A piezoelectric elastic material and its preparation method and application

Abstract

The present invention provides a piezoelectric elastomer material and its preparation method and application, relating to the technical field of piezoelectric materials. The piezoelectric elastomer material includes piezoelectric molecular crystals and a polymer elastic matrix, the polymer elastic matrix forms an elastic skeleton of a three-dimensional network structure, the piezoelectric molecular crystals are connected to the three-dimensional network structure by hydrogen bonds, and are filled in the pores of the elastic skeleton, the components of the piezoelectric molecular crystals include hexafluoropentanediol or dodecafluorononanediol, the components of the polymer elastic matrix include degradable waterborne polyurethane polymers or degradable polyester polymers, and the mass ratio of the piezoelectric molecular crystals to the polymer elastic matrix is ​​(0.2-3):1. The piezoelectric elastomer material has sufficient strength and hardness, good elasticity and flexibility, high piezoelectric coefficient, excellent biocompatibility, safe degradability or can be excreted from the body through the biological metabolic system, solving the biosafety problems encountered in the application of piezoelectric materials in the biomedical field.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric materials, and in particular to a piezoelectric elastomer material, a preparation method thereof, and applications thereof. Background Art

[0002] Piezoelectric materials are a class of functional materials with unique properties. They can generate electric fields or mechanically deform in response to mechanical stress. Therefore, they have widespread applications in sensors, actuators, and other smart materials. In biomedical engineering, piezoelectric materials can produce effects similar to endogenous electric fields in biological tissues, interacting with biological systems at the cellular level. This allows piezoelectric materials to transmit electrical stimulation to biological cells, thereby influencing and regulating many fundamental physiological processes. Therefore, by applying piezoelectric materials to biological systems, it is possible to artificially regulate life processes, thereby achieving the purpose of auxiliary treatment.

[0003] The application of piezoelectric materials in the biomedical field places strict demands on their performance. Piezoelectric materials need to be able to withstand complex mechanical stresses and deformations while maintaining their piezoelectric properties. This means that piezoelectric materials must not only have sufficient strength and hardness, but also good elasticity and flexibility to adapt to various movements and deformations of the organism. In addition, piezoelectric materials also need to have good biocompatibility to avoid causing adverse reactions or damage to the organism. In order to avoid secondary damage to the organism due to the need to remove the piezoelectric material from the organism, the piezoelectric material must also be safely degradable or be excreted from the body through the biological metabolic system.

[0004] However, existing inorganic piezoelectric materials, piezoelectric polymers and composite piezoelectric elastomers often find it difficult to meet these requirements simultaneously. Although inorganic piezoelectric materials have excellent piezoelectric properties, their biocompatibility and degradability are poor, and they are usually hard and lack flexibility. While piezoelectric polymers such as polyvinylidene fluoride (PVDF) have good flexibility and biocompatibility, their piezoelectricity and degradability still need to be improved. The solid filler particles in the composite piezoelectric elastomer cannot be effectively dispersed in the polymer phase, and because the piezoelectric phase is randomly oriented in the polymer, further polarization treatment is required to achieve the ideal electrical properties. This results in uneven and unstable elastic and mechanical properties of the composite elastomer, which weakens its actual composite effect.

[0005] Therefore, how to make piezoelectric elastomer materials have appropriate strength and hardness, good elasticity and flexibility, excellent biocompatibility, safe degradation or the ability to be excreted from the body through the biological metabolic system is an urgent problem that needs to be solved. Summary of the Invention

[0006] In response to the deficiencies in the prior art, the present invention provides a piezoelectric elastomer material, a preparation method thereof, and an application thereof. The piezoelectric elastomer material has suitable strength and hardness, good elasticity and flexibility, a high piezoelectric coefficient, excellent biocompatibility, and safe degradability or can be excreted from the body through the biological metabolic system, thereby solving the biosafety issues encountered in the application of piezoelectric materials in the biomedical field.

[0007] The specific technical solutions of the present invention are:

[0008] In a first aspect, the present invention provides a piezoelectric elastomer material, comprising piezoelectric molecular crystals and a polymer elastic matrix, wherein the polymer elastic matrix forms an elastic skeleton with a three-dimensional network structure, and the piezoelectric molecular crystals are connected to the three-dimensional network structure of the polymer elastic matrix through hydrogen bonds and filled in the pores of the elastic skeleton. The components of the piezoelectric molecular crystals include hexafluoropentanediol or dodecafluorononanediol, and the components of the polymer elastic matrix are degradable elastic polymers, which include degradable water-based polyurethane polymers or degradable polyester polymers. The mass ratio of the piezoelectric molecular crystals to the polymer elastic matrix is ​​(0.2-3):1.

[0009] Further preferably, the mass ratio of the piezoelectric molecular crystal to the polymer elastic matrix is ​​(1-2):1.

[0010] In one possible embodiment, the soft segment of the degradable waterborne polyurethane polymer includes at least one of polyether and polyester.

[0011] In one possible embodiment, the degradable polyester polymer includes at least one of a random copolyester of ethylene glycol-cyclohexanedimethanol-succinic acid and a random copolyester of ethylene glycol-cyclohexanedimethanol-furandicarboxylic acid.

[0012] In a possible implementation, the piezoelectric coefficient of the piezoelectric elastomer material is greater than 1 pC / N.

[0013] In a possible implementation, the elastic modulus of the piezoelectric elastomer material is 0.5-50 MPa.

[0014] More preferably, the mass ratio of the piezoelectric molecular crystal to the polymer elastic matrix is ​​(1-1.5):1.

[0015] Furthermore, the piezoelectric coefficient of the piezoelectric elastic material is greater than 18 pC / N.

[0016] Furthermore, the elastic modulus of the piezoelectric elastomer material is 2.5-7 Mpa.

[0017] In a possible implementation, the length of the piezoelectric molecular crystal is 0.2-80 μm.

[0018] In a second aspect, the present invention further provides a method for preparing the piezoelectric elastomer material, comprising the following steps:

[0019] S1. A solution of piezoelectric molecules and a solution of a degradable elastic polymer are blended to form a mixed solution, wherein the piezoelectric molecules include hexafluoropentanediol or dodecafluorononanediol, and the degradable elastic polymer includes a degradable waterborne polyurethane polymer or a degradable polyester polymer; in the mixed solution, the mass ratio of the piezoelectric molecules to the degradable elastic polymer is (0.2-3):1;

[0020] S2. The mixed solution in step S1 is subjected to solvent volatilization, crystal growth and drying treatments to form a polymer elastic matrix from the degradable elastic polymer, while piezoelectric molecular crystals spontaneously grow inside the polymer elastic matrix to obtain a piezoelectric elastomer material.

[0021] In a possible embodiment, the solvent of the piezoelectric molecule solution and the degradable elastic polymer solution in step S1 includes at least one of water, ethanol, chloroform and ethyl acetate.

[0022] In a possible embodiment, the mass volume ratio of the piezoelectric molecules to the solvent in the piezoelectric molecule solution in step S1 is 10-600 mg / mL.

[0023] In one possible embodiment, the mass volume ratio of the degradable elastic polymer to the solvent in the degradable elastic polymer solution in step S1 is 100-600 mg / mL.

[0024] In a possible implementation, the process of preparing the piezoelectric molecule solution in step S1 is that the piezoelectric molecules are dissolved in the solvent, and the dissolution temperature is 10-60° C. and the dissolution time is 5-60 min.

[0025] In a possible embodiment, the preparation process of the degradable elastic polymer solution in step S1 is that the degradable elastic polymer is dissolved in the solvent, and the dissolution temperature is 10-60° C. and the time is greater than 1 min.

[0026] In one possible embodiment, the temperature of the blending in step S1 is 10-40°C.

[0027] In one possible embodiment, the blending time in step S1 is 10-60 min.

[0028] In one possible embodiment, the temperature for volatilization of the solvent in step S2 is 30-40°C.

[0029] In one possible embodiment, the time for evaporation of the solvent in step S2 is 6-12 hours.

[0030] In a possible embodiment, the temperature of the crystal growth in step S2 is 10-60°C.

[0031] In one possible embodiment, the crystal growth time in step S2 is 2-6 hours.

[0032] In a possible embodiment, the drying temperature in step S2 is 20-60° C. and the drying time is 12-36 h.

[0033] In a third aspect, the present invention also provides applications of the above-mentioned piezoelectric elastomer material in the fields of biomedicine, wearable devices or piezoelectric generators.

[0034] The above embodiments can be combined arbitrarily based on the common knowledge in this field.

[0035] The reagents and raw materials used in the present invention are commercially available.

[0036] The positive progress effect of the present invention is:

[0037] The piezoelectric elastomer material provided by the present invention not only has suitable strength and hardness, good elasticity and flexibility, high piezoelectric coefficient, excellent biocompatibility, safe degradability or can be excreted from the body through the biological metabolic system, but also has an unconventional piezoelectric coefficient change trend. The piezoelectric coefficient of conventional piezoelectric elastomer materials decreases with the increase of strain, while the piezoelectric coefficient of the piezoelectric elastomer material in the present invention continues to increase with the increase of strain. This not only ensures the piezoelectric stability of the piezoelectric elastomer material under strain conditions, but also increases the fatigue resistance of the device in the long-term strain process. The piezoelectric coefficient of the piezoelectric elastomer material provided by the present invention can be as high as 26.25 pC / N, and the shape of the output piezoelectric response peak of 4000 continuous impact cycles remains basically unchanged. The preparation method of the piezoelectric elastomer material provided by the present invention is simple and safe, and is very suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 These are X-ray diffraction test spectra of hexafluoropentanediol powder, the waterborne polyurethane film prepared in Comparative Example 1, and the piezoelectric elastomer film prepared in Example 2.

[0039] Figure 2 This is a microscope image of the piezoelectric elastomer film prepared in Example 2.

[0040] Figure 3 These are actual images of the piezoelectric elastomer film prepared in Example 2 in different states.

[0041] Figure 4 Graphs showing stress-strain curves of the films prepared in Examples 1-6 and Comparative Example 1.

[0042] Figure 5 Graph showing the Young's modulus data of the films prepared in Examples 1-6 and Comparative Example 1 at break.

[0043] Figure 6 This is a cyclic stress-strain curve of the piezoelectric elastomer film prepared in Example 2.

[0044] Figure 7 Graph showing the piezoelectric coefficient data of the piezoelectric elastomer films prepared in Examples 1-6.

[0045] Figure 8 This is a data diagram of the piezoelectric coefficient of the piezoelectric elastomer film prepared in Example 2 under different strain conditions.

[0046] Figure 9 Graph showing output voltage data of the piezoelectric elastomer films prepared in Examples 1-6.

[0047] Figure 10 Graph showing output current data of the piezoelectric elastomer films prepared in Examples 1-6.

[0048] Figure 11 This is a graph showing the output voltage data of the piezoelectric elastomer film prepared in Example 2 after 4000 continuous impact cycles.

[0049] Figure 12 These are confocal images of the activity and proliferation of mouse preosteoblasts on the films prepared in the blank group, comparative example 1, and example 2.

[0050] Figure 13 These are confocal images of the activity and proliferation of mouse fibroblasts on the films prepared in the blank group, comparative example 1, and example 2.

[0051] Figure 14 The bioactivity data of mouse preosteoblasts at different concentrations were detected by CCK-8 method (24 h).

[0052] Figure 15 The biological activity data of mouse fibroblasts detected by CCK-8 method (24 h) at different concentrations. DETAILED DESCRIPTION

[0053] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only intended to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter ranges described in the present invention. Reasonable variations derived therefrom are still within the scope of protection of the claims of the present invention.

[0054] It should be noted that the endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0055] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventional meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments was carried out in accordance with the protocols and parameters given by the manufacturers.

[0056] In a first aspect, the present invention provides a piezoelectric elastomer material, comprising piezoelectric molecular crystals and a polymer elastic matrix, wherein the polymer elastic matrix forms an elastic skeleton with a three-dimensional network structure, and the piezoelectric molecular crystals are connected to the three-dimensional network structure of the polymer elastic matrix through hydrogen bonds and filled in the pores of the elastic skeleton. The components of the piezoelectric molecular crystals include hexafluoropentanediol or dodecafluorononanediol, and the components of the polymer elastic matrix are degradable elastic polymers, which include degradable water-based polyurethane polymers or degradable polyester polymers. The mass ratio of the piezoelectric molecular crystals to the polymer elastic matrix is ​​(0.2-3):1.

[0057] The piezoelectric elastomer material provided by the present invention adopts molecular crystals formed by crystallization of small molecule hexafluoropentanediol or dodecafluorononanediol as piezoelectric molecular crystals providing piezoelectric effect. The piezoelectric molecular crystals have an ordered two-dimensional hydrogen bond network and asymmetrically distributed F atoms, which work together to enable the piezoelectric elastomer material to have a high piezoelectric coefficient without polarization. A degradable water-based polyurethane polymer or a degradable polyester polymer with excellent elasticity is adopted as an elastic matrix to form a polymer network structure consisting of alternating soft segments and hard segments, providing elasticity and flexibility. The hexafluoropentanediol or dodecafluorononanediol molecules have hydroxyl groups at both ends and have a high binding ability with the degradable water-based polyurethane polymer or the degradable polyester polymer. The ratio of the piezoelectric molecular crystals to the polymer elastic matrix is ​​further optimized. The piezoelectric molecular crystals and the polymer elastic matrix cooperate with each other to make the piezoelectric elastomer material have both good elasticity and flexibility. Good elasticity, flexibility, and appropriate strength and hardness; and the piezoelectric molecular crystals and polymer elastic matrix used in the piezoelectric elastomer material have good biocompatibility, ensuring the overall biocompatibility of the piezoelectric elastomer material; moreover, the water-based polyurethane polymer or polyester polymer used in the piezoelectric elastomer material is also degradable, and the piezoelectric molecular crystals used can be excreted from the body through the biological metabolic system, avoiding secondary damage to the organism due to the need to remove the piezoelectric material from the organism; under the mutual synergistic effect of the piezoelectric molecular crystals and the polymer elastic matrix, the piezoelectric elastomer material of the present invention presents a piezoelectric coefficient change trend that is different from the conventional one. Under normal circumstances, the piezoelectric coefficient of conventional piezoelectric elastomer materials decreases with the increase of strain, while the piezoelectric coefficient of the piezoelectric elastomer material in the present invention continues to increase with the increase of strain within the tensile strain range of 0-40%. The piezoelectric molecular crystals and polymer elastic matrix used in the present invention cooperate with each other, so that the piezoelectric elastomer material has appropriate strength and hardness, good elasticity and flexibility, high piezoelectric coefficient, excellent biocompatibility, safe degradability or can be excreted from the body through the biological metabolic system.

[0058] Further preferably, the mass ratio of the piezoelectric molecular crystal to the polymer elastic matrix is ​​(1-2):1. When the mass ratio of the piezoelectric molecular crystal to the polymer elastic matrix is ​​within the range of (1-2):1, an optimal balance between the piezoelectric properties, tensile properties, and flexibility of the piezoelectric elastomer material can be achieved. A too low ratio reduces the piezoelectric properties of the piezoelectric elastomer material, while a too high ratio easily generates stress concentration areas within the piezoelectric elastomer material, affecting the tensile properties and flexibility of the piezoelectric elastomer material.

[0059] In one possible embodiment, the soft segment of the degradable waterborne polyurethane polymer includes at least one of polyether and polyester. Using a degradable waterborne polyurethane polymer having a soft segment including at least one of polyether and polyester can make the piezoelectric elastic matrix have higher flexibility and elasticity.

[0060] In one possible embodiment, the degradable polyester polymer includes at least one of a random copolyester of ethylene glycol-cyclohexanedimethanol-succinic acid and a random copolyester of ethylene glycol-cyclohexanedimethanol-furandicarboxylic acid. Using at least one of these random copolyesters can provide the piezoelectric elastic matrix with strength, hardness, and flexibility that better matches human skin.

[0061] In one possible implementation, the piezoelectric coefficient of the piezoelectric elastomer material is greater than 1 pC / N.

[0062] In one possible implementation, the elastic modulus of the piezoelectric elastomer material is 0.5-50 MPa.

[0063] More preferably, the mass ratio of the piezoelectric molecular crystal to the polymer elastic matrix is ​​(1-1.5):1. When the mass ratio of the piezoelectric molecular crystal to the polymer elastic matrix is ​​within the range of (1-1.5):1, the piezoelectric elastomer material has strength, hardness, and flexibility that better matches human skin.

[0064] Furthermore, the piezoelectric coefficient of the piezoelectric elastomer material is greater than 18 pC / N. When the piezoelectric coefficient of the piezoelectric elastomer material is greater than 18 pC / N, the piezoelectric elastomer material can respond more sensitively to pressure.

[0065] Furthermore, the elastic modulus of the piezoelectric elastomer material is 2.5-7 Mpa. When the elastic modulus of the piezoelectric elastomer material is 2.5-7 Mpa, the piezoelectric elastomer material can better match human skin tissue.

[0066] In one possible embodiment, the length of the piezoelectric molecular crystal is 0.2-80 μm. When the length of the piezoelectric molecular crystal is within the range of 0.2-80 μm, the piezoelectric molecular crystal can be more evenly filled in the pores of the elastic skeleton.

[0067] In a second aspect, the present invention further provides a method for preparing the piezoelectric elastomer material, comprising the following steps:

[0068] S1. A solution of a piezoelectric molecule and a solution of a degradable elastic polymer are blended to form a mixed solution, wherein the piezoelectric molecule comprises hexafluoropentanediol or dodecafluorononanediol, and the degradable elastic polymer comprises a degradable waterborne polyurethane polymer or a degradable polyester polymer; in the mixed solution, the mass ratio of the piezoelectric molecule to the degradable elastic polymer is (0.2-3):1;

[0069] S2. The mixed solution in step S1 is subjected to solvent volatilization, crystal growth and drying treatments to form a polymer elastic matrix from the degradable elastic polymer, while piezoelectric molecular crystals spontaneously grow inside the polymer elastic matrix to obtain a piezoelectric elastic material.

[0070] The present invention provides a method for preparing a piezoelectric elastomer material. The method first blends a solution of piezoelectric molecules and a solution of a degradable elastic polymer to form a mixed solution. The solvent is then evaporated by drying to form an elastic skeleton having a three-dimensional network structure from the degradable elastic polymer. The piezoelectric molecules grow spontaneously inside the elastic skeleton to form piezoelectric molecular crystals tightly bound to the elastic skeleton. The present invention provides a method for preparing a piezoelectric elastomer. The method does not require the use of toxic organic solvents, making the prepared piezoelectric elastomer safer. The piezoelectric molecular crystals are formed during the molding process of the polymer elastic matrix, resulting in a strong intermolecular interaction between the piezoelectric molecular crystals and the polymer elastic matrix. This also minimizes defects within the piezoelectric elastomer material, which is beneficial to improving the mechanical and piezoelectric properties of the piezoelectric elastomer material. A piezoelectric elastomer material with excellent piezoelectric properties is prepared without the need for polarization.

[0071] In a possible embodiment, the solvent of the solution of piezoelectric molecules and the solution of degradable elastic polymer in step S1 includes at least one of water, ethanol, chloroform and ethyl acetate.

[0072] In one possible embodiment, the mass volume ratio of the piezoelectric molecules to the solvent in the piezoelectric molecule solution in step S1 is 10-600 mg / mL.

[0073] In one possible embodiment, the mass volume ratio of the degradable elastic polymer to the solvent in the solution of the degradable elastic polymer in step S1 is 100-600 mg / mL.

[0074] By controlling the mass-to-volume ratio of the piezoelectric molecules to the solvent and the mass-to-volume ratio of the degradable elastic polymer to the solvent, the thickness of the prepared piezoelectric elastomer material can be controlled.

[0075] In a possible embodiment, the process of preparing the solution of piezoelectric molecules in step S1 is to dissolve the piezoelectric molecules in a solvent at a temperature of 10-60° C. and a time of 5-60 min.

[0076] In a possible embodiment, the preparation process of the degradable elastic polymer solution in step S1 is to dissolve the degradable elastic polymer in a solvent at a temperature of 10-60° C. for more than 1 minute.

[0077] In one possible embodiment, the blending temperature in step S1 is 10-40° C. By controlling the blending temperature, the mixed solution system is kept in a fluid state and the molecular crystals are not precipitated, so that the piezoelectric molecules are retained in the mixed solution.

[0078] In one possible embodiment, the blending time in step S1 is 10-60 min. By controlling the blending time, the piezoelectric molecules and the degradable elastic polymer are uniformly mixed, thereby avoiding prolonging the preparation time of the piezoelectric elastomer material due to excessive blending time.

[0079] In one possible embodiment, the temperature for solvent volatilization in step S2 is 30-40° C. By controlling the temperature for solvent volatilization, the solvent can be controlled to volatilize at a suitable speed and the piezoelectric molecules can be retained inside the piezoelectric elastomer material.

[0080] In one possible embodiment, the solvent volatilization time in step S2 is 6-12 hours. By controlling the solvent volatilization time, it is ensured that most of the solvent evaporates from the mixed solution and no visible solvent residue is left, while also avoiding excessive preparation time due to excessive volatilization time.

[0081] In one possible embodiment, the crystal growth temperature in step S2 is 10-60° C. By controlling the crystal growth temperature, the piezoelectric molecules can be controlled to grow at a suitable speed in the elastic framework and sublimation of some piezoelectric molecular crystals due to excessively high temperature can be avoided.

[0082] In one possible embodiment, the crystal growth time in step S2 is 2-6 hours. By controlling the crystal growth time, on the one hand, the length of the piezoelectric molecular crystal can be controlled, and on the other hand, the piezoelectric molecular crystal can be ensured to be evenly dispersed within the piezoelectric elastomer material and to cover the entire piezoelectric elastomer material.

[0083] In one possible embodiment, the drying temperature in step S2 is 20-60°C and the drying time is 12-36 hours. By controlling the drying temperature and time, the residual solvent is further removed, which is beneficial for improving the electrical and mechanical properties of the piezoelectric elastomer material while also preventing the sublimation of some piezoelectric molecular crystals due to excessively high temperatures.

[0084] In a third aspect, the present invention also provides applications of the above-mentioned piezoelectric elastomer material in the fields of biomedicine, wearable devices or piezoelectric generators.

[0085] The technical solutions of the present invention are further described below with reference to specific examples. All reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment. The instruments used in the examples are also commercially available.

[0086] Example 1

[0087] This embodiment provides a piezoelectric elastomer film, which is prepared by the following preparation method:

[0088] S1. Add 150 mg of hexafluoropentanediol (HFPD) to 1.5 mL of water and shake to dissolve for 10 min to obtain a piezoelectric phase solution;

[0089] S2, 105 g of waterborne polyurethane MR-873A (WPU) was added to 195 mL of water and dissolved to form a polyurethane suspension;

[0090] S3, the piezoelectric phase solution in step S1 and the polyurethane suspension in step S2 are shaken and mixed at 25° C. for 30 min to obtain a piezoelectric precursor solution;

[0091] S4. The piezoelectric precursor solution in step S3 was cast onto a 2.5 cm × 3.8 cm glass slide, and the glass slide was placed on a 40°C heating table and dried for 8 h, and then ventilated and dried for 30 h at 25°C to prepare a piezoelectric elastomer film (HFPD / WPU) with a piezoelectric phase to polymer mass ratio of 0.5:1.

[0092] Example 2

[0093] This embodiment provides a piezoelectric elastomer film, which is prepared by the following preparation method:

[0094] S1. Add 300 mg of hexafluoropentanediol to 1.5 mL of water and shake to dissolve for 10 min to obtain a piezoelectric phase solution;

[0095] S2, 105 g of waterborne polyurethane MR-873A was added to 195 mL of water and dissolved to form a polyurethane suspension;

[0096] S3, mixing the piezoelectric phase solution in step S1 and the polyurethane suspension in step S2 at 25° C. for 30 min to obtain a piezoelectric precursor solution;

[0097] S4. The piezoelectric precursor solution in step S3 is cast on a 2.5 cm × 3.8 cm glass slide, and the glass slide is placed on a 40°C heating table and dried for 8 hours, and then ventilated and dried at 25°C for 30 hours to prepare a piezoelectric elastomer film with a piezoelectric phase to polymer mass ratio of 1:1.

[0098] Example 3

[0099] This embodiment provides a piezoelectric elastomer film, which is prepared by the following preparation method:

[0100] S1. Add 375 mg of hexafluoropentanediol to 1.5 mL of water and shake to dissolve for 10 min to obtain a piezoelectric phase solution;

[0101] S2, 105 g of waterborne polyurethane MR-873A was added to 195 mL of water and dissolved to form a polyurethane suspension;

[0102] S3, mixing the piezoelectric phase solution in step S1 and the polyurethane suspension in step S2 at 25° C. for 30 min to obtain a piezoelectric precursor solution;

[0103] S4. The piezoelectric precursor solution in step S3 is cast on a 2.5 cm × 3.8 cm glass slide, and the glass slide is placed on a 40°C heating table and dried for 8 hours, and then ventilated and dried at 25°C for 30 hours to prepare a piezoelectric elastomer film with a piezoelectric phase to polymer mass ratio of 1.25:1.

[0104] Example 4

[0105] This embodiment provides a piezoelectric elastomer film, which is prepared by the following preparation method:

[0106] S1. Add 450 mg of hexafluoropentanediol to 1.5 mL of water and shake to dissolve for 10 min to obtain a piezoelectric phase solution;

[0107] S2, 105 g of waterborne polyurethane MR-873A was added to 195 mL of water and dissolved to form a polyurethane suspension;

[0108] S3, mixing the piezoelectric phase solution in step S1 and the polyurethane suspension in step S2 at 25° C. for 30 min to obtain a piezoelectric precursor solution;

[0109] S4. The piezoelectric precursor solution in step S3 is cast on a 2.5 cm × 3.8 cm glass slide, and the glass slide is placed on a 40°C heating table and dried for 8 hours, and then ventilated and dried at 25°C for 30 hours to prepare a piezoelectric elastomer film with a piezoelectric phase to polymer mass ratio of 1.5:1.

[0110] Example 5

[0111] This embodiment provides a piezoelectric elastomer film, which is prepared by the following preparation method:

[0112] S1. Add 525 mg of hexafluoropentanediol to 1.5 mL of water and shake for 10 min to obtain a piezoelectric phase solution.

[0113] S2, 105 g of waterborne polyurethane MR-873A was added to 195 mL of water and dissolved to form a polyurethane suspension;

[0114] S3, mixing the piezoelectric phase solution in step S1 and the polyurethane suspension in step S2 at 25° C. for 30 min to obtain a piezoelectric precursor solution;

[0115] S4. The piezoelectric precursor solution in step S3 is cast on a 2.5 cm × 3.8 cm glass slide, and the glass slide is placed on a 40°C heating table and dried for 8 hours, and then ventilated and dried at 25°C for 30 hours to prepare a piezoelectric elastomer film with a piezoelectric phase to polymer mass ratio of 1.75:1.

[0116] Example 6

[0117] This embodiment provides a piezoelectric elastomer film, which is prepared by the following preparation method:

[0118] S1. Add 600 mg of hexafluoropentanediol to 1.5 mL of water and shake for 10 min to obtain a piezoelectric phase solution;

[0119] S2, 105 g of waterborne polyurethane MR-873A was added to 195 mL of water and dissolved to form a polyurethane suspension;

[0120] S3, mixing the piezoelectric phase solution in step S1 and the polyurethane suspension in step S2 at 25° C. for 30 min to obtain a piezoelectric precursor solution;

[0121] S4. The piezoelectric precursor solution in step S3 is cast on a 2.5 cm × 3.8 cm glass slide, and the glass slide is placed on a 40°C heating table and dried for 8 hours, and then ventilated and dried at 25°C for 30 hours to prepare a piezoelectric elastomer film with a piezoelectric phase to polymer mass ratio of 2:1.

[0122] Example 7

[0123] This embodiment provides a piezoelectric elastomer film, which is prepared by the following preparation method:

[0124] S1. Add 100 mg of dodecafluorononanediol to 0.5 mL of 2-butanone and shake for 10 min to dissolve to obtain a piezoelectric phase solution.

[0125] S2, 200 g of random copolyester of ethylene glycol-cyclohexanedimethanol-succinic acid was added to 2 mL of 2-butanone and dissolved to form a random copolyester solution of ethylene glycol-cyclohexanedimethanol-succinic acid;

[0126] S3, mixing the piezoelectric phase solution in step S1 and the random copolyester solution of ethylene glycol-cyclohexanedimethanol-succinic acid in step S2 at 25° C. for 30 min to obtain a piezoelectric precursor solution;

[0127] S4. The piezoelectric precursor solution in step S3 is cast on a 2.5 cm×3.8 cm glass slide, placed in a 25°C environment for ventilation and drying for 48 hours to prepare a piezoelectric elastomer film with a piezoelectric phase to polymer mass ratio of 2:1.

[0128] Comparative Example 1

[0129] This comparative example provides a polyurethane elastomer film, which is prepared by the following preparation method:

[0130] S1. Add 105 g of waterborne polyurethane MR-873A to 195 mL of water and dissolve to form a polyurethane suspension.

[0131] S2. The polyurethane suspension in step S1 was cast onto a 2.5 cm × 3.8 cm glass slide, and the glass slide was placed on a 40°C heating table and dried for 8 h, and then ventilated and dried at 25°C for 30 h to prepare a polyurethane elastomer film.

[0132] The following tests were performed on the piezoelectric elastomer films prepared in Examples 1-7 and Comparative Example 1.

[0133] Preparation of HFPD / WPU piezoelectric devices:

[0134] Aluminum electrode (1×1cm 2 ) were pasted on both sides of the prepared piezoelectric elastomer film and then encapsulated with polyimide (PI) tape. The encapsulated device was subjected to a pressure of 5 kg for 10 minutes.

[0135] XRD test:

[0136] The XRD powder diffractometer (XRD, Germany) was used to scatter the 2 θ The scanning rate is 4° / min.

[0137] Microscope images:

[0138] A metal mirror (NX30T-3M180, Shenzhen AOSVI Optical Instrument Co., Ltd.) was used to observe the crystal phase distribution of the piezoelectric elastomer film.

[0139] Mechanical properties test:

[0140] The mechanical properties of the piezoelectric elastomer films were evaluated using an Inston-5943 tensile testing machine with a test rate / speed set to 1 mm / mm / min. During the experiment, the samples were cut into strips with a width of 4 mm.

[0141] Electrical performance test:

[0142] The relative dielectric constant is ε rThe test was carried out on the DMS 2000 (BALAB) platform, and the dielectric loss factor ( Tanδ ).

[0143] Piezoelectric performance test:

[0144] The piezoelectric coefficient data of the piezoelectric elastomer film were collected using aZJ-6AN quasi-static measuring instrument.

[0145] Piezoelectric output characteristics analysis test:

[0146] To characterize the piezoelectric output performance of the HFPD / WPU film, a linear motor was used to apply different forces at different frequencies. The input force was precisely monitored using an SBT951-T force sensor, and the piezoelectric output voltage and current were recorded using a KAS 6514 ammeter.

[0147] Cytotoxicity assay:

[0148] Spontaneously immortalized mouse calvaria cell line MC3T3-E1 and mouse fibroblast cell line L929 were cultured in complete medium at 37°C and saturated humidity with 5% CO. After culturing for 24 h, the mouse calvaria cell line MC3T3-E1 and mouse fibroblast cell line L929 were in the logarithmic growth phase and 5×10 3 The cells were transferred to a 96-well plate at a density of 10 cells / well and then cultured in a controlled environment in an incubator. The piezoelectric elastomer film solution in each embodiment and comparative example 1 was diluted to a concentration of 1, 5, and 10 μg / mL and added to 96-well plates containing MC3T3-E1 and L929 cells, respectively. After 24 h, the original culture medium was carefully aspirated from the 96-well plate, and each well was washed twice with phosphate-buffered saline (PBS). Then, 100 μL of diluted CCK-8 solution was added to each well. After incubation for 2 h, the optical density (OD) was measured at 450 nm using the MK-3 enzyme-linked immunosorbent assay. The cell activity was calculated as follows:

[0149] V =( OD e - OD o ) / ( OD c - OD o )

[0150] OD e represents the optical density value of the experimental group, OD o represents the optical density value of the blank group, OD cRepresents the optical density value of the control group.

[0151] For live / dead staining, prepare the working staining solution by mixing 1 μL of calcein-AM solution and 3 μL of 1.5 mM propidium iodide (PI) solution in 1 mL of assay buffer. After incubating cells for 24 hours under the same conditions as above, carefully aspirate and discard the culture medium, and wash the cells three times with assay buffer. Then, add the working staining solution, incubate at 37°C in the dark for 15 minutes, and then wash twice with PBS. Live / dead staining images were captured using an M52 inverted fluorescence microscope.

[0152] Test results description:

[0153] Figure 1 The X-ray diffraction test spectra of hexafluoropentanediol powder, the waterborne polyurethane film prepared in Comparative Example 1 and the piezoelectric elastomer film prepared in Example 2 are shown in FIG. θ The vertical axis represents the diffraction peak intensity. As shown in the figure, the piezoelectric elastomer film prepared in Example 2 exhibits a distinct diffraction peak at 19.1°, corresponding to the (012) plane of the hexafluoropentanediol crystals, indicating successful crystallization of hexafluoropentanediol within the piezoelectric elastomer film. Furthermore, a broad peak at approximately 20° is attributed to amorphous diffraction, indicating the presence of waterborne polyurethane.

[0154] Figure 2 This is a microscope image of the piezoelectric elastomer film prepared in Example 2. As can be seen from the image, the length of the hexafluoropentanediol crystals is about 1-40 μm and they are evenly distributed in the piezoelectric elastomer film.

[0155] Figure 3 The images below show the piezoelectric elastomer film prepared in Example 2 in different states. The images, from top to bottom and from left to right, correspond to the piezoelectric elastomer film in its flat, bent, twisted, before stretching, during stretching, and after stretching. As can be seen from the images, the piezoelectric elastomer film prepared in Example 2 can be bent and twisted arbitrarily, demonstrating excellent stretchability.

[0156] Figure 4The stress-strain curves of the films prepared in Examples 1-6 and Comparative Example 1 are shown, with the abscissa representing tensile strain and the ordinate representing tensile stress. As can be seen from the figure, the stress-strain curve of the waterborne polyurethane film prepared in Comparative Example 1 exhibits its unique elastic behavior, with an elongation at break of approximately 400% and no apparent yield point. In contrast, the piezoelectric elastomer films prepared in Examples 1-6 exhibit a more pronounced yield phenomenon as the hexafluoropentanediol crystal content increases. When the ratio of hexafluoropentanediol crystals to waterborne polyurethane is 1:1, the uniform distribution of the hexafluoropentanediol crystals enhances contact and adhesion at the crystal-polyurethane interface, reduces pore formation during stretching, and results in a relatively smooth stress curve.

[0157] Figure 5 The Young's modulus data graph of the films prepared in Examples 1-6 and Comparative Example 1 when they were broken is shown in Figure 1. The horizontal axis represents the film samples with different preparation ratios, and the vertical axis represents the elastic modulus. Studies have shown that the elastic modulus of human skin is between 0.01 and 10 MPa. When the elastic modulus of the piezoelectric elastomer is within a range close to that of human skin, the comfort of wearing the piezoelectric elastomer can be enhanced. Due to the inherent rigidity of hexafluoropentanediol crystals, when the ratio of hexafluoropentanediol crystals to aqueous polyurethane reaches 1.75, the Young's modulus of the piezoelectric elastomer increases significantly, exceeding 20 MPa. Therefore, maintaining the ratio of hexafluoropentanediol crystals to aqueous polyurethane between 1 and 1.5 can achieve an optimal balance between stretchability and Young's modulus of the piezoelectric elastomer film.

[0158] Figure 6 The cyclic stress-strain curve of the piezoelectric elastomer film prepared in Example 2 is shown in Figure 2. The horizontal axis represents the tensile strain and the vertical axis represents the tensile stress. Since the human body will cause deformation of human tissue during exercise, the materials used in wearable devices are required to have an elastic recovery of at least 50% strain. Figure 6 It can be seen that the piezoelectric elastomer film prepared in Example 2 exhibits high elastic recovery when subjected to a stretching cycle test.

[0159] Figure 7 The piezoelectric coefficient data of the piezoelectric elastomer films prepared in Examples 1-6 are shown in the figure. The horizontal axis represents the film samples with different preparation ratios, and the vertical axis represents the piezoelectric coefficient ( d 33 ). As can be seen from the figure, when the ratio of hexafluoropentanediol crystals to waterborne polyurethane is 1:1 and 2:1 respectively, the prepared piezoelectric elastomer shows an increased piezoelectric coefficient ( d 33 )value.

[0160] Figure 8The experimental data and fitting line data of the piezoelectric coefficient of the piezoelectric elastic film prepared in Example 2 under different strain conditions are shown in FIG. The horizontal axis represents the tensile strain and the vertical axis represents the piezoelectric coefficient ( d 33 As shown in the figure, when the tensile strain increases from 0 to 40%, the piezoelectric coefficient of the piezoelectric elastic film gradually increases and has a strong correlation (R 2 =0.99), which may be due to the reduction in the thickness of the elastic matrix around the hexafluoropentanediol crystals, which improves the stress and charge transport efficiency. When the strain exceeds 40%, the piezoelectric coefficient d 33 The value decreases and stabilizes at approximately 10 pC / N over a wide strain range up to 200%, which is sufficient to meet the strain requirements of skin tissue in daily activities.

[0161] Figure 9 Graph showing output voltage data of the piezoelectric elastomer films prepared in Examples 1-6, where the horizontal axis represents time and the vertical axis represents voltage; Figure 10 The output current data graph of the piezoelectric elastomer film prepared in Examples 1-6, with the horizontal axis representing time and the vertical axis representing current. As can be seen from the figure, as the HFPD:WPU ratio increases from 0.5:1 to 1:1, the output voltage and current increase significantly, from 0.049 V to 0.855 V and 0.026 μA to 0.528 μA, respectively. However, as the HFPD content further increases, the output voltage begins to decrease, which may be due to the combined effects of dielectric loss and interface polarization. In addition, the increase in the proportion of piezoelectric molecular crystals reduces the adhesion between the piezoelectric film and the aluminum electrode, resulting in insufficient contact, which hinders the transfer and accumulation of charge; under specific test conditions, when the HFPD:WPU ratio is 1:1, the piezoelectric elastomer film has the best output voltage performance.

[0162] The electrical performance parameters of the films obtained in Examples 1-6 and Comparative Example 1 are shown in Table 1. ε r and d 33 Under the synergistic effect of the ratio of 1:1, the piezoelectric voltage coefficient of the piezoelectric elastic film ( g 33 ) reached 361.47 Vm / N.

[0163] Table 1 Electrical properties of the films obtained in Examples 1-6 and Comparative Example 1

[0164]

[0165] Figure 11This graph shows the output voltage data for the piezoelectric elastomer film prepared in Example 2 after 4000 consecutive shock cycles. The horizontal axis represents the number of shock cycles, and the vertical axis represents the output voltage. As can be seen from the figure, the output voltage increases slightly with the number of shock cycles. This is likely due to the enhanced bonding between the HFPD crystal and the WPU interface under the action of external force, which improves the stress transfer efficiency. Notably, the shape of the response peak remains essentially unchanged after 4000 consecutive shock cycles, demonstrating the excellent durability of the piezoelectric elastomer film.

[0166] Figure 12 Confocal images of the activity and proliferation of mouse preosteoblasts on the films prepared in the blank group, comparative example 1, and example 2 (scale bar is 200 μm). Figure 13 Confocal images (scale bar, 200 µm) show the activity and proliferation of mouse fibroblasts grown on films prepared in the blank group, Comparative Example 1, and Example 2. Green fluorescence indicates live cells, red fluorescence indicates dead cells, and the column labeled "fused" indicates images containing information from both the green and red fluorescence channels. The images show that mouse preosteoblasts and mouse fibroblasts exhibit filopodia, further demonstrating their activity and the non-cytotoxic nature of the piezoelectric elastic film.

[0167] Figure 14 The bioactivity data of mouse preosteoblasts detected by CCK-8 method (24 h) at different concentrations are shown. Figure 15 The following data are the bioactivity data of mouse fibroblasts tested at different concentrations using the CCK-8 assay (24 hours). The horizontal axis represents the concentration of the piezoelectric elastomer film, and the vertical axis represents cell activity. As shown in the figure, the piezoelectric elastomer film prepared in Example 2 exhibits significant biocompatibility with both mouse preosteoblastic cells (MC3TS-E1) and mouse fibroblasts (L929). Even at concentrations as high as 10 mg / ml, cell viability remains above 92%. Furthermore, the water solubility of HFPD facilitates its rapid dissolution and excretion through metabolic processes in the body.

[0168] The above test data show that the piezoelectric elastomer provided by the present invention meets the basic requirements of biocompatibility and biodegradability, and has great application potential in the biomedical field.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A piezoelectric elastic material, characterized in that: The invention comprises a piezoelectric molecular crystal and a polymer elastic matrix, wherein the polymer elastic matrix forms an elastic skeleton of a three-dimensional network structure, the piezoelectric molecular crystal is connected to the three-dimensional network structure of the polymer elastic matrix through hydrogen bonds and is filled in the pores of the elastic skeleton, the components of the piezoelectric molecular crystal include hexafluoropentanediol or dodecafluorononanediol, the components of the polymer elastic matrix are degradable elastic polymers, and the degradable elastic polymers include degradable waterborne polyurethane polymers or degradable polyester polymers, the mass ratio of the piezoelectric molecular crystal to the polymer elastic matrix is ​​(1-2):1, and the piezoelectric coefficient of the piezoelectric elastomer material is 1.1%. d 33 The length of the piezoelectric molecular crystal increases continuously with the increase of strain within the tensile strain range of 0-40%, and the length of the piezoelectric molecular crystal is 0.2-80 μm.

2. The piezoelectric elastomer material according to claim 1, characterized in that The soft segment of the degradable waterborne polyurethane polymer comprises at least one of polyether and polyester; And / or, the degradable polyester polymer includes at least one of a random copolyester of ethylene glycol-cyclohexanedimethanol-succinic acid and a random copolyester of ethylene glycol-cyclohexanedimethanol-furandicarboxylic acid; and / or, the piezoelectric coefficient of the piezoelectric elastomer material is greater than 1 pC / N; And / or, the elastic modulus of the piezoelectric elastomer material is 0.5-50 MPa.

3. The piezoelectric elastomer material according to claim 2, characterized in that The piezoelectric coefficient of the piezoelectric elastic material is greater than 18 pC / N; And / or, the elastic modulus of the piezoelectric elastomer material is 2.5-7 Mpa.

4. A method for preparing the piezoelectric elastomer material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. A solution of a piezoelectric molecule and a solution of a degradable elastic polymer are blended to form a mixed solution, wherein the piezoelectric molecule comprises hexafluoropentanediol or dodecafluorononanediol, and the degradable elastic polymer comprises a degradable waterborne polyurethane polymer or a degradable polyester polymer; in the mixed solution, the mass ratio of the piezoelectric molecule to the degradable elastic polymer is (1-2):1; S2. The mixed solution of step S1 is subjected to solvent volatilization, crystal growth and drying treatments to form a polymer elastic matrix from the degradable elastic polymer, while piezoelectric molecular crystals grow spontaneously inside the polymer elastic matrix to obtain a piezoelectric elastomer material.

5. The method for preparing a piezoelectric elastic material according to claim 4, characterized in that: In step S1, the solvent of the piezoelectric molecule solution and the degradable elastic polymer solution comprises at least one of water, ethanol, chloroform and ethyl acetate; And / or, the mass volume ratio of the piezoelectric molecules to the solvent in the piezoelectric molecule solution in step S1 is 10-600 mg / mL; And / or, in the solution of the degradable elastic polymer in step S1, the mass volume ratio of the degradable elastic polymer to the solvent is 100-600 mg / mL.

6. The method for preparing a piezoelectric elastic material according to claim 5, characterized in that: The process of preparing the piezoelectric molecule solution in step S1 is that the piezoelectric molecule is dissolved in the solvent, and the dissolution temperature is 10-60° C. and the time is 5-60 min; And / or, the preparation process of the degradable elastic polymer solution in step S1 is that the degradable elastic polymer is dissolved in the solvent, and the dissolution temperature is 10-60° C. and the time is greater than 1 min.

7. The method for preparing a piezoelectric elastic material according to claim 4, characterized in that: The blending temperature in step S1 is 10-40°C; And / or, the blending time in step S1 is 10-120 min.

8. The method for preparing a piezoelectric elastic material according to claim 4, wherein: The temperature at which the solvent evaporates in step S2 is 30-40°C; and / or, the time for evaporation of the solvent in step S2 is 6-12 h; And / or, the temperature of the crystal growth in step S2 is 10-60°C; And / or, the crystal growth time in step S2 is 2-6 h; And / or, the drying temperature in step S2 is 20-60° C. and the drying time is 12-36 h.

9. Application of the piezoelectric elastomer material according to any one of claims 1 to 3 in the fields of biomedicine, wearable devices or piezoelectric generators.

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