained sample was dried in a vacuum drying oven at 70℃ for 12 h to obtain a fluorine-containing group precursor. The fluorine-containing group precursor and serinol were uniformly mixed in DMF at a molar ratio of 1:1, and reacted at 70℃ for 6 h under a stirring rate of 150 r / min. After the reaction was completed, a yellow liquid sample was obtained, which was dried in an oven at 70℃ for 12 h to obtain a fluorine-containing group chain extender; 3) Preparation of surface-modified self-healing polyurethane Under nitrogen atmosphere, 15 mmol of isophorone diisocyanate, 1 mmol of polytetramethylene ether glycol (PTMEG1000), 4 mmol of polybutylene adipate (PBA1000) and 0.05 g of dibutyl tin dilaurate were added into a three-necked flask, the stirring rate was 150 r / min, and the temperature was raised to 65°C for 2 h to generate an isocyanate-terminated polyurethane prepolymer, then the temperature was raised to 75°C, 8 mmol of fluorine-containing group chain extender was added and reacted for 2 h to obtain an isocyanate-terminated polyurethane prepolymer, then the temperature was raised to 85°C, 2 mmol of HMA was added and reacted for 5 h to obtain a surface-modified self-repairing polyurethane solution, the obtained surface-modified self-repairing polyurethane solution was poured into a polytetrafluoroethylene plate, and was left to stand at room temperature for 24 h for drying, and finally was dried in a vacuum box at 70°C for 48 h to obtain a surface-modified self-repairing polyurethane film. 4) Preparation of WP film WPU and PSS: PEDOT water dispersion with a mass ratio of 1:1.5 were placed in a 25 mL beaker and stirred for 30 min at a stirring rate of 150 r / min and a temperature of 35°C, then the WPU / PEDOT mixed solution was poured onto a polytetrafluoroethylene plate, and was left to stand at room temperature for 12 h for drying to obtain a WP film. 5) Preparation of surface-modified self-repairing polyurethane positive electrode Two pieces of surface-modified self-repairing polyurethane film with a size of 40 mm×40 mm were cut for standby, a WP film with a size of 40 mm×40 mm was cut, and was sandwiched between the two pieces of self-repairing polyurethane film and placed in an oven for heating and bonding at 80°C for 7 h to obtain a surface-modified self-repairing polyurethane positive electrode. 6) Preparation of surface-modified self-repairing polyurethane TENG The surface-modified self-repairing polyurethane positive electrode was aligned with a PTFE film negative electrode with a surface roughness Ra=3 μm, an initial gap of 5 mm was maintained, and after the two sides were attached with copper tape composite electrodes, the surface-modified self-repairing polyurethane film was packaged to complete the preparation of a friction nanogenerator based on self-repairing polyurethane.

[0060] Example 2 A method for preparing a friction nanogenerator, comprising the following steps: 1) Preparation of HMA First, 5.5 g of α-acetyl-γ-butyrolactone and 3.6 g of guanidine carbonate were dissolved in 40 mL of anhydrous ethanol, and then 8.1 g of triethylamine was weighed and mixed into a 250 mL three-necked flask. The reaction was carried out at 95°C under reflux of triethylamine at a stirring rate of 200 r / min for 5 h. After the reaction was completed, the solution was cooled and filtered to obtain a white powder sample. The sample was washed with deionized water and anhydrous ethanol for 5 times, respectively, and finally dried in a vacuum oven at 70°C for 12 h to obtain a white powder of HMA containing four hydrogen bonds. 2) Preparation of fluorine-containing group chain extender First, 9.2 g of m-di(trifluoromethyl)aniline and 20.2 g of HDI were uniformly mixed, and then the mixture was poured into a 250 mL three-necked flask. The reaction was carried out at 100°C under nitrogen atmosphere at a stirring rate of 200 r / min for 5 h. After the reaction was completed, the solution was extracted with n-hexane to obtain a yellow liquid sample. The sample was dried in a vacuum oven at 60°C for 10 h to obtain a fluorine-containing group precursor. The fluorine-containing group precursor and serinol were uniformly mixed in DMF at a molar ratio of 1:1. The reaction was carried out at 60°C under stirring at a rate of 200 r / min for 5 h. After the reaction was completed, a yellow liquid sample was obtained. The sample was dried in an oven at 60°C for 10 h to obtain a fluorine-containing group chain extender. 3) Preparation of surface-modified self-healing polyurethane Under nitrogen atmosphere, 15 mmol of isophorone diisocyanate, 1 mmol of polytetrahydrofuran (PTMEG1000), 4 mmol of polyhexanedioic acid-1,4-butanediol ester (PBA1000), and 0.05 g of dibutyltin dilaurate were added to a three-necked flask. The reaction was carried out at a stirring rate of 200 r / min, and the temperature was raised to 50°C for 3 h, and then to 75°C for 1 h after 6 mmol of fluorine-containing group chain extender was added to obtain an isocyanate-terminated polyurethane prepolymer. Then the temperature was raised to 85°C for 4 h after 4 mmol of HMA was added to obtain a surface-modified self-healing polyurethane solution. The surface-modified self-healing polyurethane solution was poured into a polytetrafluoroethylene plate, and dried at room temperature for 20 h, and finally dried in a vacuum oven at 70°C for 56 h to obtain a surface-modified self-healing polyurethane film. 4) Preparation of WP film WPU and PSS: PEDOT aqueous dispersion with a mass ratio of 0.5:1.5 were placed in a 25 mL beaker and stirred for 30 min at a stirring rate of 150 r / min and a temperature of 35°C. Then the WPU / PEDOT mixed solution was poured onto a polytetrafluoroethylene plate, and dried at room temperature for 12 h to obtain a WP film. 5) Preparation of surface-modified self-healing polyurethane positive electrode Cut two pieces of surface modified self-healing polyurethane film with a size of 40 mm x 40 mm for standby, then cut a WP film with a size of 40 mm x 40 mm, and sandwich the WP film between the two pieces of self-healing polyurethane film and put them into an oven for heating and bonding at 80°C for 6 h to obtain a surface modified self-healing polyurethane positive electrode. 6) Preparation of surface modified self-healing polyurethane TENG Align the surface modified self-healing polyurethane positive electrode with a PTFE film negative electrode with a surface roughness Ra of 3 μm, maintain an initial gap of 5 mm, and then adhere copper tape composite electrodes on both sides. Finally, encapsulate the surface modified self-healing polyurethane film to complete the preparation of a self-healing polyurethane-based friction nanogenerator.

[0061] Example 3 A method for preparing a friction nanogenerator, comprising the following steps: 1) Preparation of HMA First, 5.5 g of α-acetyl-γ-butyrolactone and 3.6 g of guanidine carbonate were dissolved in 40 mL of anhydrous ethanol, and then 8.1 g of triethylamine was weighed and mixed into a 250 mL three-necked flask. Under the condition of triethylamine reflux, the stirring rate was 250 r / min, and the reaction was carried out at 90°C for 4 h. After the reaction was completed and the solution was cooled, the white powder sample was obtained by filtration. The sample was washed with deionized water and anhydrous ethanol 4 times, respectively, and finally dried in a vacuum drying oven at 60°C for 8 h to obtain a white powder of HMA containing four hydrogen bonds. 2) Preparation of fluorine-containing group chain extender First, 9.8 g of 3,5-bistrifluoromethylbenzyl alcohol and 20.2 g of HDI were mixed uniformly, and then the mixture was poured into a 250 mL three-necked flask. Under the condition of nitrogen atmosphere, the stirring rate was 250 r / min, and the reaction was carried out at 95°C for 4 h. After the reaction was completed and the solution was cooled, the yellow liquid sample was obtained by extraction with n-hexane as the extractant. The sample was dried in a vacuum drying oven at 60°C for 8 h to obtain a fluorine-containing group precursor. The fluorine-containing group precursor and serinol were uniformly mixed in DMF at a molar ratio of 1:1, and the reaction was carried out at 60°C for 4 h under the condition of stirring rate 250 r / min. The reaction was completed to obtain a yellow liquid sample, which was dried in an oven at 60°C for 8 h to obtain a fluorine-containing group chain extender. 3) Preparation of surface modified self-healing polyurethane Under nitrogen atmosphere, 15 mmol of isophorone diisocyanate, 1 mmol of polytetramethylene ether glycol (PTMEG2000), 4 mmol of polybutylene adipate (PBA800) and 0.04 g of dibutyl tin dilaurate were added into a three-necked flask, the stirring rate was 250 r / min, the temperature was raised to 60°C for 2.5 h, then the temperature was raised to 75°C, 4 mmol of fluorine-containing group chain extender was added and reacted for 1.5 h to obtain an isocyanate-terminated polyurethane prepolymer, then the temperature was raised to 85°C, 6 mmol of HMA was added and reacted for 4 h to obtain a surface-modified self-healing polyurethane solution, the obtained surface-modified self-healing polyurethane solution was poured into a polytetrafluoroethylene plate, and was left to dry at room temperature for 16 h, and finally was dried in a vacuum box at 70°C for 64 h to obtain a surface-modified self-healing polyurethane film. 4) Preparation of WP film WPU and PSS: PEDOT aqueous dispersion with a mass ratio of 1:1 were placed in a 25 mL beaker and stirred for 30 min at a stirring rate of 150 r / min and a temperature of 35°C, then the WPU / PEDOT mixed solution was poured onto a polytetrafluoroethylene plate and dried at room temperature for 12 h to obtain a WP film. 5) Preparation of surface-modified self-healing polyurethane positive electrode Two pieces of surface-modified self-healing polyurethane film with a size of 40 mm x 40 mm were cut for standby, and a WP film with a size of 40 mm x 40 mm was cut and sandwiched between the two pieces of self-healing polyurethane film and placed in an oven, and heated at 70°C for 5 h to obtain a surface-modified self-healing polyurethane positive electrode. 6) Preparation of surface-modified self-healing polyurethane TENG The surface-modified self-healing polyurethane positive electrode was aligned with a PTFE film negative electrode with a surface roughness Ra of 2 μm, and an initial spacing of 5 mm was maintained, then copper tape composite electrodes were attached to both sides, and the surface-modified self-healing polyurethane film was used for packaging to complete the preparation of a self-healing polyurethane-based triboelectric nanogenerator.

[0062] Example 4 A method for preparing a triboelectric nanogenerator, comprising the following steps: 1) Preparation of HMA First, 5.5 g of a-acetyl-g-butyrolactone and 3.6 g of guanidine carbonate were dissolved in 40 mL of anhydrous ethanol, and then 8.1 g of triethylamine was weighed and mixed into a 250 mL three-necked flask. The reaction was carried out at 80°C under refluxing condition of triethylamine with a stirring rate of 300 r / min for 5 h. After the reaction was completed, the solution was cooled and filtered to obtain a white powder sample. The sample was washed with deionized water and anhydrous ethanol for 3 times, respectively, and finally dried in a vacuum oven at 50°C for 10 h to obtain a white powder of HMA containing tetrahydrogen bond. 2) Preparation of fluorine-containing group chain extender First, 4.9 g of 3,5-bistrifluoromethyl benzyl alcohol, 4.6 g of m-di(trifluoromethyl) aniline and 20.2 g of HDI were mixed uniformly, and then the mixture was poured into a 250 mL three-necked flask. The reaction was carried out at 90°C under nitrogen atmosphere with a stirring rate of 300 r / min for 5 h. After the reaction was completed, the solution was extracted with n-hexane to obtain a yellow liquid sample. The sample was dried in a vacuum oven at 50°C for 10 h to obtain a fluorine-containing group precursor. The fluorine-containing group precursor and serinol were uniformly mixed in DMF at a molar ratio of 1:1. The reaction was carried out at 50°C with a stirring rate of 300 r / min for 5 h. After the reaction was completed, a yellow liquid sample was obtained. The sample was dried in an oven at 50°C for 10 h to obtain a fluorine-containing group chain extender. 3) Preparation of surface-modified self-healing polyurethane Under nitrogen atmosphere, 15 mmol of isophorone diisocyanate, 1 mmol of polytetrahydrofuran (PTMEG400), 4 mmol of polyhexanedioic acid-1,4-butanediol ester (PBA2000) and 0.03 g of dibutyl tin dilaurate were added into a three-necked flask with a stirring rate of 300 r / min. The temperature was raised to 55°C for 2.5 h, and then the temperature was raised to 75°C for adding 2 mmol of fluorine-containing group chain extender for 1 h to obtain an isocyanate-terminated polyurethane prepolymer. Then the temperature was raised to 85°C for adding 8 mmol of HMA for 4.5 h to obtain a surface-modified self-healing polyurethane solution. The surface-modified self-healing polyurethane solution was poured into a polytetrafluoroethylene plate, and then dried at room temperature for 12 h. Finally, the surface-modified self-healing polyurethane film was dried in a vacuum oven at 50°C for 72 h. 4) Preparation of WP film WPU and PSS:PEDOT water dispersion with a mass ratio of 1:0.75 were placed in a 25 mL beaker and stirred for 30 min at a stirring rate of 150 r / min and a temperature of 35°C. Then the WPU / PEDOT mixed solution was poured onto a polytetrafluoroethylene plate, and then dried at room temperature for 12 h to obtain a WP film. 5) Preparation of surface modified self-healing polyurethane positive electrode Two pieces of surface modified self-healing polyurethane film with a size of 40 mm x 40 mm were cut for standby, and a WP film with a size of 40 mm x 40 mm was cut, which was sandwiched between the two pieces of self-healing polyurethane film and placed in an oven, heated and bonded in an oven at 60°C for 6 h to obtain a surface modified self-healing polyurethane positive electrode; 6) Preparation of surface modified self-healing polyurethane TENG The surface modified self-healing polyurethane positive electrode was aligned with a PTFE film negative electrode with a surface roughness Ra = 1 μm, an initial gap of 5 mm was maintained, and after the copper belt composite electrode was attached on both sides, the surface modified self-healing polyurethane film was packaged to complete the preparation of the self-healing polyurethane-based friction nanogenerator.

[0063] The open-circuit voltage, short-circuit current and stability of the self-healing polyurethane friction nanogenerator prepared in Examples 1-4 were tested, and the test time was 60 s. The test results were the average of 5 sets of data, and the results are shown in Table 1.

[0064] Table 1 Electrical performance test results of the friction nanogenerator prepared in Examples 1-4

[0065] Table 1 is the electrical performance test results of the friction nanogenerator prepared in Examples 1-4; the experimental data in the table show that the present application significantly improves the charge density and charge transfer efficiency of the TENG through the design of a quadruple hydrogen bond crosslinking network structure, and according to Figure 3 The TENG has good voltage, stable current and excellent stability, and the TENG has the highest output voltage when the surface modified self-healing polyurethane is synthesized under the condition of using 1 mmol PTMEG, 4 mmol PBA, 2 mmol HMA and 8 mmol fluorine-containing group chain extender.

[0066] Referring to Figure 1 is the synthesis route of the fluorine-containing group chain extender in Example 1 of the present application; as can be seen from the figure, by the first step reaction, the group containing double trifluoromethyl is connected to the long chain on one end of HDI by the reaction of isocyanate group and amino group, and then by the second step reaction, the fluorine-containing group chain extender for polyurethane chain extension reaction is obtained by the reaction of isocyanate group on the other end of HDI and the amino group of serinol.

[0067] Figure 2The synthesis route of the surface modified self-repairing polyurethane prepared in Example 1 of the present application is shown in the figure; as can be seen from the figure, first, isophorone diisocyanate, polytetramethylene glycol (PTMEG1000) and polybutylene adipate (PBA1000) are subjected to prepolymerization under the catalysis of a catalyst dibutyltin dilaurate to obtain a double-end isocyanate group polyurethane prepolymer, then HMA and a fluorine-containing group chain extender are subjected to polyurethane chain extension to increase the overall molecular weight of the polyurethane material, and further to improve the mechanical properties and surface electron-withdrawing properties of the polyurethane material, and finally after the isocyanate group is completely consumed, the surface modified self-repairing polyurethane is obtained. The polyurethane material prepared by this process not only has excellent mechanical properties, but also has good self-repairing properties and surface charge transfer efficiency.

[0068] Figure 3 The mechanical property figure of the surface modified self-repairing polyurethane prepared in Examples 1-4 of the present application is shown in the figure; as can be seen from the figure, the surface modified self-repairing polyurethane prepared in Example 1 has the highest tensile strength, reaching 19 MPa, measured by a tensile testing machine clamping an I-shaped standard sample, and the samples prepared in Examples 2-4 gradually decrease, and the sample prepared in Example 4 has the lowest tensile strength, only 2 Mpa, indicating that as the amount of the fluorine-containing group chain extender decreases, the degree of hydrogen bond crosslinking between the polyurethane chains decreases, and the tensile strength of the sample decreases. From the perspective of elongation, the sample prepared in Example 4 has the highest elongation, and the samples prepared in Examples 3-1 gradually decrease in elongation, but the sample prepared in Example 1 has higher tensile rate than the sample prepared in Example 2, which has good tensile rate while meeting high tensile strength, and in summary, the sample prepared in Example 1 has the best mechanical properties.

[0069] Figure 4 The open-circuit voltage performance and short-circuit current performance figures of the friction nanogenerator prepared in Examples 1-4 of the present application are shown in the figure; wherein (a) is the open-circuit voltage performance figure of the friction nanogenerator, and (b) is the short-circuit current performance figure of the friction nanogenerator; as can be seen from the figure, the open-circuit voltage of the sample prepared in Example 1 reaches 40 V, and the short-circuit current reaches 90 nA, measured by a oscilloscope linked to the friction nanogenerator, and the power generation performance of the samples prepared in Examples 2-4 gradually decreases, indicating that as the amount of the fluorine-containing group chain extender decreases, the electronegativity of the surface of the prepared sample decreases, the charge transfer efficiency decreases, and further leads to the decrease of the power generation capacity.

[0070] In summary, the surface modified self-repairing polyurethane and the triboelectric nanogenerator and the preparation method and the application, first, a small molecule chain extender HMA containing four hydrogen bonds is prepared, and a fluorine-containing group chain extender is prepared, then the two chain extenders are added to the isocyanate-terminated polyurethane prepolymer to prepare a series of surface modified self-repairing polyurethane for standby. Then the WPU and the PEDOT: PSS aqueous dispersion are mixed in a certain proportion to prepare a conductive film for standby. Finally, the self-repairing polyurethane is used as a friction layer, and the conductive film is used as a conductive layer to construct a positive friction electrode, and the PTFE film is used as a friction layer, and the copper strip is used as a conductive layer to construct a negative friction electrode, and the surface modified self-repairing polyurethane TENG is constructed based on the combination of the two electrodes. The preparation route of the application is simple, which reduces the complexity of the system in design and processing, based on the strong designability of the polyurethane molecular structure and the flexible controllability of the soft and hard segments, the TENG can have excellent mechanical strength and good triboelectric performance at the same time, and the service life of the TENG is improved by using the repairability of the self-repairing polyurethane and the excellent mechanical performance. Through the synergistic innovation of the fluorine-containing group chain extender and the WP film, the triboelectric performance and the service life are improved. The technology process is simple, the device has high energy conversion capacity and good cycle stability, which provides a sustainable energy solution for wearable flexible electronics, intelligent sensing, energy collection and other fields, and has significant scientific value and application prospect.

[0071] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a surface-modified self-healing polyurethane, characterized by, The method comprises the following steps: 1) uniformly mixing fluorine-containing group compound and hexamethylene diisocyanate, and then performing temperature rising reaction, extraction, drying, mixing with serinol in an organic solvent, and performing second temperature rising reaction and drying to obtain fluorine-containing group chain extender; 2) dissolving the chain extender containing tetrahydrogen bond and the fluorine-containing group chain extender prepared in step 1) in an organic solvent, adding terminal isocyanate group polyurethane prepolymer, and then performing stirring reaction, mold pouring and drying to obtain surface modified self-repairing polyurethane.

2. The method for preparing a surface-modified self-repairing polyurethane according to claim 1, characterized in that, In step 1), the molar ratio of the fluorine-containing group compound to hexamethylene diisocyanate is 1:3; the fluorine-containing group compound is one or more of m-ditri-fluoromethylaniline and 3,5-bistrifluoromethyl benzyl alcohol; and the extraction agent for the extraction is n-hexane.

3. The preparation method of the surface-modified self-healing polyurethane according to claim 1, characterized in that, In step 1), the temperature rising reaction is performed at 90-100 DEG C under stirring at a stirring speed of 150-300 r / min for 4-6 h. The second temperature rising reaction is performed at 50-70 DEG C under stirring at a stirring speed of 150-300 r / min for 4-6 h. The drying is performed at 50-70 DEG C under vacuum for 8-12 h.

4. The preparation method of the surface-modified self-healing polyurethane according to claim 1, characterized in that, In step 2), the molar ratio of the fluorine-containing group chain extender to the chain extender containing tetrahydrogen bond is (1-4):(4-1); the chain extender containing tetrahydrogen bond is 5-(2-hydroxyethyl)-6-methyl-2-aminouracil; The stirring reaction is performed at 75 DEG C under stirring at a stirring speed of 150-300 r / min for 1-2 h, and then the temperature is raised to 85 DEG C for continuous reaction for 4-5 h; The mold pouring is performed at room temperature for 12-24 h; and the drying is performed at 50-80 DEG C under vacuum for 48-72 h.

5. The method for preparing surface-modified self-healing polyurethane according to claim 1, characterized in that, In step 2), the terminal isocyanate group polyurethane prepolymer is prepared by mixing polytetrahydrofuran, polybutylene adipate, diisocyanate and catalyst at 50-65 DEG C for 2-3 h. The polytetrahydrofuran is at least one of PTMEG400, PTMEG1000 and PTMEG2000; the polybutylene adipate is at least one of PBA800, PBA1000 and PBA2000; the diisocyanate is isophorone diisocyanate; and the catalyst is dibutyltin dilaurate, and the mass of the catalyst is 0.1%-0.3% of the total mass of the polytetrahydrofuran, polybutylene adipate and diisocyanate.

6. A surface-modified self-healing polyurethane, characterized by The surface modified self-repairing polyurethane is prepared by the method in any one of claims 1-5.

7. A method for preparing a friction nanogenerator, characterized in that, The method comprises the following steps: The conductive modified waterborne polyurethane is sandwiched between two layers of surface modified self-repairing polyurethane, and then the surface modified self-repairing polyurethane is heated and bonded to obtain surface modified self-repairing polyurethane positive electrode; the surface modified self-repairing polyurethane positive electrode and a polytetrafluoroethylene film negative electrode are aligned, and conductive copper belts are attached to the two sides, and then the rubbing nanogenerator is assembled. The surface-modified self-repairing polyurethane is prepared by the method of any one of claims 1-5.

8. The method for preparing the triboelectric nanogenerator according to claim 7, characterized in that, The preparation method of the conductive modified waterborne polyurethane comprises: uniformly mixing waterborne polyurethane and a PEDOT:PSS water dispersion liquid according to a mass ratio of (0.5-1):(0.75-1.5), pouring a mold, and drying at room temperature to obtain the conductive modified waterborne polyurethane; the heating and bonding condition is: drying in an oven at 60-80 DEG C for 5-7 h.

9. A friction nanogenerator, characterized in that, The friction nanogenerator is prepared by the preparation method of claim 7 or 8, and has the following characteristics: the friction nanogenerator is in a vertical contact separation mode; the surface charge density of the positive electrode is -45~ -35 nC / cm 2 ; the energy conversion efficiency is 15%~20%; and the voltage retention rate is greater than 95%.

10. Use of the friction nanogenerator of claim 9 in a wearable electronic device, a self-powered sensor, or a mechanical energy harvesting device.

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