A light-controlled electromechanical material and its preparation method and application

Abstract

The present invention provides a light-controlled electromechanical material and its preparation method and application, belonging to the field of smart material technology. In the light-controlled electromechanical material prepared by the present invention, spiropyran undergoes a photoisomerization reaction under ultraviolet light irradiation to form a closed-ring spiropyran structure and an open-ring cyanine structure. The two isomeric forms undergo mutual transformation under the conditions of ultraviolet light irradiation of two different wavelengths, and the Young's modulus and strain change, thus having a photoinduced shape memory effect; while the PVDF-based material generates an electrical output when the strain changes, thus having a photoelectric effect; therefore, the present invention combines the photoinduced shape memory property with the piezoelectric property. The prepared light-controlled piezoelectric material not only has a photoinduced shape memory effect, but also has a photoelectric effect. It can be used as both an actuator and a sensor, combining the functions of an actuator and a sensor, overcoming the shortcomings of single-function smart materials.

Description

Technical Field

[0001] The present invention relates to the technical field of smart materials, and in particular to a light-controlled electromechanical material and a preparation method and application thereof. Background Art

[0002] Smart materials can sense and respond to external signals. Therefore, they act as sensors and actuators, working together with electronic control modules on the base structure to form an intelligent structure and electronic system, enabling the integration of sensing, diagnostic, and control functions. Based on the concept of smart structures, smart materials such as piezoelectric materials are used as sensors and actuators and directly attached to the surface of the structure to achieve structural sensing, vibration control, noise control, and stability control, forming a distributed sensing and control system for smart structures. With the development of smart materials, a variety of smart materials have been applied to structural vibration control, including electrostrictive, photostrictive, shape memory alloys, photoinduced shape memory polymers, and piezoelectric materials. These smart materials have their own advantages and disadvantages as actuators. For example, piezoelectric materials, as one of the most widely used smart materials, can be used as transducers, actuators, or sensors in many fields, including bionics, mechanics, aerospace, and architecture, but they are contact-based control. Photoinduced shape memory polymers (PSMs) undergo a significant change in their Young's modulus under ultraviolet light and can recover their pre-deformation shape. Their actuation process involves a narrow temperature range and generates no electric or magnetic fields. Therefore, they have few application restrictions, are contactless, and can withstand large deformations. However, they cannot be used as sensors. Therefore, current smart materials typically only fulfill one function, limiting their widespread application. Summary of the Invention

[0003] The object of the present invention is to provide a light-controlled electromechanical material and a preparation method and application thereof, wherein the light-controlled electromechanical material has the functions of both an actuator and a sensor.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a light-controlled electromechanical material, comprising the following steps:

[0006] performing a first mixing of spiropyran, ethylene vinyl acetate copolymer, and a first organic solvent to obtain a first mixed solution;

[0007] A polyvinylidene fluoride compound and a second organic solvent are mixed for a second time to obtain a second mixed solution; the polyvinylidene fluoride compound includes polyvinylidene fluoride or PVDF-TRFE;

[0008] performing a third mixing of the first mixed solution and the second mixed solution to obtain a blended copolymer;

[0009] The blended copolymer is sequentially dried, pressed, thermally stretched and subjected to electric field polarization to obtain a light-controlled electromechanical material.

[0010] Preferably, the mass ratio of the spiropyran to the ethylene vinyl acetate copolymer is 1:(30-50).

[0011] Preferably, the temperature of the first mixing is 50-90° C.; and the total concentration of spiropyran and ethylene vinyl acetate copolymer in the first mixed solution is 0.1 g / mL.

[0012] Preferably, the temperature of the second mixing is 50-90° C.; and the concentration of the second mixed solution is 0.1 g / mL.

[0013] Preferably, the volume ratio of the first mixed liquid to the second mixed liquid is 1:(1-4).

[0014] Preferably, the temperature of the third mixing is 50-90°C.

[0015] Preferably, the drying temperature is 50-120° C., and the pressing pressure is 1-2T.

[0016] Preferably, the temperature of the thermal stretching is 50-120° C., the stretching deformation rate is 200-400%, and the electric field intensity of the electric field polarization is 100-200 MV / m.

[0017] The present invention provides a light-controlled electromechanical material prepared by the preparation method described in the above technical solution.

[0018] The present invention provides applications of the light-controlled electromechanical material described in the above technical solution in the fields of aerospace, automobiles or medicine.

[0019] The present invention provides a method for preparing a light-controlled electromechanical material, comprising the following steps: first mixing spiropyran, ethylene-vinyl acetate copolymer and a first organic solvent to obtain a first mixed liquid; second mixing a polyvinylidene fluoride vinyl compound and a second organic solvent to obtain a second mixed liquid; the polyvinylidene fluoride vinyl compound comprises polyvinylidene fluoride or PVDF-TRFE; third mixing the first mixed liquid and the second mixed liquid to obtain a blended copolymer; and sequentially drying, pressing, heat stretching and electric field polarization the blended copolymer to obtain the light-controlled electromechanical material. In the light-controlled electromechanical material prepared by the present invention, spiropyran undergoes a photoisomerization reaction under ultraviolet light irradiation to form a closed-ring spiropyran structure and an open-ring mesocyanine structure. The two isomeric forms undergo mutual transformation under the conditions of ultraviolet light irradiation of two different wavelengths (under ultraviolet light irradiation of 365nm wavelength, the transformation occurs from the closed-ring structure to the open-ring structure diagram; under visible light irradiation of 540-560nm wavelength, the transformation occurs from the open-ring structure to the closed-ring structure). The Young's modulus and strain change, thereby having a photoinduced shape memory effect (that is, under ultraviolet light irradiation of a certain wavelength, the Young's modulus and strain change). Young's modulus and strain will change, and when the ultraviolet light disappears, the Young's modulus and strain return to their initial values); PVDF-based materials generate electrical output when the strain changes, thus having a photoelectric effect (i.e., when exposed to light, they deform and generate positive and negative charges on the relative surfaces); therefore, the present invention combines the photoinduced shape memory property with the piezoelectric property. The prepared light-controlled piezoelectric material not only has the photoinduced shape memory effect, but also has the photoelectric effect. It can be used as both an actuator and a sensor, combining the functions of an actuator and a sensor, overcoming the shortcomings of single-function smart materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the preparation method of the light-controlled electromechanical material of the present invention;

[0021] Figure 2 Actual photos of the sample films prepared in Examples 1 to 3; (a) SpvPVD-11; (b) SpvPVD-12; (c) SpvPVD-13;

[0022] Figure 3 This is a photoelectric effect diagram of SpaPVD-11 prepared in Example 1;

[0023] Figure 4 This is a photoelectric effect diagram of SpaPVD-12 prepared in Example 2;

[0024] Figure 5 This is a photoelectric effect diagram of SpaPVD-13 prepared in Example 3;

[0025] Figure 6The results of the uniaxial tensile test of SpaPVD-11 prepared in Example 1 with and without light source are shown in Figure 2. ；

[0026] Figure 7 This is the SEM image of SpvPVD-11 prepared in Example 1;

[0027] Figure 8 This is an SEM image of SpvPVD-12 prepared in Example 2;

[0028] Figure 9 SEM image of SpvPVD-13 prepared in Example 3 . DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing a light-controlled electromechanical material, comprising the following steps:

[0030] performing a first mixing of spiropyran, ethylene vinyl acetate copolymer, and a first organic solvent to obtain a first mixed solution;

[0031] A polyvinylidene fluoride compound and a second organic solvent are mixed for a second time to obtain a second mixed solution; the polyvinylidene fluoride compound includes polyvinylidene fluoride or PVDF-TRFE;

[0032] performing a third mixing of the first mixed solution and the second mixed solution to obtain a blended copolymer;

[0033] The blended copolymer is sequentially dried, pressed, thermally stretched and subjected to electric field polarization to obtain a light-controlled electromechanical material.

[0034] In the present invention, unless otherwise specified, the raw materials required for preparation are all commercially available products well known to those skilled in the art.

[0035] In the present invention, spiropyran, ethylene vinyl acetate copolymer and a first organic solvent are first mixed to obtain a first mixed liquid.

[0036] The present invention has no particular limitation on the sources of the spiropyran and ethylene vinyl acetate copolymer, and any commercially available product known in the art may be used. In the embodiment of the present invention, the ethylene vinyl acetate copolymer is E180F produced by Samsung Electronics of South Korea, and has a vinyl acetate content of 18%.

[0037] In the present invention, the mass ratio of the spiropyran to ethylene vinyl acetate copolymer (EVA) is preferably 1:(30-50), more preferably 1:40.

[0038] In the present invention, the first organic solvent is preferably toluene; the temperature of the first mixing is preferably 50-90°C, more preferably 70-75°C; and the first mixing is preferably performed under stirring. During the first mixing process, the spiropyran molecules are directly physically linked to the ethylene-vinyl acetate copolymer.

[0039] After completing the first mixing, the present invention preferably allows the obtained material to stand for 1 to 2 hours to remove bubbles to obtain a first mixed solution.

[0040] In the present invention, the total concentration of spiropyran and ethylene vinyl acetate copolymer in the first mixed solution is preferably 0.1 g / mL.

[0041] The present invention involves a second mixing of a polyvinylidene fluoride compound and a second organic solvent to produce a second mixed solution. In the present invention, the polyvinylidene fluoride compound comprises polyvinylidene fluoride or PVDF-TRFE. The present invention does not particularly limit the source of the polyvinylidene fluoride compound; any commercially available product known in the art may be used. In an embodiment of the present invention, the polyvinylidene fluoride is HSV900.

[0042] In the present invention, the second organic solvent is preferably dimethylacetamide or dimethylformamide; the temperature of the second mixing is preferably 50-90°C, more preferably 75°C; the time is preferably 1 hour; the concentration of the second mixed solution is preferably 0.1 g / mL; and the second mixing is preferably carried out under stirring conditions.

[0043] After obtaining the first mixed liquid and the second mixed liquid, the present invention performs a third mixing on the first mixed liquid and the second mixed liquid to obtain a blended copolymer. In the present invention, the volume ratio of the first mixed liquid to the second mixed liquid is preferably 1:(1-4), more preferably 1:(2-3); the temperature of the third mixing is preferably 50-90°C, more preferably 75°C; the time is preferably 1 hour; after the third mixing, the present invention preferably allows the resulting material to stand for 1-2 hours; the third mixing is preferably performed under stirring conditions.

[0044] After obtaining the blended copolymer, the present invention sequentially performs drying, pressing, thermal stretching, and electric field poling on the blended copolymer to obtain a light-controlled electromechanical material. In the present invention, the drying temperature is preferably 50-120°C, more preferably 70°C, and the drying time is preferably 2-3 hours. The drying is preferably performed in an oven.

[0045] After the drying is completed, the present invention preferably cools the obtained material naturally and then presses it; the pressing is preferably carried out in a vulcanizer; the pressing pressure is preferably 1-2T; the holding time is preferably 3 minutes; and the number of exhaust times is preferably 2.

[0046] The present invention presses the material into a film by pressing.

[0047] In the present invention, the temperature of the thermal stretching is preferably 50-120°C, more preferably 90°C; the stretching deformation rate is preferably 200-400%, and the stretching speed is preferably 20 mm / min; the present invention increases the content of the β crystal phase in polyvinylidene fluoride or PVDF-TRFE through thermal stretching, thereby improving the electrical output effect.

[0048] In the present invention, the electric field intensity of the electric field polarization is preferably 100 to 200 MV / m. The present invention uses electric field polarization to turn the electric domain, forcing its spontaneous polarization to be oriented, and further improving the electrical output effect of the material.

[0049] The present invention provides a light-controlled electromechanical material prepared by the preparation method described in the above technical solution. In the light-controlled electromechanical material prepared by the present invention, spiropyran, ethylene vinyl acetate copolymer and polyvinylidene fluoride based compound are physically connected.

[0050] The present invention provides the application of the light-controlled electromechanical material of the above technical solution in the fields of aerospace, automobile or medicine. The present invention has no particular limitation on the method of application, and the application can be carried out according to methods well known in the art.

[0051] Figure 1 The flow chart of the preparation method of the light-controlled electromechanical material of the present invention is as follows: Figure 1 As shown, the present invention dissolves spiropyran and ethylene vinyl acetate copolymer (EVA) in toluene and stirs them hydrothermally to uniformity; dissolves PVDF powder in dimethylformamide, places it in a magnetic stirrer, and stirs them hydrothermally to uniformity; mixes the spiropyran-ethylene vinyl acetate copolymer-toluene solution with the PVDF-dimethylformamide solution, places it in a magnetic stirrer, and stirs them hydrothermally to uniformity; the resulting mixture is placed in a drying oven for drying; the resulting product is placed in a vulcanizer and pressed into a film; the resulting product is thermally stretched and polarized under a strong electric field to obtain a light-controlled electromechanical material.

[0052] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] Example 1

[0054] Spiropyran, with the molecular formula N-hydroxyethyl-3,3-dimethyl-6-nitroindoline, ethylene vinyl acetate (EVA), model E180F produced by Samsung, South Korea, with a vinyl acetate content of 18%; polyvinylidene fluoride (PVDF) powder, model HSV900.

[0055] 0.1 g of spiropyran and 4 g of ethylene vinyl acetate copolymer (EVA) were dissolved in 40 mL of toluene solution, stirred evenly at 75°C using a magnetic stirrer, and allowed to stand for 1 h to obtain a spiropyran-ethylene vinyl acetate copolymer-toluene mixture;

[0056] 4 g of PVDF powder was dissolved in 40 mL of dimethylformamide, and the mixture was heated at 70 °C in a magnetic stirrer and stirred for 60 min to obtain a PVDF-dimethylformamide mixture.

[0057] The spiropyran-ethylene vinyl acetate copolymer-toluene mixture and the PVDF-dimethylformamide mixture were mixed at a volume ratio of 1:1, stirred in a magnetic stirrer at 75 °C for 60 min, and allowed to stand for 1 h;

[0058] The mixed solution was placed in a drying oven, dried at 70°C for 2 h, and then cooled naturally;

[0059] The dried material is placed in a vulcanizing machine, pressed into a film at a pressure of 1T, vented twice, and held at pressure for 3 minutes;

[0060] The obtained film was thermally stretched at 90°C at a speed of 20 mm / min to 200% of its original length, and polarized under a strong electric field of 100 MW / m to form a light-controlled electromechanical material, which was recorded as SpvPV-11.

[0061] Example 2

[0062] The only difference from Example 1 is that the volume ratio of the spiropyran-ethylene vinyl acetate copolymer-toluene mixture to the PVDF-dimethylformamide mixture is 1:2, and the prepared light-controlled electromechanical material is recorded as SpvPV-12.

[0063] Example 3

[0064] The only difference from Example 1 is that the volume ratio of the spiropyran-ethylene vinyl acetate copolymer-toluene mixture to the PVDF-dimethylformamide mixture is 1:3, and the prepared light-controlled electromechanical material is recorded as SpvPV-13.

[0065] Characterization and performance testing

[0066] 1) Figure 2The actual pictures of the sample films prepared in Examples 1 to 3; (a) SpvPVD-11; (b) SpvPVD-12; (c) SpvPVD-13; Figure 2 It can be seen that different colors of film products are obtained with different spiropyran contents, and the higher the spiropyran content, the darker the color.

[0067] 2) Example The samples prepared in 1 to 3 were made into 1 cm × 1cm film, thickness is 0.1cm, Building Measurement The circuit is designed with the UV light source at a distance of 20 cm from the sample and connected to an oscilloscope to measure the voltage signal. Photoelectric effect, the resulting photoelectric effect diagrams are as follows Figure 3 、 4 , 5. Figures 3-5 It can be seen that the material prepared by the present invention has a significant photoelectric effect, and the larger the ratio of spiropyran-EVA copolymer to PVDF copolymer, the more significant the photoelectric effect; this shows that changes in the actual ratio of the material will only change its specific performance, and will not affect the material's photoinduced shape memory effect and photoelectric effect.

[0068] 3) Take the SpaPVD-11 sample with the strongest photoelectric effect, prepare it into a 1.5cm×12cm long strip sample, place it on the uniaxial tensile test device, and test its recovery force under UV light irradiation. Repeat multiple cycles within 0~300s (100s as one cycle). The results are shown in Figure 6 ;Depend on Figure 6 It can be seen that the sample elongates when exposed to light and shortens when the light is removed, indicating that it has a shape memory effect.

[0069] 4) The spiropyran-EVA mixture in Example 1, PVDF and the light-controlled electromechanical materials prepared in Examples 1 to 3 were subjected to SEM testing. The results are shown in FIG. Figure 7 ~ 9 ;picture 7 This is the SEM image of SpvPVD-11 prepared in Example 1; 8 This is the SEM image of SpvPVD-12 prepared in Example 2; 9 This is the SEM image of SpvPVD-13 prepared in Example 3; Figure 7 ~ 9 It can be seen that With the spiropyr As the mixing ratio of the N-EVA mixture to PVDF increases, the concentration of crystal particles increases, and the crystal morphology changes from rectangular to square. Shape transformation.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a light-controlled electromechanical material, characterized in that: The following steps are involved: The spiropyran, ethylene vinyl acetate copolymer and a first organic solvent are first mixed to obtain a first mixed solution; the mass ratio of the spiropyran to the ethylene vinyl acetate copolymer is 1:(30-50); the total concentration of the spiropyran and the ethylene vinyl acetate copolymer in the first mixed solution is 0.1 g / mL; A second mixture of a polyvinylidene fluoride compound and a second organic solvent is performed to obtain a second mixed solution; the polyvinylidene fluoride compound includes polyvinylidene fluoride or PVDF-TRFE; and the concentration of the second mixed solution is 0.1 g / mL; performing a third mixing of the first mixed solution and the second mixed solution to obtain a blended copolymer; wherein the volume ratio of the first mixed solution to the second mixed solution is 1:(1-4); The blended copolymer is sequentially dried, pressed, thermally stretched and subjected to electric field polarization to obtain a light-controlled electromechanical material.

2. The preparation method according to claim 1, characterized in that The temperature of the first mixing is 50-90°C.

3. The preparation method according to claim 1, characterized in that The temperature of the second mixing is 50-90°C.

4. The preparation method according to claim 1, characterized in that The temperature of the third mixing is 50-90°C.

5. The preparation method according to claim 1, characterized in that The drying temperature is 50-120° C., and the pressing pressure is 1-2T.

6. The preparation method according to claim 1, characterized in that The temperature of the thermal stretching is 50-120° C., the stretching deformation rate is 200-400%, and the electric field intensity of the electric field polarization is 100-200 MV / m.

7. The light-controlled electromechanical material prepared by the preparation method according to any one of claims 1 to 6.

8. Application of the light-controlled electromechanical material according to claim 7 in the fields of aerospace, automobile or medicine.

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