N-site alcoholic hydroxyl spiropyrane, polyion liquid material, flexible stretchable nano-generator and preparation method

Abstract

The invention belongs to the technical field of new energy materials, and discloses an N-site alcoholic hydroxyl spiropyrane, a polyionic liquid material, a flexible stretchable nano-generator and a preparation method, and the polyionic liquid material is prepared based on copolymerization of the provided novel N-site alcoholic hydroxyl spiropyrane and ionic liquid; the polyion liquid material can be used for preparing a flexible and stretchable nano generator; the stretchability of the nano-generator is realized, the output electrical performance of the nano-generator can be effectively adjusted by adjusting the stretch rate, and the nano-generator can be applied to the fields of intelligent flexible wearable equipment, health detection and the like and has a huge application prospect.

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, and specifically to an N-position alcohol hydroxyl spiropyran, a polyionic liquid material, a flexible and stretchable nanogenerator, and a preparation method thereof. Background Art

[0002] At present, the photoelectric conversion polyionic liquid materials reported in the prior art introduce azobenzene "photoisomerization unit" and ionic liquid "dipole unit" into the same polymer main chain; under ultraviolet light irradiation, the azobenzene unit undergoes cis-trans isomerization, inducing endogenous forces, which are transmitted to the ionic liquid unit through the polymer chain, causing the positive and negative charge centers to separate, thereby generating electrical signals. Traditional methods all use a coating method to assemble the synthesized photoelectric conversion polyionic liquid into a nanogenerator (see Zhao J, Zhang YH, Jia YF, Bao LX, Yang LJ, Xiao SY, et al. Photomechaelectricnanogenerator. Matter. 2022;5:3977-3996). First, the polyionic liquid is dissolved in a good solvent (such as DMAc) to prepare a polymer solution of a certain concentration (such as 0.05g / mol); then, the solution is sprayed on a PET transparent electrode (commonly used model: 190116-1.46) with Ni-Cu alloy deposited on the surface, and placed in an oven for vacuum drying to constant weight; then, a layer of PET transparent electrode of the same material is attached to the other side of the material, and pressed at a pressure of 10 kN for 5 minutes at room temperature to ensure sufficient contact between the polyionic liquid and the electrode. Finally, after the copper wire is drawn out, polydimethylsiloxane (PDMS) is used for encapsulation to obtain a nanogenerator based on photoelectric conversion polyionic liquid.

[0003] Spiropyran, as a photoisomer unit, is an important component of photoelectric polyionic liquids. The molecular structure of spiropyran is composed 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, resulting in the transformation of SP 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 inside 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 a potential difference, thereby realizing ultraviolet photoelectric conversion.

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

[0005] The above technology still has the following shortcomings: (1) The PET transparent electrode and copper wire with Ni-Cu alloy deposited on the surface are both hard, resulting in the assembled nanogenerator being able to bend or twist only within a very small range and having no stretchability at all, which limits its application in the fields of smart flexible wearable devices; (2) The phenolic hydroxyl group has low reactivity, resulting in a high polymerization temperature and a long time, which also affects 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 is to provide a novel N-position alcohol hydroxyl spiropyran and a preparation method thereof to solve the problem of low reactivity of existing spiropyran phenol hydroxyl groups, which has higher reactivity in the preparation of polyionic liquids.

[0007] Another object of the present invention is to provide a polyionic liquid material and a preparation method thereof, which is prepared using the above-mentioned N-hydroxyl alcohol spiropyran as a raw material.

[0008] The third object of the present invention is to provide a flexible and stretchable nanogenerator and a preparation method, which is prepared using the above-mentioned polyionic liquid material as a raw material. In addition, the present invention also replaces the Ni-Cu alloy PET transparent electrode in the prior art with an elastic transparent TPU film and a self-made stretchable liquid metal conductive slurry to improve its flexibility and stretchability, thereby solving the problem that the existing nanogenerators of the same type do not have stretchability and have a narrow application range.

[0009] According to the first aspect of the present disclosure, the present invention provides an N-hydroxyl alcohol spiropyran, the structural formula of which is shown below: .

[0010] According to the second aspect of the present disclosure, the present invention provides a method for preparing the above-mentioned N-alcoholic hydroxy spiropyran, comprising: Preparation of 3-hydroxymethyl-5-nitrosalicylicaldehyde: dissolving 3-chloromethyl-5-nitrosalicylicaldehyde in a mixed solution of acetone and deionized water, and then heating and reflux at 55-65° C. for 20-30 minutes; then adding alkaline solution dropwise to the above solution at the same temperature until the pH value of the solution reaches 8-10, and then heating and reflux at 75-85° C. for 6-7 hours, cooling to room temperature, filtering, and washing to obtain 3-hydroxymethyl-5-nitrosalicylicaldehyde; Preparation of 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide: dissolving 2,3,3-trimethyl-3H-indole and 2-bromoethanol in acetonitrile, reflux reaction at 80-90° C. for 48-52 hours, cooling to room temperature, and then rotary evaporation to obtain a dark red oil; then dissolving the dark red oil in dichloromethane, extracting with deionized water, collecting the aqueous phase, and then rotary evaporation and vacuum drying to obtain 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide; Preparation of N-alcoholic hydroxy spiropyran: 3-hydroxymethyl-5-nitrosalicylicylaldehyde and 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide are mixed, solvent A and catalyst A are added, and the mixture is heated to reflux at 80-90° C. for 8-30 hours under nitrogen protection, and then subjected to rotary evaporation and washing to obtain N-alcoholic hydroxy spiropyran, i.e., 1-hydroxyethyl 3,3-dimethyl-6'-nitro-8'-hydroxymethyl-3H-indoline spirobenzopyran.

[0011] In one feasible embodiment, the preparation of 3-hydroxymethyl-5-nitrosalicylic aldehyde, the alkaline solution is obtained by dissolving sodium hydroxide or potassium hydroxide in deionized water; the volume ratio of acetone to the total amount 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-alcoholic hydroxy spiropyran, the molar ratio of the 3-hydroxymethyl-5-nitrosalicylicylaldehyde, 1-hydroxyethyl-2,3,3-trimethyl-3H-bromoindole and the catalyst A is 1:1:1; the solvent A is ethanol; and the catalyst A is piperidine or triethylamine.

[0012] Further, in the preparation of 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide, the dark red oil is dissolved in dichloromethane, extracted with deionized water at least 3 times, the aqueous phase is collected, and then the excess water is removed by rotary evaporation at 75-85° C. and then vacuum dried at 80-90° C. to obtain 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide; Furthermore, in the preparation of N-hydroxy alcohol spiropyran, the black solution obtained by heating reflux reaction is rotary evaporated at 80-85° C. to obtain a dark red viscous product, and the product is washed three times in deionized water at 75-85° C. to obtain N-hydroxy alcohol spiropyran.

[0013] According to a third aspect of the present disclosure, the present invention provides a method for preparing a polyionic liquid material, comprising: Preparation of quaternary ammonium salt-tetrafluoroborate ionic liquid: Take polypropylene glycol and diphenylmethane diisocyanate respectively, add catalyst B, react at 55-65°C for 1-2h, then heat to 75-85°C for 1-2h; then add N-position alcohol hydroxy spiropyran, react at 85-95°C for 1-2h; then add the quaternary ammonium salt-tetrafluoroborate ionic liquid, react at 115-125°C for 1-3h to obtain a polyionic liquid material.

[0014] The beneficial effects of adopting the above technical scheme are as follows: the present invention innovatively synthesizes N-position alcoholic hydroxyl type spiropyran and uses it as the "photoisomerization unit" of the photoelectric conversion polyionic liquid material. Compared with the original phenolic hydroxyl type spiropyran, the polymerization reaction activity is greatly improved, the reaction time is greatly shortened, the reaction temperature is reduced, and the reaction efficiency is improved.

[0015] In a feasible embodiment, the molar ratio of the polypropylene glycol, diphenylmethane diisocyanate, N-position alcohol hydroxyl spiropyran and quaternary ammonium salt-tetrafluoroborate ionic liquid is 2:4:1:1-2:4.1:1:1; the added amount of the catalyst B is 0.01-0.03% of the total mass of the polypropylene glycol, diphenylmethane diisocyanate, N-position alcohol hydroxyl spiropyran and quaternary ammonium salt-tetrafluoroborate ionic liquid; and the catalyst B is dibutyltin dilaurate.

[0016] In a feasible embodiment, the preparation method of the quaternary ammonium salt-tetrafluoroborate ionic liquid comprises: Preparation of quaternary ammonium salt-Br ionic liquid: diethanolamine and acetonitrile are stirred evenly at 55-65° C., then n-butyl bromide is added, and the mixture is refluxed and stirred at 85-95° C. for 45-55 hours, and then the quaternary ammonium salt-Br ionic liquid is obtained by rotary evaporation; 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 hours, then place at 2-6° C. for 20-30 hours, and then rotary evaporate to obtain the quaternary ammonium salt-tetrafluoroborate ionic liquid.

[0017] Furthermore, the molar ratio of diethanolamine, n-butyl bromide and 1-ethyl-3-methylimidazolium tetrafluoroborate is 1:2:1-1:2.1:1.

[0018] In the preparation of the quaternary ammonium salt-Br ionic liquid, the transparent solution obtained after the reflux stirring reaction is firstly subjected to rotary evaporation at 75-85°C to remove acetonitrile, and then the residual n-butyl bromide is removed by rotary evaporation at 105-115°C to obtain a slightly light yellow transparent viscous fluid, i.e., the quaternary ammonium salt-Br ionic liquid.

[0019] In the preparation of the 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 to cause anion exchange reaction, and the purpose of refrigeration under an environment of 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.

[0020] Acetonitrile is used as a solvent in the preparation of the quaternary ammonium salt-Br ionic liquid and the preparation of the quaternary ammonium salt-tetrafluoroboric acid ionic liquid, and its amount is at least sufficient to ensure the reaction.

[0021] According to a fourth aspect disclosed in the present invention, the present invention provides a polyionic liquid material prepared by the above method.

[0022] According to a fifth aspect disclosed in the present invention, the present invention provides a flexible and stretchable nanogenerator prepared using the above-mentioned polyionic liquid material.

[0023] 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 photoelectric conversion polyionic liquid materials. Specifically, the nanogenerator of the present invention is prepared by using a new type of polyionic liquid material, which realizes stretchability, a tensile strength of 4.61MPa, an elongation at break of 1043.08%, an elastic modulus of 0.78MPa, and its output electrical performance can be effectively adjusted by adjusting the stretching rate. It can be widely used in smart flexible wearable devices, health testing and other fields, and has great application prospects.

[0024] In a feasible implementation manner, the nanogenerator comprises a five-layer structure arranged sequentially from top to bottom; The first and fifth layers are elastic transparent films; the second and fourth layers are liquid metal conductive layers; the third layer is polyionic liquid material; The elastic transparent film is a modified thermoplastic polyurethane elastomer.

[0025] 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 photoelectric conversion polyionic liquid materials; wherein, the types of "photoisomerization units" and "dipole units" of the polyionic liquid materials are replaceable, such as: spiropyran derivatives with different substituents, spirooxazine derivatives, azobenzene derivatives, quaternary ammonium salt ionic liquids, imidazolium 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 and acrylic resins with different molecular structures, etc.

[0026] In a feasible implementation, the elastic transparent film is a modified thermoplastic polyurethane elastomer, and its thickness is 100 μm. The specific parameters of the modified thermoplastic polyurethane elastomer material are: Young's modulus: 10 MPa; gram weight: 58 g / m 2 ; Elongation at break: 1500%; Elastic range: 100%; Softening temperature: 120℃; Hot working temperature: 130-150℃.

[0027] In a feasible implementation manner, the liquid metal conductive slurry is prepared by the following method: Preparation of 1,4-butanediol type polyurethane: take polytetramethylene ether glycol and hexamethylene diisocyanate, react at 25-30°C for 25-35min under magnetic stirring, heat to 55-65°C for 25-35min, then heat to 75-85°C for 25-35min; then add 1,4-butanediol, react at 85-105°C for 2-4h, then heat to 115-125°C for 1-2h to obtain 1,4-butanediol type polyurethane; Preparation of solution I: taking the 1,4-butanediol type polyurethane, polyethylene oxide and anhydrous ethanol, stirring them magnetically at 75-85° C. until they are completely dissolved, to obtain solution I; Preparation of solution II: taking liquid metal and anhydrous ethanol, ultrasonically dispersing them uniformly and then standing them, pouring out the upper clear liquid after the solution is stable, and keeping the lower suspension liquid for later use, to obtain solution II; the liquid metal is a gallium-indium alloy, and the mass ratio of gallium to indium is 3:1; Preparation of liquid metal conductive slurry: Mix solution I and solution II at 75-85° C. to obtain liquid metal conductive slurry.

[0028] The beneficial effects of adopting the above technical solution are as follows: the present invention prepares a new type of liquid metal slurry through 1,4-butanediol polyurethane, polyethylene oxide and gallium-indium alloy. The slurry has an electrical conductivity of up to 76388.89S and has excellent stretchability.

[0029] In a feasible embodiment, in the preparation of 1,4-butanediol-based polyurethane, the molar ratio of the polytetramethylene ether 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 type polyurethane to polyethylene oxide is 7:3; the solid content of solution I is 0.05-0.1 g / mL; The solid content of the liquid metal in the prepared solution II is 0.7-0.9 g / mL; In the preparation of the liquid metal conductive slurry, the ratio of the total mass of 1,4-butanediol type polyurethane and polyethylene oxide in the solution I to the mass of the liquid metal in the solution II is 1:7-2:7.

[0030] Further, in preparing solution II, the mixture of liquid metal and anhydrous ethanol is placed in an ultrasonic cell disruptor, ultrasonicated at 100-110W ultrasonic power for 25-35min, and then allowed to stand for 10-14h, the upper clear liquid is poured out, and the lower suspension is set aside to obtain solution II; In the preparation of liquid metal conductive slurry, solution I and solution II are mixed, stirred at 75-85° C. using a homogenizer, the stirring time is 5-10 minutes, the stirring speed is 20000-21000 rpm, and the liquid metal conductive slurry is obtained after mixing evenly.

[0031] According to a sixth aspect of the present disclosure, the present invention provides a method for preparing a flexible and stretchable nanogenerator, comprising: Prepare two sets of conductive circuit modified films I: use a microelectronic printer to print the liquid metal conductive paste on an elastic transparent film to obtain a set of conductive circuit modified films I; continue printing on another elastic transparent film to obtain another set of conductive circuit modified films I; Preparation of conductive circuit modified membrane II: adding the polyionic liquid material to solvent B to dissolve to obtain polyionic liquid slurry, and then using a microelectronic printer to print the polyionic liquid slurry onto a group of conductive circuit modified membranes I to obtain conductive circuit modified membrane II; Preparation of a flexible and stretchable nanogenerator: bonding the conductive circuit modified film II to another set of conductive circuit modified films I, and then plastic-sealing them to obtain a flexible and stretchable nanogenerator.

[0032] The beneficial effects of adopting the above technical scheme are as follows: the present invention uses a microelectronic printer to print a conductive circuit and a photoelectric conversion polyionic liquid material onto an elastic transparent film to prepare a method for preparing a flexible stretchable nanogenerator; N-position alcoholic hydroxyl type spiropyran is used as the "photoisomerization unit" of the photoelectric conversion polyionic liquid material; and in the design of the conductive circuit, a reciprocating winding circuit is used to provide a good buffering effect for the stretching process and reduce the damage to the circuit caused by the pulling force.

[0033] In a feasible embodiment, in the preparation of the flexible stretchable nanogenerator, two groups of conductive circuit modified membranes I are prepared, and the liquid metal conductive layer obtained by printing the liquid metal conductive paste with a microelectronic printer in the conductive circuit modified membrane I includes a supporting portion and at least one stretching portion connected as one body; the supporting portion is a planar spiral structure; In the preparation of the conductive circuit modified membrane II, a polyionic liquid slurry is printed onto a support portion of a group of conductive circuit modified membranes I using a microelectronic printer to obtain a conductive circuit modified membrane II; the solvent B is ethanol or ethyl acetate; In the preparation of flexible stretchable nanogenerators, the supporting portion of the conductive circuit modified membrane II overlaps with the supporting portion of another group of conductive circuit modified membranes I; the stretching portion of the conductive circuit modified membrane II and the stretching portion of another group of conductive circuit modified membranes I face in opposite directions.

[0034] Furthermore, in the conductive circuit modified film I, the stretching portion is arranged in a meandering manner along a direction perpendicular to the supporting portion; the stretching portion has a reciprocatingly bent meandering structure.

[0035] The rotary evaporation used in the present invention is carried out under the condition of vacuum degree of 0.06-0.09 MPa; the purpose of the rotary evaporation is to remove the unreacted raw materials, and the temperature is adjusted according to the unreacted raw materials.

[0036] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention synthesizes N-position alcoholic hydroxyl type spiropyran and uses it as the "photoisomerization unit" of the photoelectric 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 can be greatly improved; (2) The present invention prepares a new type of liquid metal slurry by using 1,4-butanediol polyurethane, polyethylene oxide and gallium-indium alloy. The conductivity of the slurry is as high as 76388.89S, which is much higher than the PET film (19819.820S) with Ni-Cu alloy deposited on the surface used in the existing literature, and has excellent stretchability; (3) Compared with the existing photoelectric conversion polyionic liquid nanogenerators, the flexible and stretchable nanogenerator prepared by the present invention has achieved stretchability, with a tensile strength of 4.61 MPa, an elongation at break of 1043.08%, and an elastic modulus of 0.78 MPa. In addition, its output electrical performance can be effectively adjusted by adjusting the stretching rate. It can be used in smart flexible wearable devices, health testing and other fields, and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the ring-opening isomerization of spiropyran; Figure 2 The square resistance is detected by using a RM9010-02 four-probe probe, wherein (a) is a schematic diagram of the square resistance of the liquid metal conductive paste prepared in Example 4 of the present invention; (b) is a schematic diagram of a PET transparent electrode with Ni-Cu alloy deposited on the surface used in the prior art; Figure 3 The flexible stretchable nanogenerator SP prepared in Example 5 of the present invention NOH Schematic diagram of the structure of the conductive circuit modified membrane I of IL-NG; (a) corresponds to the actual picture, and (b) corresponds to the size distribution diagram of the liquid metal conductive layer structure; Figure 4 The flexible stretchable nanogenerator SP prepared in Example 5 of the present invention NOH IL-NG is attached with SP NOH Schematic diagram of the structure of the conductive circuit modified membrane II of the -IL sample; (a) corresponds to the actual picture; (b) corresponds to the SP NOH -IL sample structure size distribution diagram; Figure 5 The flexible stretchable nanogenerator SP prepared in Example 5 of the present invention NOH Physical image (a), bending image (b), torsion image (c), and torsion-post-tension image (d) of IL-NG; Figure 6 The flexible stretchable nanogenerator SP prepared in Example 5 of the present invention NOH Schematic diagram of the stretching process of IL-NG; Figure 7 The flexible stretchable nanogenerator SP prepared in Example 5 of the present invention NOH Stress-strain curve obtained from the IL-NG tensile process test; Figure 8 The flexible stretchable nanogenerator SP prepared in Example 5 of the present invention NOH Output voltage signal diagram of IL-NG at different stretching rates; Fig. 9 The flexible stretchable nanogenerator SP prepared in Example 5 of the present invention NOH Schematic diagram of the reciprocating bending repeating unit in the stretching section of the conductive circuit modified membrane Ⅰ of IL-NG. DETAILED DESCRIPTION

[0038] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0039] Example 1 This embodiment provides an N-hydroxyl spiropyran (SP NOH ), comprising: Preparation of 3-hydroxymethyl-5-nitrosalicylicylaldehyde: 3-chloromethyl-5-nitrosalicylicylaldehyde (7.5 g, 0.035 mol) was dissolved in a mixed solution of 40 mL of acetone and 13.5 mL of deionized water. The solution was heated to reflux at 60 °C for 20 min, and then a 6 mol / L sodium hydroxide solution (5.79 mL) was added dropwise at 60 °C over a period of 35 minutes. The solution was then heated to reflux at 80 °C for 6 h, and then cooled to room temperature. The product was filtered and washed with deionized water to obtain yellow-green crystals (3-hydroxymethyl-5-nitrosalicylicylaldehyde).

[0040]

[0041] Preparation of 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide: 2,3,3-trimethyl-3H-indole (15.923 g, 0.1 mol) and 2-bromoethanol (24.922 g, 0.2 mmol) were dissolved in 300 mL of acetonitrile, reacted and refluxed at 85 °C for 48 h, then the mixture was slowly cooled to room temperature, and the acetonitrile was removed by rotary evaporation at 80 °C; the obtained dark red oil was redissolved in 100 mL of dichloromethane, extracted three times with deionized water (3×200 mL), the aqueous phase was collected, and excess water was removed by rotary evaporation at a vacuum degree of 0.09 MPa and 80 °C for 2.5 h, and then dried in a vacuum oven at 85 °C for 24 h to remove water to obtain a light red solid (1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide).

[0042]

[0043] Preparation of N-alcoholic hydroxyspiropyran: Weigh 3-hydroxymethyl-5-nitrosalicylicylaldehyde (3.943 g, 0.02 mol) and 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide (5.684 g, 0.02 mol) in a 250 mL two-necked bottle, 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 hours to obtain a black solution.

[0044] The black solution was rotary evaporated at 80°C for 40 min under vacuum degree of 0.09 MPa to obtain a dark red viscous product, which was then washed three times with deionized water at 80°C to obtain the alcohol hydroxyl type spiropyran unit SP NOH (1-Hydroxyethyl 3,3-dimethyl-6'-nitro-8'-hydroxymethyl-3H-indoline spirobenzopyran).

[0045]

[0046] Example 2 A method for preparing a quaternary ammonium salt-tetrafluoroborate ionic liquid "dipole unit" (IL) comprises: Preparation of quaternary ammonium salt-Br ionic liquid: Weigh diethanolamine (colorless transparent viscous liquid) (10.514g, 0.10mol) and add it to a 500mL single-necked flask, then add 250mL acetonitrile, and stir at 60°C until there is no stratification; use a syringe to measure n-butyl bromide (28.56g, 0.21mol), slowly inject it into the single-necked flask, reflux and stir at 90°C for 48h to obtain a transparent solution. Then, the transparent solution is first subjected to rotary evaporation at a vacuum degree of 0.09MPa and 80°C for 1h to remove acetonitrile, and then rotary evaporation at 110°C for 30min to remove residual n-butyl bromide, to obtain a slightly light yellow transparent viscous fluid (quaternary ammonium salt-Br ionic liquid).

[0047] 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, and then add 250 mL of acetonitrile, and stir at room temperature (25-30°C) for 24 hours to allow anion exchange reaction to occur to obtain a light yellow solution, which is then placed in a 4°C refrigerator for 24 hours to ensure that the anion exchange reaction occurs thoroughly; the solution is taken out of the refrigerator, and the acetonitrile is removed by rotary evaporation at a vacuum degree of 0.09 MPa and 80°C for 1 hour to obtain a quaternary ammonium salt-tetrafluoroborate ionic liquid unit IL; in addition, 1-ethyl-3-methylimidazolium bromide is not removed and remains in the system.

[0048]

[0049] Example 3 Polyionic liquid materials (SP NOH -IL) preparation method, comprising: Polypropylene glycol (PEG-1000) was vacuum-dried at 103°C for 1 hour, diphenylmethane diisocyanate (MDI) was added, and 1 drop of dibutyltin dilaurate catalyst was added using a syringe at the beginning of the reaction. The reaction was carried out at 60°C for 1 hour, and then the temperature was raised to 80°C for 1 hour, and then SP was added. NOH , react at 90℃ for 1.5h; then add IL, react at 120℃ for 2h, and discharge; the specific material ratio is shown in Table 1: Table 1 SP NOH -IL each raw material addition amount

[0050] Example 4 A method for preparing a liquid metal conductive slurry, comprising: Preparation of 1,4-butanediol type polyurethane: weigh 8 g of polytetramethylene diol (PTMG-1000) with a molecular weight of 1000 g / mol and 1.77 g of hexamethylene diisocyanate (HDI) and add them into a single-mouth pressure bottle, stir magnetically, react at room temperature (25-30°C) for 30 min, heat to 60°C for 30 min, heat to 80°C for 30 min, add 0.18 g of 1,4-butanediol (BDO), react at 100°C for 3 h, heat to 120°C for 1 h, and obtain 1,4-butanediol type polyurethane.

[0051] Preparation of solution I: weigh 0.35 g of 1,4-butanediol polyurethane, 0.15 g of polyethylene oxide (PEO), and 5 mL of anhydrous ethanol in a single-necked bottle, and stir magnetically at 80° C. until completely dissolved to obtain solution I.

[0052] Preparation of 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 put it into a sample bottle with 10 mL of anhydrous ethanol. Place the sample bottle in an ultrasonic cell disruptor (model: SCIENTZ-IID, produced by Ningbo Xinzhi Biotechnology Co., Ltd.) and ultrasonicate for 30 min at 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 later use.

[0053] Preparation of liquid metal conductive slurry: At 80°C, solution I was added to solution II, and stirred for 5 min using a homogenizer (model: S10 portable high-speed homogenizer, produced by Ningbo Xinzhi Biotechnology Co., Ltd., with a tool diameter of 8 mm) at a speed of 20,000 rpm. After complete mixing, liquid metal conductive slurry was obtained.

[0054] The prepared liquid metal conductive slurry was coated on a PTFE mold using a wire rod to obtain a liquid metal film; and the sheet resistance was measured by a RM9010-02 four-probe probe to be 0.056Ω (such as Figure 2 (a)); After calculation, the conductivity of the liquid metal conductive slurry is 76388.899S, and the calculation formula is as follows:

[0055] Wherein, F=D / S, D is the probe spacing of the probe, S is the probe diameter, D and S are both intrinsic parameters of the instrument, in the RM9010-02 four-probe probe: D=1.5mm, S=0.77mm; R is the measured sheet resistance of the liquid metal film, and t is the thickness.

[0056] In addition, a PET transparent electrode with Ni-Cu alloy deposited on its surface (purchased) was selected for comparison, and its sheet resistance was measured by the same method to be 0.185Ω (e.g. Figure 2(b) shows that the electrical conductivity is 19819.820S, which is much lower than the liquid metal conductive slurry prepared by the present invention.

[0057] Example 5 Using polyionic liquid material SP NOH -IL preparation of flexible stretchable nanogenerator SP NOH IL-NG.

[0058] SP NOH The structure and composition of IL-NG: SP NOH IL OH -NG consists of 5 layers in total: from top to bottom, the first and fifth layers (i.e. the two outermost layers) are elastic transparent films (produced by Beijing Rouzhi Technology Co., Ltd., model: Elasink-B2450); the composition of the film is modified thermoplastic polyurethane elastomer TPU (transparent, thickness of 100μm); the specific parameters of the modified thermoplastic polyurethane elastomer material are: Young's modulus: 10MPa; gram weight: 58g / m 2 (50μm); elongation at break: 1500%; elastic range: 100%; softening temperature: 120℃; hot working temperature: 130-150℃; The second and fourth layers from top to bottom (i.e., the interlayer between the two outermost layers and the middle polymer layer) are liquid metal conductive layers; the third layer from top to bottom (i.e., the middle polymer layer) is synthetic SP NOH -IL materials: polyionic liquid materials.

[0059] The above SP NOH The preparation method of IL-NG comprises: Preparation of two sets of conductive circuit modified films I: The self-made liquid metal conductive slurry was printed onto an Elasink-B2450 elastic transparent film using the "dispensing module" of a microelectronic printer (produced by Shanghai Mifang Electronic Technology Co., Ltd., model: MP1100) to obtain a set of conductive circuit modified films I, the thickness of the formed liquid metal conductive layer was about 0.08-0.1mm; repeat this step on another elastic transparent film to obtain another set of conductive circuit modified films I. Printing parameter settings: printing speed is 2mm / s, dispensing pressure is 160Kpa.

[0060] The liquid metal conductive layer obtained by printing the liquid metal conductive paste with a microelectronic printer in the conductive circuit modified film I includes a supporting part and a stretching part connected as one. Figure 3 (a) and Figure 3As shown in (b), the support portion is a planar spiral structure formed by liquid metal slurry in the direction of the planar spiral structure, and is square in shape as a whole. The stretching portion linearly extends from the center of the support portion in a direction perpendicular to the support portion, and after extending out of the support portion, follows Fig. 9 The given repeating unit bends back and forth and stretches in a winding manner.

[0061] Among them, the supporting part of the conductive circuit is used to cover and support the polymer, and the stretching part is used to buffer the force during the stretching process, thereby protecting the entire circuit.

[0062] Preparation of conductive circuit modified membrane II: Synthesize SP NOH -IL sample was dissolved in ethanol or ethyl acetate (3 mL of solvent was used for each 1 g sample), and then printed onto the support of a group of prepared conductive circuit modified membranes I using the "inkjet module" of a microelectronic printer (produced by Shanghai Mifang Electronic Technology Co., Ltd., model: MP1100) to obtain a conductive circuit modified membrane II, and the thickness of the formed polyionic liquid material was about 0.08-0.1 mm, as shown in FIG. Figure 4 (a) and Figure 4 (b) As shown; parameter setting: inkjet voltage is 20V.

[0063] Preparation of flexible stretchable nanogenerator: another set of conductive circuit modified film I is laminated with conductive circuit modified film II, and then plastic-sealed to obtain a flexible stretchable nanogenerator SP NOH IL-NG.

[0064] Specifically, another set of conductive circuit modified film I and conductive circuit modified film II were closely attached (the support parts overlapped, and the stretching parts were respectively oriented in the left and right directions), and were steadily placed in a plastic sealing machine (produced by Zhejiang Daxiang Office Equipment Co., Ltd., model: 330T) for packaging treatment; parameter settings: plastic sealing temperature was 80°C, plastic sealing speed gear was 3 gears, and the plastic sealing process was repeated 3 times to obtain a flexible stretchable nanogenerator SP NOH IL-NG, such as Figure 5 As shown. Figure 5 It can be seen that the flexible stretchable nanogenerator SP prepared by the present invention NOH IL-NG has good flexibility and tensile properties.

[0065] In this experimental example, the flexible stretchable nanogenerator SP prepared in Example 5 NOH IL-NG is subjected to tensile test. The test process and test results are as follows: Figure 6 and Figure 7 As shown in the figure, the SP prepared by the present invention NOHIL-NG achieved stretchability with a tensile strength of 4.61MPa, an elongation at break of 1043.08% and an elastic modulus of 0.78MPa.

[0066] This experiment also tests the photoelectric conversion performance under different stretching rates. The test results are as follows: Figure 8 As shown in Table 2. Figure 8 As can be seen from Table 2, the output electrical properties can be effectively adjusted by adjusting the stretching rate, and it can be used in smart flexible wearable devices, health testing and other fields.

[0067] Table 2 SP NOH IL-NG output open circuit voltage value at different stretching rates

[0068] In summary, the present invention adopts N-position alcoholic hydroxyl type spiropyran as "photoisomerization unit" for the first time to prepare photoelectric conversion polyionic liquid. Compared with the original phenolic hydroxyl type spiropyran, the polymerization reaction activity is greatly improved, the reaction time can be shortened, and the reaction temperature can be reduced from "120℃ reaction 3h" to "90℃ reaction 1.5h"; the liquid metal conductive slurry prepared by the present invention has good film-forming properties, a conductivity of up to 76388.899 S, and excellent stretchability; the present invention realizes the stretchable performance of nanogenerators based on photoelectric conversion polyionic liquid materials for the first time, which can be widely used in smart flexible wearable devices, health testing and other fields, and has great application prospects.

[0069] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An N-hydroxyl spiropyran, characterized in that the structural formula As shown below: 。 2. A method for preparing N-hydroxyl spiropyran, characterized in that: include: Preparation of 3-hydroxymethyl-5-nitrosalicylicaldehyde: dissolving 3-chloromethyl-5-nitrosalicylicaldehyde in a mixed solution of acetone and deionized water, and then heating and reflux at 55-65° C. for 20-30 minutes; then adding alkaline solution dropwise to the above solution at the same temperature until the pH value of the solution reaches 8-10, and then heating and reflux at 75-85° C. for 6-7 hours, cooling to room temperature, filtering, and washing to obtain 3-hydroxymethyl-5-nitrosalicylicaldehyde; Preparation of 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide: dissolving 2,3,3-trimethyl-3H-indole and 2-bromoethanol in acetonitrile, reflux reaction at 80-90° C. for 48-52 hours, cooling to room temperature, and then rotary evaporation to obtain a dark red oil; then dissolving the dark red oil in dichloromethane, extracting with deionized water, collecting the aqueous phase, and then rotary evaporation and vacuum drying to obtain 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide; Preparation of N-alcoholic hydroxy spiropyran: 3-hydroxymethyl-5-nitrosalicylicylaldehyde and 1-hydroxyethyl-2,3,3-trimethyl-3H-indole bromide are mixed, solvent A and catalyst A are added, and the mixture is heated to reflux at 80-90° C. for 8-30 hours under nitrogen protection, and then subjected to rotary evaporation and washing to obtain N-alcoholic hydroxy spiropyran, i.e., 1-hydroxyethyl 3,3-dimethyl-6'-nitro-8'-hydroxymethyl-3H-indoline spirobenzopyran.

3. The method for preparing the N-hydroxyl spiropyran according to claim 2, characterized in that: In the preparation of 3-hydroxymethyl-5-nitrosalicylicaldehyde, the alkaline solution is obtained by dissolving sodium hydroxide or potassium hydroxide in deionized water; the volume ratio of the acetone to the mixed solvent and the total amount of deionized water in 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-alcoholic hydroxy spiropyran, the molar ratio of the 3-hydroxymethyl-5-nitrosalicylicylaldehyde, 1-hydroxyethyl-2,3,3-trimethyl-3H-bromoindole and the catalyst A is 1:1:1; the solvent A is ethanol; and the catalyst A is piperidine or triethylamine.

4. A method for preparing a polyionic liquid material, characterized in that: include: Preparation of quaternary ammonium salt-tetrafluoroborate ionic liquid: Take polypropylene glycol and diphenylmethane diisocyanate respectively, add catalyst B, react at 55-65°C for 1-2h, then heat to 75-85°C for 1-2h; then add the N-position alcohol hydroxy spiropyran described in claim 1, react at 85-95°C for 1-2h; then add the quaternary ammonium salt-tetrafluoroborate ionic liquid, react at 115-125°C for 1-3h to obtain a polyionic liquid material.

5. The method for preparing the polyionic liquid material according to claim 4, characterized in that: The molar ratio of the polypropylene glycol, diphenylmethane diisocyanate, N-position alcohol hydroxyl spiropyran and quaternary ammonium salt-tetrafluoroborate ionic liquid is 2:4:1:1-2:4.1:1:1; the added amount of the catalyst B is 0.01-0.03% of the total mass of the polypropylene glycol, diphenylmethane diisocyanate, N-position alcohol hydroxyl spiropyran and quaternary ammonium salt-tetrafluoroborate ionic liquid; and the catalyst B is dibutyltin dilaurate.

6. The method for preparing the polyionic liquid material according to claim 4, characterized in that: The preparation method of the quaternary ammonium salt-tetrafluoroborate ionic liquid comprises: Preparation of quaternary ammonium salt-Br ionic liquid: diethanolamine and acetonitrile are stirred evenly at 55-65° C., then n-butyl bromide is added, and the mixture is refluxed and stirred at 85-95° C. for 45-55 hours, and then the quaternary ammonium salt-Br ionic liquid is obtained by rotary evaporation; 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 hours, then place at 2-6° C. for 20-30 hours, and then rotary evaporate to obtain the quaternary ammonium salt-tetrafluoroborate ionic liquid.

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

1.

8. A polyionic liquid material prepared by the method according to any one of claims 4 to 7.

9. A flexible and stretchable nanogenerator, characterized in that: The invention comprises the polyionic liquid material as claimed in claim 8.

10. The flexible and stretchable nanogenerator according to claim 9, characterized in that: The nanogenerator comprises a five-layer structure arranged sequentially from top to bottom; The first and fifth layers are elastic transparent films; the second and fourth layers are liquid metal conductive layers; the third layer is polyionic liquid material; The elastic transparent film is a modified thermoplastic polyurethane elastomer.

11. The flexible and stretchable nanogenerator according to claim 10, characterized in that the liquid The metal conductive paste is prepared by the following method: Preparation of 1,4-butanediol type polyurethane: take polytetramethylene ether glycol and hexamethylene diisocyanate, react at 25-30°C for 25-35min under magnetic stirring, heat to 55-65°C for 25-35min, then heat to 75-85°C for 25-35min; then add 1,4-butanediol, react at 85-105°C for 2-4h, then heat to 115-125°C for 1-2h to obtain 1,4-butanediol type polyurethane; Preparation of solution I: taking the 1,4-butanediol type polyurethane, polyethylene oxide and anhydrous ethanol, stirring at 75-85° C. until completely dissolved to obtain solution I; Preparation of solution II: taking liquid metal and anhydrous ethanol, ultrasonically dispersing them uniformly and then standing them, pouring out the upper clear liquid after the solution is stable, and keeping the lower suspension liquid for later use, to obtain solution II; the liquid metal is a gallium-indium alloy, and the mass ratio of gallium to indium is 3:1; Preparation of liquid metal conductive slurry: Mix solution I and solution II at 75-85° C. to obtain liquid metal conductive slurry.

12. The flexible and stretchable nanogenerator according to claim 11, characterized in that: In the preparation of 1,4-butanediol-based polyurethane, the molar ratio of polytetramethylene ether 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 type polyurethane to polyethylene oxide is 7:3; the solid content of solution I is 0.05-0.1 g / mL; The solid content of the liquid metal in the prepared solution II is 0.7-0.9 g / mL; In the preparation of the liquid metal conductive slurry, the ratio of the total mass of 1,4-butanediol type polyurethane and polyethylene oxide in the solution I to the mass of the liquid metal in the solution II is 1:7-2:

7.

13. The method for preparing the flexible and stretchable nanogenerator according to any one of claims 10 to 12, characterized in that: include: Preparing two sets 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 set of conductive circuit modified films I; Continue printing on another elastic transparent film to obtain another set of conductive circuit modified films I; Preparation of conductive circuit modified membrane II: adding the polyionic liquid material to solvent B to dissolve to obtain polyionic liquid slurry, and then using a microelectronic printer to print the polyionic liquid slurry onto a group of conductive circuit modified membranes I to obtain conductive circuit modified membrane II; Preparation of a flexible and stretchable nanogenerator: bonding the conductive circuit modified film II to another set of conductive circuit modified films I, and then plastic-sealing them to obtain a flexible and stretchable nanogenerator.

14. The method for preparing the flexible and stretchable nanogenerator according to claim 13, characterized in that: Two groups of conductive circuit modified films I are prepared, wherein the liquid metal conductive layer in the conductive circuit modified film I is obtained by printing the liquid metal conductive slurry with a microelectronic printer, and the liquid metal conductive layer includes a supporting portion and at least one stretching portion connected as one body; The support portion is in a planar spiral structure; In preparing the conductive circuit modified membrane II, a polyionic liquid slurry is printed onto a support portion of a group of conductive circuit modified membranes I using a microelectronic printer to obtain a conductive circuit modified membrane II; the solvent B is ethanol or ethyl acetate; In preparing the flexible stretchable nanogenerator, the support portion of the conductive circuit modified film II overlaps with the support portion of another set of conductive circuit modified films I; The stretched portion of the conductive circuit modified film II faces the opposite direction to the stretched portion of another group of conductive circuit modified films I.

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