N-hydroxy group-containing spiro-pyran, polyionic liquid material, flexible and stretchable nanogenerator and preparation method thereof

Abstract

The present invention belongs to the technical field of new energy materials, and discloses an N-position alcohol hydroxyl group spiropyran, a polyionic liquid material, a flexible and stretchable nanogenerator and a preparation method thereof. Based on the proposed novel N-position alcohol hydroxyl group spiropyran and ionic liquid copolymerization to prepare a polyionic liquid material; the polyionic liquid material can be used to prepare a flexible and stretchable nanogenerator; the stretchability of the nanogenerator is realized, and its output electrical performance can also be effectively adjusted by adjusting the stretching rate, which can be used in fields such as intelligent flexible wearable devices and health detection, and has great application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials and relates to a polyionic liquid photoelectric conversion material, specifically to an N-position alcoholic hydroxyl spiropyran, a polyionic liquid material, a flexible and stretchable nanogenerator and a preparation method. Background Art

[0002] Currently, reported photoelectric conversion polyionic liquids incorporate azobenzene "photoisomerization units" and ionic liquid "dipole units" into the same polymer backbone. Under ultraviolet light, the azobenzene units undergo cis-trans isomerization, inducing intrinsic forces that are transmitted through the polymer chain to the ionic liquid units, causing the separation of positive and negative charge centers, thereby generating electrical signals. Traditional methods have used a coating method to assemble the synthesized photoelectric conversion polyionic liquids into nanogenerators (see Zhao J, Zhang YH, Jia YF, Bao LX, Yang LJ, Xiao SY, et al. Photomechaelectricnanogenerator. Matter. 2022;5:3977-3996). First, a polyionic liquid (PIL) is dissolved in a good solvent (e.g., DMAc) to a desired concentration (e.g., 0.05 g / mol). This solution is then spin-sprayed onto a PET transparent electrode (commonly used model: 190116-1.46) coated with a Ni-Cu alloy. The electrode is then vacuum-dried in an oven to a constant weight. A PET transparent electrode of the same material is then laminated to the other side of the material. The electrode is then pressed at 10 kN for 5 minutes at room temperature to ensure adequate contact between the PIL and the electrode. Finally, after copper wires are drawn out, the electrode is encapsulated with polydimethylsiloxane (PDMS), resulting in a nanogenerator based on a photoelectric conversion PIL.

[0003] Spiropyran, as a photoisomer unit, is an important component of photoelectric polyionic liquids. The molecular structure of spiropyran consists of an indoline ring and a benzopyran ring. In the closed ring state (SP), the two rings are in a vertical orthogonal structure; Figure 1 As shown, when irradiated with ultraviolet light, the CO bond in the spiropyran molecule undergoes heterolytic cleavage, and the two orthogonal rings are transformed into a coplanar structure, causing the SP to transform into an open ring body (MC); when the light source is removed, MC will return to the initial closed ring body SP. This transformation is inevitably accompanied by changes in the microscopic conformation within the molecule, similar to the cis-trans isomerization of azobenzene. Its structural changes can also stimulate the endogenous forces within the molecule, and further regulate the relative displacement of the positive and negative charge centers of the "dipole unit" in the same polymer system, ultimately generating an electric potential difference, thereby realizing ultraviolet photoelectric conversion.

[0004] In the prior art, phenolic hydroxyl group-containing spiropyran is used to replace azobenzene as the "photoisomerization unit", and the bisphenolic hydroxyl group in its molecular structure is used as the active site to carry out polymerization reaction to prepare a photoelectric conversion polyionic liquid material, and the dispensing method is used to replace the coating method to assemble the nanogenerator.

[0005] The above-mentioned technology still has the following deficiencies: (1) The PET transparent electrode and copper wire with Ni-Cu alloy deposited on the surface are both rigid, resulting in the assembled nanogenerator can only be bent or twisted within a very small range and does not have stretchability at all, which brings limitations to its application in the fields such as intelligent flexible wearable devices; (2) The reaction activity of phenolic hydroxyl group is relatively low, resulting in a higher polymerization reaction temperature and longer time, and it will also affect the degree of polymerization of the final product; Therefore, it is urgent to study new materials to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention aims at the problem of low reaction activity of phenolic hydroxyl group of the existing spiropyran, and provides a novel N-position alcohol hydroxyl group-containing spiropyran and a preparation method thereof, which has higher reaction activity in the preparation of polyionic liquid reaction.

[0007] Another purpose of the present invention aims to provide a polyionic liquid material and a preparation method thereof, which are prepared by using the above-mentioned N-position alcohol hydroxyl group-containing spiropyran as the raw material.

[0008] The third purpose of the present invention aims to provide a flexible and stretchable nanogenerator and a preparation method thereof, which are prepared by using the above-mentioned polyionic liquid material as the raw material. Moreover, the present invention also uses an elastic transparent TPU film and a self-made stretchable liquid metal conductive paste to replace the Ni-Cu alloy PET transparent electrode in the prior art, improves its flexibility and stretchability, and solves the problems that the existing same type of nanogenerator does not have stretchability and has a narrow application range.

[0009] According to the first aspect disclosed by the present invention, the present invention provides an N-position alcohol hydroxyl group-containing spiropyran, and its structural formula is as follows:

[0010] 。

[0011] According to the second aspect disclosed by the present invention, the present invention provides a preparation method of the above-mentioned N-position alcohol hydroxyl group-containing spiropyran, including:

[0012] Prepare 3-hydroxymethyl-5-nitrosalicylaldehyde: Dissolve 3-chloromethyl-5-nitrosalicylaldehyde in a mixed solution of acetone and deionized water, and then heat and reflux at 55-65 °C for 20-30 min; Then dropwise add an alkaline solution to the above solution at the same temperature until the pH of the solution reaches 8-10, and then heat and reflux at 75-85 °C for 6-7 h, cool to room temperature, filter, and wash to obtain 3-hydroxymethyl-5-nitrosalicylaldehyde;

[0013] Preparation of 1 - hydroxyethyl - 2,3,3 - trimethyl - 3H - indole bromide: Dissolve 2,3,3 - trimethyl - 3H - indole and 2 - bromoethanol in acetonitrile, reflux at 80 - 90 °C for 48 - 52 h, then cool to room temperature, and then rotary evaporate to obtain a dark red oily substance; Dissolve the dark red oily substance in dichloromethane, extract with deionized water, collect the aqueous phase, and then obtain 1 - hydroxyethyl - 2,3,3 - trimethyl - 3H - indole bromide through rotary evaporation and vacuum drying;

[0014] Preparation of N - hydroxy - spiro - pyran: Mix the 3 - hydroxymethyl - 5 - nitrosalicylaldehyde and 1 - hydroxyethyl - 2,3,3 - trimethyl - 3H - indole bromide, add solvent A and catalyst A, and under nitrogen protection, heat and reflux at 80 - 90 °C for 8 - 30 h, and then obtain N - hydroxy - spiro - pyran, namely 1 - hydroxyethyl 3,3 - dimethyl - 6'- nitro - 8'- hydroxymethyl - 3H - indoline spirobenzopyran through rotary evaporation and washing;

[0015] In a feasible embodiment, in the preparation of 3 - hydroxymethyl - 5 - nitrosalicylaldehyde, the alkaline solution is obtained by dissolving sodium hydroxide or potassium hydroxide in deionized water; The volume ratio of acetone to the total volume of the mixed solvent and deionized water in the alkaline solution is 2:1 - 3:1;

[0016] In the preparation of 1 - hydroxyethyl - 2,3,3 - trimethyl - 3H - indole bromide, the molar ratio of 2,3,3 - trimethyl - 3H - indole to 2 - bromoethanol is 1:1 - 1:2;

[0017] In the preparation of N - hydroxy - spiro - pyran, the molar ratio of 3 - hydroxymethyl - 5 - nitrosalicylaldehyde, 1 - hydroxyethyl - 2,3,3 - trimethyl - 3H - indole bromide, and catalyst A is 1:1:1; The solvent A is ethanol; The catalyst A is piperidine or triethylamine.

[0018] Furthermore, in the preparation of 1 - hydroxyethyl - 2,3,3 - trimethyl - 3H - indole bromide, dissolve the dark red oily substance in dichloromethane, extract with deionized water at least 3 times, collect the aqueous phase, then rotary evaporate at 75 - 85 °C to remove excess water and then vacuum dry at 80 - 90 °C to remove water to obtain 1 - hydroxyethyl - 2,3,3 - trimethyl - 3H - indole bromide;

[0019] Furthermore, in the preparation of N - hydroxy - spiro - pyran, after rotary evaporation of the black solution obtained from the heating and reflux reaction at 80 - 85 °C, obtain a dark red viscous product, and wash it three times with deionized water at 75 - 85 °C to obtain N - hydroxy - spiro - pyran.

[0020] According to the third aspect disclosed in the present invention, the present invention provides a preparation method of a poly - ionic liquid material, including:

[0021] Preparation of quaternary ammonium salt-tetrafluoroborate ionic liquid:

[0022] Respectively take polyethylene glycol and diphenylmethane diisocyanate, add catalyst B, react at 55 - 65 °C for 1 - 2 h, then raise the temperature to 75 - 85 °C and react for 1 - 2 h; then add N-hydroxyalkyl spiro pyran, react at 85 - 95 °C for 1 - 2 h; subsequently add the quaternary ammonium salt-tetrafluoroborate ionic liquid, react at 115 - 125 °C for 1 - 3 h to obtain a polyionic liquid material.

[0023] The beneficial effects of adopting the above technical solution are as follows: The present invention innovatively synthesizes N-hydroxyalkyl spiro pyran and uses it as the "photoisomerization unit" of the optoelectronic conversion polyionic liquid material. Compared with the original phenolic hydroxyl spiro pyran, the polymerization reaction activity is greatly improved, the reaction time is greatly shortened, the reaction temperature is reduced, and the reaction efficiency is improved.

[0024] In a feasible embodiment, the molar ratio of polyethylene glycol, diphenylmethane diisocyanate, N-hydroxyalkyl spiro pyran and quaternary ammonium salt-tetrafluoroborate ionic liquid is 2:4:1:1 - 2:4.1:1:1; the addition amount of catalyst B is 0.01 - 0.03% of the total mass of polyethylene glycol, diphenylmethane diisocyanate, N-hydroxyalkyl spiro pyran and quaternary ammonium salt-tetrafluoroborate ionic liquid; the catalyst B is dibutyltin dilaurate.

[0025] In a feasible embodiment, the preparation method of the quaternary ammonium salt-tetrafluoroborate ionic liquid includes:

[0026] Preparation of quaternary ammonium salt-Br ionic liquid: Stir diethanolamine and acetonitrile evenly at 55 - 65 °C, then add n-butyl bromide, reflux and stir at 85 - 95 °C for 45 - 55 h, and then obtain the quaternary ammonium salt-Br ionic liquid by rotary evaporation;

[0027] Preparation of quaternary ammonium salt-tetrafluoroborate ionic liquid: Add 1-ethyl-3-methylimidazolium tetrafluoroborate and acetonitrile to the quaternary ammonium salt-Br ionic liquid, stir and react at 25 - 30 °C for 20 - 30 h, then place it in an environment of 2 - 6 °C for 20 - 30 h, and then obtain the quaternary ammonium salt-tetrafluoroborate ionic liquid by rotary evaporation.

[0028] Furthermore, the molar ratio of diethanolamine, n-butyl bromide and 1-ethyl-3-methylimidazolium tetrafluoroborate is 1:2:1 - 1:2.1:1.

[0029] In the preparation of the quaternary ammonium salt-Br ionic liquid, for the transparent solution obtained after the reflux stirring reaction, first rotary evaporate acetonitrile at 75 - 85 °C, and then rotary evaporate the residual n-butyl bromide at 105 - 115 °C to obtain a slightly light yellow transparent viscous fluid, that is, the quaternary ammonium salt-Br ionic liquid.

[0030] In the preparation of quaternary ammonium salt-tetrafluoroborate ionic liquid, a certain amount of 1-ethyl-3-methylimidazolium tetrafluoroborate is added to the quaternary ammonium salt-Br ionic liquid, and an anion exchange reaction occurs. The purpose of refrigerating at 2-6 °C is to ensure that the anion exchange reaction occurs completely. After the refrigeration is completed, the solution is rotary evaporated at 75-85 °C to remove acetonitrile, and the quaternary ammonium salt-tetrafluoroborate ionic liquid is obtained.

[0031] In the preparation of the quaternary ammonium salt-Br ionic liquid and the quaternary ammonium salt-tetrafluoroborate ionic liquid above, acetonitrile is used as a solvent, and its amount only needs to be sufficient to ensure the progress of the reaction.

[0032] According to the fourth aspect disclosed in the present invention, the present invention provides a polyionic liquid material prepared by the above method.

[0033] According to the fifth aspect disclosed in the present invention, the present invention provides a flexible and stretchable nanogenerator prepared by the above polyionic liquid material.

[0034] The beneficial effects of adopting the above technical solution are as follows: The present invention realizes for the first time the stretchable performance of a nanogenerator based on a polyionic liquid material for photoelectric conversion. Specifically, the nanogenerator of the present invention is prepared by using a novel polyionic liquid material, which realizes stretchability, with a tensile strength of 4.61 MPa, an elongation at break of 1043.08%, and an elastic modulus of 0.78 MPa. Moreover, its output electrical performance can be effectively adjusted by adjusting the stretching rate, and it can be widely used in fields such as intelligent flexible wearable devices and health detection, with great application prospects.

[0035] In a feasible embodiment, the nanogenerator includes a five-layer structure arranged in sequence from top to bottom;

[0036] The first layer and the fifth layer are elastic transparent films; the second layer and the fourth layer are liquid metal conductive layers; the third layer is a polyionic liquid material;

[0037] The elastic transparent film is a modified thermoplastic polyurethane elastomer.

[0038] The beneficial effects of adopting the above technical solution are as follows: The present invention realizes for the first time the stretchable performance of a nanogenerator based on a polyionic liquid material for photoelectric conversion; among them, the types of "photoisomerization units" and "dipole units" of the polyionic liquid material can be replaced, such as: spiropyran derivatives, spirooxazine derivatives, azobenzene derivatives, quaternary ammonium salt ionic liquids, imidazole ionic liquids, etc.; the size (length, width, thickness) of the nanogenerator can be adjusted according to actual needs; the design of the conductive circuit can be adjusted according to needs; the elastic transparent film material can also be replaced according to needs, such as: polyurethanes, acrylic resins, etc. with different molecular structures.

[0039] In a feasible embodiment, the elastic transparent film is a modified thermoplastic polyurethane elastomer with a thickness of 100 μm. The specific parameters of the modified thermoplastic polyurethane elastomer material are as follows: Young's modulus: 10 MPa; grammage: 58 g / m 2 ; elongation at break: 1500%; elastic range: 100%; softening temperature: 120 °C; thermoforming temperature: 130 - 150 °C.

[0040] In a feasible embodiment, the liquid metal conductive paste is prepared by the following method:

[0041] Prepare 1,4 - butanediol - type polyurethane: Take polytetrahydrofuran ether glycol and hexamethylene diisocyanate, and react at 25 - 30 °C for 25 - 35 min under magnetic stirring, then raise the temperature to 55 - 65 °C and react for 25 - 35 min, and then raise the temperature to 75 - 85 °C and react for 25 - 35 min; then add 1,4 - butanediol and react at 85 - 105 °C for 2 - 4 h, and then raise the temperature to 115 - 125 °C and react for 1 - 2 h to obtain 1,4 - butanediol - type polyurethane;

[0042] Prepare Solution I: Take the 1,4 - butanediol - type polyurethane, polyethylene oxide and absolute ethanol, and stir magnetically at 75 - 85 °C until completely dissolved to obtain Solution I;

[0043] Prepare Solution II: Take liquid metal and absolute ethanol, ultrasonically disperse them evenly and then let them stand. After the solution is stable, pour out the supernatant, and reserve the lower - layer suspension to obtain Solution II; the liquid metal is a gallium - indium alloy, and the mass ratio of gallium to indium is 3:1;

[0044] Prepare the liquid metal conductive paste: Mix Solution I and Solution II evenly at 75 - 85 °C to obtain the liquid metal conductive paste.

[0045] The beneficial effects of adopting the above - mentioned technical solution are as follows: The present invention prepares a novel liquid metal paste from 1,4 - butanediol - type polyurethane, polyethylene oxide and gallium - indium alloy. The conductivity of this paste is as high as 76388.89 S, and it has excellent stretchability.

[0046] In a feasible embodiment, in the preparation of 1,4 - butanediol - type polyurethane, the molar ratio of polytetrahydrofuran ether glycol, hexamethylene diisocyanate and 1,4 - butanediol is 4:5:1 - 4:5.1:1;

[0047] In the preparation of Solution I, the mass ratio of the 1,4 - butanediol - type polyurethane to polyethylene oxide is 7:3; the solid content in Solution I is 0.05 - 0.1 g / mL;

[0048] The solid content of the liquid metal in Solution II is 0.7 - 0.9 g / mL;

[0049] In the preparation of the liquid metal conductive paste, the ratio of the total mass of 1,4-butanediol type polyurethane and polyethylene oxide in Solution I to the mass of the liquid metal in Solution II is 1:7 - 2:7.

[0050] Further, in the preparation of Solution II, the mixture of the liquid metal and absolute ethanol is placed in an ultrasonic cell disruptor and ultrasonically treated at an ultrasonic power of 100 - 110 W for 25 - 35 min, and then left to stand for 10 - 14 h. The upper clear liquid is poured out, and the lower suspension is reserved to obtain Solution II;

[0051] In the preparation of the liquid metal conductive paste, Solution I and Solution II are taken and mixed, and stirred at 75 - 85 °C using a homogenizer for 5 - 10 min, and the stirring speed is 20000 - 21000 rpm. After mixing evenly, the liquid metal conductive paste is obtained.

[0052] According to the sixth aspect disclosed by the present invention, the present invention provides a preparation method of a flexible and stretchable nanogenerator, including:

[0053] Prepare two groups of conductive line modified films I: Use a microelectronic printer to print the liquid metal conductive paste onto an elastic transparent film to obtain a group of conductive line modified films I; continue to print on another elastic transparent film to obtain another group of conductive line modified films I;

[0054] Prepare the conductive line modified film II: Add the polyionic liquid material to Solvent B for dissolution to obtain a polyionic liquid paste, and then use a microelectronic printer to print the polyionic liquid paste onto a group of conductive line modified films I to obtain the conductive line modified film II;

[0055] Prepare the flexible and stretchable nanogenerator: Bond the conductive line modified film II with another group of conductive line modified films I, and then perform plastic sealing to obtain the flexible and stretchable nanogenerator.

[0056] The beneficial effects of adopting the above technical solutions are as follows: The present invention provides a method for preparing a flexible and stretchable nanogenerator by printing conductive lines and a photo - electro - conversion polyionic liquid material onto an elastic transparent film using a microelectronic printer; using N - alcohol - hydroxyl - type spiropyran as the "photo - isomerization unit" of the photo - electro - conversion polyionic liquid material; and in the design of the conductive lines, adopting a meandering line with reciprocating bends, which can provide a good buffering effect during the stretching process and reduce the damage of the tensile force to the lines.

[0057] In a feasible implementation, in the preparation of the flexible and stretchable nanogenerator, two groups of conductive circuit modified films I are prepared. In the conductive circuit modified film I, a liquid metal conductive layer is printed by a microelectronic printer using the liquid metal conductive paste, which includes a connected support part and at least one stretching part; the support part has a planar spiral structure;

[0058] In the preparation of the conductive circuit modified film II, the polyionic liquid paste is printed onto the support part of a group of conductive circuit modified films I by a microelectronic printer to obtain the conductive circuit modified film II; the solvent B is ethanol or ethyl acetate;

[0059] In the preparation of the flexible and stretchable nanogenerator, the support part of the conductive circuit modified film II overlaps with the support part of another group of conductive circuit modified films I; the stretching parts of the conductive circuit modified film II and another group of conductive circuit modified films I face opposite directions.

[0060] Furthermore, in the conductive circuit modified film I, the stretching parts are arranged in a meandering pattern along a direction perpendicular to the support part; the stretching parts have a meandering structure with reciprocating bends.

[0061] The rotary evaporation used in the present invention is all completed under the condition of a vacuum degree of 0.06 - 0.09 MPa; the purpose of rotary evaporation is to remove unreacted raw materials, and the temperature is adjusted according to the unreacted raw materials.

[0062] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0063] (1) The present invention synthesizes N-position alcohol hydroxyl type spiropyran and uses it as the "photoisomerization unit" of the optoelectronic conversion polyionic liquid material. Compared with the original phenolic hydroxyl type spiropyran, the polymerization reaction activity is greatly improved, the reaction time can be shortened, the reaction temperature can be reduced, and the reaction efficiency is greatly improved;

[0064] (2) The present invention prepares a novel liquid metal paste from 1,4-butanediol type polyurethane, polyethylene oxide and gallium indium alloy. The conductivity of this paste is as high as 76388.89 S, which is much higher than that of the PET film with Ni-Cu alloy deposited on the surface used in the existing literature (19819.820 S), and it has excellent stretchability;

[0065] (3) The flexible and stretchable nanogenerator prepared by the present invention realizes stretchability compared with the existing optoelectronic conversion polyionic liquid nanogenerator. The tensile strength is 4.61 MPa, the elongation at break is 1043.08%, and the elastic modulus is 0.78 MPa. Moreover, its output electrical performance can be effectively adjusted by adjusting the stretching rate, and it can be used in fields such as intelligent flexible wearable devices and health detection, having great application prospects. Description of the Drawings

[0066] Figure 1 It is a schematic diagram of the ring-opening isomerization of spiropyran;

[0067] Figure 2 It is to detect the sheet resistance using an RM9010-02 type four-probe probe, where (a) is a schematic diagram of the sheet resistance of the liquid metal conductive paste prepared in Example 4 of the present invention; (b) is a schematic diagram of the PET transparent electrode with Ni-Cu alloy deposited on the surface used in the prior art;

[0068] Figure 3 It is the flexible and stretchable nanogenerator SP NOH Schematic diagram of the structure of the conductive line modified film I of IL-NG; where (a) corresponds to the physical picture, and (b) corresponds to the structure size distribution diagram of the liquid metal conductive layer;

[0069] Figure 4 It is the flexible and stretchable nanogenerator SP NOH IL-NG attached with SP NOH Schematic diagram of the structure of the conductive line modified film II of the SP NOH -IL sample; where (a) corresponds to the physical picture; (b) corresponds to the structure size distribution diagram of the SP

[0070] Figure 5 It is the flexible and stretchable nanogenerator SP NOH Physical picture (a), bending picture (b), torsion picture (c), and tensile picture after torsion (d) of IL-NG;

[0071] Figure 6 It is the flexible and stretchable nanogenerator SP NOH Schematic diagram of the stretching process of IL-NG;

[0072] Figure 7 It is the flexible and stretchable nanogenerator SP NOH Stress-strain curve graph obtained from the stretching process test of IL-NG;

[0073] Figure 8 It is the flexible and stretchable nanogenerator SP NOH Output voltage signal graph of IL-NG at different stretching rates;

[0074] Figure 9 It is the flexible and stretchable nanogenerator SP NOH Schematic diagram of the repeating unit of reciprocating bending in the stretching part of the conductive line modified film I of IL-NG. Detailed implementation manners

[0075] The principles and features of the present invention will be described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0076] Example 1

[0077] This example provides a method for preparing N-hydroxyalkyl spiropyran (SP NOH ), which includes:

[0078] Prepare 3-hydroxymethyl-5-nitrosalicylaldehyde: Dissolve 3-chloromethyl-5-nitrosalicylaldehyde (7.5 g, 0.035 mol) in a mixed solution of 40 mL of acetone and 13.5 mL of deionized water. Heat the solution under reflux at 60 °C for 20 min, then add a 6 mol / L sodium hydroxide solution (5.79 mL) dropwise at 60 °C over 35 minutes. Then heat the solution under reflux at 80 °C for 6 h, then cool it to room temperature. Filter the obtained product and wash it with deionized water to obtain a yellow-green crystal (3-hydroxymethyl-5-nitrosalicylaldehyde).

[0079]

[0080] Prepare 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide: Dissolve 2,3,3-trimethyl-3H-indole (15.923 g, 0.1 mol) and 2-bromoethanol (24.922 g, 0.2 mmol) in 300 mL of acetonitrile. React and reflux at 85 °C for 48 h, then slowly cool the mixture to room temperature and remove acetonitrile by rotary evaporation at 80 °C. Redissolve the obtained dark red oil in 100 mL of dichloromethane and extract it three times with deionized water (3 × 200 mL). Collect the aqueous phase, remove the excess water by rotary evaporation at a vacuum of 0.09 MPa and 80 °C for 2.5 h, and then dry it in a vacuum oven at 85 °C to remove water for 24 h to obtain a light red solid (1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide).

[0081]

[0082] Prepare N-hydroxyalkyl spiropyran: Weigh 3-hydroxymethyl-5-nitrosalicylaldehyde (3.943 g, 0.02 mol) and 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide (5.684 g, 0.02 mol) into a 250 mL two-necked flask, add about 150 mL of ethanol as a solvent, and then add piperidine (1.7 g, 0.02 mol). Under nitrogen, heat and reflux at 85 °C for 8 h to obtain a black solution.

[0083] The black solution was rotary evaporated at a vacuum degree of 0.09 MPa and 80 °C for 40 min to obtain a dark red viscous product, which was washed three times with deionized water at 80 °C to obtain the alcohol hydroxyl group type spiropyran unit SP. NOH (1-hydroxyethyl 3,3-dimethyl-6'-nitro-8'-hydroxymethyl-3H-indolinospiropyran).

[0084]

[0085] Example 2

[0086] Preparation method of quaternary ammonium salt-tetrafluoroborate ionic liquid "dipole unit" (IL), including:

[0087] Preparation of quaternary ammonium salt-Br ionic liquid: Weigh diethanolamine (colorless transparent viscous liquid) (10.514 g, 0.10 mol) and add it to a 500 mL single-necked flask, then add 250 mL of acetonitrile, and stir at 60 °C until there is no layering; use a syringe to measure n-butyl bromide (28.56 g, 0.21 mol), slowly inject it into the single-necked flask, and reflux and stir at 90 °C for 48 h to obtain a transparent solution. Then, first rotary evaporate the transparent solution at a vacuum degree of 0.09 MPa and 80 °C for 1 h to remove acetonitrile, and then rotary evaporate at 110 °C for 30 min to remove the residual n-butyl bromide to obtain a slightly light yellow transparent viscous fluid (quaternary ammonium salt-Br ionic liquid).

[0088] Preparation of quaternary ammonium salt-tetrafluoroborate ionic liquid: Add 1-ethyl-3-methylimidazolium tetrafluoroborate (19.8 g, 0.1 mol) to the quaternary ammonium salt-Br ionic liquid obtained in the previous step, then add 250 mL of acetonitrile, and stir at room temperature (25 - 30 °C) for 24 h to cause an anion exchange reaction to obtain a light yellow solution, and then place it in a 4 °C refrigerator for 24 h to ensure the complete occurrence of the anion exchange reaction; take out the solution from the refrigerator, rotary evaporate at a vacuum degree of 0.09 MPa and 80 °C for 1 h to remove acetonitrile to obtain the quaternary ammonium salt-tetrafluoroborate ionic liquid unit IL; in addition, 1-ethyl-3-methylimidazolium bromide is not removed and remains in the system.

[0089]

[0090] Example 3

[0091] Preparation method of polyionic liquid material (SP NOH -IL), including:

[0092] Polyethylene glycol (PEG-1000) was dehydrated under vacuum at 103 °C for 1 h, and diphenylmethane diisocyanate (MDI) was added. At the beginning of the reaction, 1 drop of catalyst dibutyltin dilaurate was added using a syringe, and the reaction was carried out at 60 °C for 1 h, then the temperature was raised to 80 °C and the reaction was carried out for 1 h, and then SP was added.NOH React at 90 °C for 1.5 h; then add IL, react at 120 °C for 2 h, and discharge; the specific material ratios are shown in Table 1:

[0093] Table 1 SP NOH Addition amounts of raw materials of -IL

[0094]

[0095] Example 4

[0096] A preparation method of a liquid metal conductive paste, comprising:

[0097] Prepare 1,4-butanediol type polyurethane: Weigh 8 g of polytetrahydrofuran ether diol (PTMG-1000) with a molecular weight of 1000 g / mol and 1.77 g of hexamethylene diisocyanate (HDI) and add them to a single-necked pressure-resistant bottle, stir magnetically, react at room temperature (25 - 30 °C) for 30 min, raise the temperature to 60 °C and react for 30 min, then raise the temperature to 80 °C and react for 30 min, then add 0.18 g of 1,4-butanediol (BDO), react at 100 °C for 3 h, and raise the temperature to 120 °C and react for 1 h to obtain 1,4-butanediol type polyurethane.

[0098] Prepare Solution I: Weigh 0.35 g of 1,4-butanediol type polyurethane, 0.15 g of polyethylene oxide (PEO), and 5 mL of absolute ethanol in a single-necked bottle, stir magnetically at 80 °C until completely dissolved to obtain Solution I.

[0099] Prepare Solution II: Weigh 3.5 g of liquid metal (gallium-indium alloy LM, mass ratio of gallium to indium is 3:1, produced by Suzhou Chuanmao Metal Materials Co., Ltd.) and place it in a sample bottle with 10 mL of absolute ethanol, and place the sample bottle in an ultrasonic cell disruptor (model: SCIENTZ-IID, produced by Ningbo Xinzhi Biotechnology Co., Ltd.) for ultrasonic treatment for 30 min with a power of 100 W, then let it stand for 12 h, pour out the upper clear liquid, and use the lower suspension as Solution II for standby.

[0100] Prepare the liquid metal conductive paste: At 80 °C, add Solution I to Solution II, and use a homogenizer (model: S10 portable high-speed homogenizer, produced by Ningbo Xinzhi Biotechnology Co., Ltd., tool diameter is 8 mm) to stir for 5 min at a rotation speed of 20000 rpm, and obtain the liquid metal conductive paste after complete mixing.

[0101] Use a wire bar to coat the above-prepared liquid metal conductive paste in a tetrafluoro mold to obtain a liquid metal film; and use an RM9010-02 type four-probe probe to measure its sheet resistance to be 0.056 Ω (as Figure 2As shown in (a); after calculation, the conductivity of the liquid metal conductive paste is 76388.899 S, and the calculation formula is as follows:

[0102]

[0103] Among them, F = D / S, where D is the probe spacing of the probe and S is the probe diameter. Both D and S are inherent parameters of the instrument. In the RM9010-02 type four-probe probe: D = 1.5 mm, S = 0.77 mm; R is the sheet resistance of the measured liquid metal film, and t is the thickness.

[0104] In addition, a PET transparent electrode (purchased externally) with a Ni-Cu alloy deposited on its surface was selected for comparison, and its sheet resistance was measured to be 0.185 Ω by the same method (as shown in Figure 2 (b)), and the conductivity was 19819.820 S, which is much lower than the liquid metal conductive paste prepared by the present invention.

[0105] Example 5

[0106] Using the polyionic liquid material SP NOH -IL to prepare a flexible and stretchable nanogenerator SP NOH IL-NG.

[0107] SP NOH The structure and composition of IL-NG:

[0108] SP NOH IL OH -NG consists of a total of 5 layers: from top to bottom, the first layer and the fifth layer (i.e., the two outermost layers) are elastic transparent films (produced by Beijing ROUZHI Technology Co., Ltd., model: Elasink-B2450); the composition of this film is modified thermoplastic polyurethane elastomer TPU (transparent, with a thickness of 100 μm); among them, the specific parameters of the modified thermoplastic polyurethane elastomer material are as follows: Young's modulus: 10 MPa; grammage: 58 g / m 2 (50 μm); elongation at break: 1500%; elastic range: 100%; softening temperature: 120 °C; hot processing temperature: 130 - 150 °C;

[0109] From top to bottom, the second layer and the fourth layer (i.e., the interlayers between the two outermost layers and the middle polymer layer) are liquid metal conductive layers; from top to bottom, the third layer (i.e., the middle polymer layer) is the synthesized SP NOH -IL material: polyionic liquid material.

[0110] The above-mentioned SP NOH The preparation method of IL-NG includes:

[0111] Prepare two groups of conductive circuit modified films Ⅰ: Use the "dispensing module" of a microelectronic printer (produced by Shanghai Mifang Electronic Technology Co., Ltd., model: MP1100) to print a self-made liquid metal conductive paste onto an Elasink-B2450 type elastic transparent film to obtain a group of conductive circuit modified films Ⅰ, and the thickness of the formed liquid metal conductive layer is about 0.08 - 0.1 mm; repeat this step on another elastic transparent film to obtain another group of conductive circuit modified films Ⅰ. Printing parameter settings: printing speed is 2 mm / s, and dispensing air pressure is 160 Kpa.

[0112] In the conductive circuit modified film Ⅰ, the liquid metal conductive layer obtained by printing the liquid metal conductive paste using a microelectronic printer includes a support part and a stretching part connected as a whole. As Figure 3 shown in Figure 3 (a) and Figure 9 (b), the support part is a planar spiral structure formed by the liquid metal paste according to the planar spiral structure trend, and the whole is square. The stretching part linearly extends from the center position of the support part in a direction perpendicular to the support part, and after extending out of the support part, it reciprocally bends according to the

[0113] repeating unit given and meanders and extends.

[0114] Among them, the support part of the conductive circuit is used for the covering and support of the polymer, and the stretching part is used for the buffering of the force during the stretching process, playing a protective role for the entire circuit.

[0114] Prepare the conductive circuit modified film Ⅱ: Dissolve the synthesized SP NOH -IL sample in ethanol or ethyl acetate (dissolve 1 g of the sample with 3 mL of the solvent), and then use the "inkjet module" of a microelectronic printer (produced by Shanghai Mifang Electronic Technology Co., Ltd., model: MP1100) to print it onto the support part of a group of prepared conductive circuit modified films Ⅰ to obtain the conductive circuit modified film Ⅱ, and the thickness of the formed polyionic liquid material is about 0.08 - 0.1 mm, as Figure 4 shown in Figure 4 )]](a) and

[0115] Prepare the flexible stretchable nanogenerator: Bond another group of conductive circuit modified films Ⅰ with the conductive circuit modified film Ⅱ, and then perform plastic sealing to obtain the flexible stretchable nanogenerator SP (a) and NOH IL-NG.

[0116] Specifically, another group of conductive circuit modification films Ⅰ and conductive circuit modification films Ⅱ are closely attached (the supporting parts overlap, and the stretching parts face left and right respectively), and are smoothly placed into a plastic sealing machine (produced by Zhejiang Daxiang Office Equipment Co., Ltd., model: 330T) for encapsulation treatment; parameter settings: the plastic sealing temperature is 80 °C, the plastic sealing speed gear is 3, and this plastic sealing process is repeated 3 times to obtain the flexible stretchable nanogenerator SP NOH IL-NG, as Figure 5 shown. From Figure 5 it can be seen that the flexible stretchable nanogenerator SP NOH IL-NG prepared by the present invention has good flexibility and stretchability.

[0117] In this experimental example, the flexible stretchable nanogenerator SP NOH IL-NG prepared in Example 5 was subjected to a tensile test, and the test process and test results are as Figure 6 and Figure 7 shown. It can be seen from the figure that the SP NOH IL-NG prepared by the present invention achieves stretchability, with a tensile strength of 4.61 MPa, an elongation at break of 1043.08%, and an elastic modulus of 0.78 MP.

[0118] This experimental example also tested the optoelectronic conversion performance at different stretching rates, and the test results are as Figure 8 and Table 2 shown. From Figure 8 and Table 2, it can be seen that the output electrical performance can be effectively adjusted by adjusting the stretching rate, and it can be used in fields such as intelligent flexible wearable devices and health detection.

[0119] Table 2 Output open circuit voltage values of SP NOH IL-NG at different stretching rates

[0120]

[0121] In summary, the present invention first uses N-position alcohol hydroxyl group type spiropyran as the "photoisomerization unit" to prepare optoelectronic conversion polyionic liquid. Compared with the original phenolic hydroxyl group type spiropyran, the polymerization reaction activity is greatly improved, the reaction time can be shortened, and the reaction temperature can be reduced, changing from "reacting at 120 °C for 3 h" to "reacting at 90 °C for 1.5 h"; the liquid metal conductive paste prepared by the present invention has good film-forming properties, a conductivity as high as 76388.899 S, and excellent stretchability; the present invention first realizes the stretchable performance of a nanogenerator based on optoelectronic conversion polyionic liquid materials, which can be widely used in fields such as intelligent flexible wearable devices and health detection, and has great application prospects.

[0122] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A preparation method of a polyionic liquid material, characterized in that Including: Preparing quaternary ammonium salt-tetrafluoroboric acid ionic liquid: Respectively take polyethylene glycol and diphenylmethane diisocyanate, add catalyst B, react at 55 - 65°C for 1 - 2 h, then raise the temperature to 75 - 85°C and react for 1 - 2 h; then add N-hydroxyalkylspiropyran, react at 85 - 95°C for 1 - 2 h; subsequently add the quaternary ammonium salt-tetrafluoroboric acid ionic liquid, react at 115 - 125°C for 1 - 3 h to obtain a polyionic liquid material; the catalyst B is dibutyltin dilaurate; The structural formula of the N-hydroxyalkylspiropyran is as follows: 。 2. The preparation method of the polyionic liquid material according to claim 1, characterized in that The preparation method of the N-hydroxyalkylspiropyran includes: Preparing 3-hydroxymethyl-5-nitrosalicylaldehyde: Dissolve 3-chloromethyl-5-nitrosalicylaldehyde in a mixed solution of acetone and deionized water, and then heat under reflux at 55 - 65°C for 20 - 30 min; then dropwise add an alkaline solution to the above solution at the same temperature until the pH of the solution reaches 8 - 10, and then heat under reflux at 75 - 85°C for 6 - 7 h, cool to room temperature, filter, and wash to obtain 3-hydroxymethyl-5-nitrosalicylaldehyde; Preparing 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide: Dissolve 2,3,3-trimethyl-3H-indole and 2-bromoethanol in acetonitrile, reflux and react at 80 - 90°C for 48 - 52 h, then cool to room temperature, and then rotary evaporate to obtain a dark red oily substance; then dissolve the dark red oily substance in dichloromethane, extract with deionized water, collect the aqueous phase, and then rotary evaporate and vacuum dry to obtain 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide; Preparing N-hydroxyalkylspiropyran: Mix the 3-hydroxymethyl-5-nitrosalicylaldehyde and 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide, then add solvent A and catalyst A, under nitrogen protection, heat under reflux at 80 - 90°C for 8 - 30 h, and then rotary evaporate and wash to obtain N-hydroxyalkylspiropyran, that is, 1-hydroxyethyl 3,3-dimethyl-6'-nitro-8'-hydroxymethyl-3H-indolinospiropyran.

3. The preparation method of the polyionic liquid material according to claim 2, characterized in that In the preparation of 3-hydroxymethyl-5-nitrosalicylaldehyde, the alkaline solution is obtained by dissolving sodium hydroxide or potassium hydroxide in deionized water; the volume ratio of acetone to the total volume of deionized water in the mixed solvent and the alkaline solution is 2:1 - 3:1; In the preparation of 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide, the molar ratio of 2,3,3-trimethyl-3H-indole to 2-bromoethanol is 1:1 - 1:2; In the preparation of N-hydroxyalkylspiropyran, the molar ratio of 3-hydroxymethyl-5-nitrosalicylaldehyde, 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide, and catalyst A is 1:1:1; the solvent A is ethanol; the catalyst A is piperidine or triethylamine.

4. The preparation method of the polyionic liquid material according to claim 1, characterized in that, The molar ratio of the polyethylene glycol, diphenylmethane diisocyanate, N-hydroxyalkyl spiro pyran, and quaternary ammonium salt-tetrafluoroborate ionic liquid is 2:4:1:1 - 2:4.1:1:1; the addition amount of the catalyst B is 0.01 - 0.03% of the total mass of the polyethylene glycol, diphenylmethane diisocyanate, N-hydroxyalkyl spiro pyran, and quaternary ammonium salt-tetrafluoroborate ionic liquid.

5. The preparation method of the polyionic liquid material according to claim 1, characterized in that, The preparation method of the quaternary ammonium salt-tetrafluoroborate ionic liquid includes: Preparing the quaternary ammonium salt-Br ionic liquid: uniformly stirring diethanolamine and acetonitrile at 55 - 65 °C, then adding n-butyl bromide, refluxing and stirring for reaction at 85 - 95 °C for 45 - 55 h, and then obtaining the quaternary ammonium salt-Br ionic liquid by rotary evaporation; Preparing the quaternary ammonium salt-tetrafluoroborate ionic liquid: adding 1-ethyl-3-methylimidazolium tetrafluoroborate and acetonitrile to the quaternary ammonium salt-Br ionic liquid, stirring and reacting at 25 - 30 °C for 20 - 30 h, then placing it in an environment of 2 - 6 °C for 20 - 30 h, and then obtaining the quaternary ammonium salt-tetrafluoroborate ionic liquid by rotary evaporation.

6. The preparation method of the polyionic liquid material according to claim 5, characterized in that: The molar ratio of the diethanolamine, n-butyl bromide, and 1-ethyl-3-methylimidazolium tetrafluoroborate is 1:2:1 - 1:2.1:

1.

7. A polyionic liquid material prepared by the method according to any one of claims 1 - 6.

8. A flexible and stretchable nanogenerator, characterized in that, Including the polyionic liquid material according to claim 7.

9. The flexible and stretchable nanogenerator according to claim 8, wherein, The nano-generator includes a five-layer structure arranged in sequence from top to bottom; The first layer and the fifth layer are elastic transparent films; the second layer and the fourth layer are liquid metal conductive layers; the third layer is a polyionic liquid material; The elastic transparent film is a modified thermoplastic polyurethane elastomer.

10. The flexible and stretchable nanogenerator according to claim 9, characterized in that it is liquid The metal conductive paste is prepared by the following method: Preparing 1,4-butanediol type polyurethane: taking polytetrahydrofuran glycol and hexamethylene diisocyanate, reacting at 25 - 30 °C for 25 - 35 min under magnetic stirring, heating to 55 - 65 °C for reaction for 25 - 35 min, and then heating to 75 - 85 °C for reaction for 25 - 35 min; then adding 1,4-butanediol, reacting at 85 - 105 °C for 2 - 4 h, and then heating to 115 - 125 °C for reaction for 1 - 2 h to obtain 1,4-butanediol type polyurethane; Preparing solution I: taking the 1,4-butanediol type polyurethane, polyethylene oxide, and absolute ethanol, stirring at 75 - 85 °C until completely dissolved to obtain solution I; Preparing solution II: taking liquid metal and absolute ethanol, ultrasonically dispersing and uniformly mixing, then standing, pouring out the upper clear liquid after the solution is stable, and using the lower suspension as standby to obtain solution II; the liquid metal is a gallium-indium alloy, and the mass ratio of gallium to indium is 3:1; Preparing the liquid metal conductive paste: mixing solution I and solution II uniformly at 75 - 85 °C to obtain the liquid metal conductive paste.

11. According to the flexible and stretchable nano-generator described in claim 10, its characteristics are In the preparation of 1,4-butanediol type polyurethane, the molar ratio of the polytetrahydrofuran glycol, hexamethylene diisocyanate, and 1,4-butanediol is 4:5:1 - 4:5.1:1; In the preparation of Solution I, the mass ratio of the 1,4-butanediol-based polyurethane to polyethylene oxide is 7:3; the solid content in Solution I is 0.05 - 0.1 g / mL; In the preparation of Solution II, the solid content of the liquid metal is 0.7 - 0.9 g / mL; In the preparation of the liquid metal conductive paste, the ratio of the total mass of the 1,4-butanediol-based polyurethane and polyethylene oxide in Solution I to the mass of the liquid metal in Solution II is 1:7 - 2:

7.

12. The preparation method of the flexible and stretchable nanogenerator according to any one of claims 9-11, characterized in that, It includes: Preparing two groups of conductive circuit modified films I: Using a microelectronic printer to print the liquid metal conductive paste onto an elastic transparent film to obtain a group of conductive circuit modified films I; Continuing to print on another elastic transparent film to obtain another group of conductive circuit modified films I; Preparing the conductive circuit modified film II: Dissolving the polyionic liquid material in Solvent B to obtain a polyionic liquid paste, and then using a microelectronic printer to print the polyionic liquid paste onto a group of conductive circuit modified films I to obtain the conductive circuit modified film II; Preparing the flexible stretchable nanogenerator: Bonding the conductive circuit modified film II with another group of conductive circuit modified films I, and then performing plastic sealing to obtain the flexible stretchable nanogenerator.

13. The preparation method of the flexible stretchable nanogenerator according to claim 12, characterized in that, Preparing two groups of conductive circuit modified films I, in the conductive circuit modified films I, the liquid metal conductive layer printed by using a microelectronic printer with the liquid metal conductive paste includes a supporting part and at least one stretching part connected as a whole; The supporting part has a planar spiral structure; In the preparation of the conductive circuit modified film II, using a microelectronic printer to print the polyionic liquid paste onto the supporting part of a group of conductive circuit modified films I to obtain the conductive circuit modified film II; the Solvent B is ethanol or ethyl acetate; In the preparation of the flexible stretchable nanogenerator, the supporting part of the conductive circuit modified film II overlaps with the supporting part of another group of conductive circuit modified films I; The stretching part of the conductive circuit modified film II and the stretching part of another group of conductive circuit modified films I face opposite directions.

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