Zwitter-ion modified acrylate dielectric elastomer film and preparation method thereof

Abstract

The invention discloses a zwitter-ion modified acrylate dielectric elastomer film and a preparation method thereof. Zwitter-ions can be selected from sulfobetaine methacrylate (SBMA), carboxyl betaine methacrylate (CBMA), sulfobetaine acrylamide (SBAA) and the like. The acrylate monomer can be butyl acrylate (BA), dodecyl acrylate (LA), isoamyl acrylate (EHA) and the like. Zwitterions (special compounds which simultaneously carry equal positive and negative charges on the same molecule and are electrically neutral on the whole) are copolymerized into an acrylate dielectric elastomer through photo-initiated free radical polymerization reaction, zwitterionic clusters uniformly distributed in the dielectric elastomer can construct traps for capturing high-energy electrons, the leakage current of the material is reduced, and the dielectric property of the material is improved. And the intrinsic breakdown field strength of the material is improved. In addition, the mutual attraction effect between dipole ions with positive and negative charges in the structure provides driving force for intrinsic self-repairing. And after being electrically and mechanically damaged, the material can be self-recovered, so that the service life of the material is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of dielectric elastomers, in particular to a zwitterion-modified acrylate dielectric elastomer film and a preparation method thereof. BACKGROUND

[0002] Dielectric elastomer (DE) is a kind of smart soft material responding to electric field, which can quickly deform reversibly under the stimulation of external electric field, and realize the mutual conversion between electric energy and mechanical energy. Compared with other smart soft materials (magnetic, light and heat, temperature, pH, etc.), DE has the remarkable characteristics of large driving deformation, fast response speed, high energy density and high electromechanical conversion efficiency, which can well meet the requirements of high efficiency and fast driving of soft robots, and is known as "new generation of artificial muscle".

[0003] The working principle of dielectric elastomer is that when the voltage is loaded, the upper and lower surfaces of the DE material accumulate positive and negative charges respectively, and the heterogeneous charges attract each other to produce Maxwell stress and deform. The basic driving unit composed of dielectric elastomer film and two layers of flexible electrodes is called dielectric elastomer actuator (DEA), which has been widely used in bionic robots, artificial organs, wearable devices, flexible electronics and other fields due to its characteristics of directly doing work without transmission mechanism. Although DEA has been widely used and has achieved certain results in the laboratory, various DE-based actuators have not yet reached the level of commercialization, mainly due to the following reasons: first, without mechanical pre-stretching, most dielectric elastomers have force-electricity instability, and can only achieve small electroactive deformation (<20%) and low output energy density (<20 J / kg), which still has a long way to go compared with the upper limit of biological muscle output energy density (40 J / kg). Although the driving performance of DE material can be significantly improved by pre-stretching, there are problems such as stress relaxation, performance decay and use of rigid frame in the stretched state, which cannot guarantee the stability of driving performance, and the energy conversion efficiency will be greatly reduced. Second, dielectric elastomer materials generally do not have the self-repairing ability of human muscles, and cannot be used once mechanical damage or electrical breakdown occurs, so the service life is short. Therefore, it is urgent to develop self-repairing dielectric elastomer materials and actuators with large deformation and high energy density without pre-stretching to solve the existing problems and meet the actual application requirements. The most common acrylate dielectric elastomer is 3M's VHB series products, which has certain gap in some performance indicators compared with actual application, and the energy loss is large during work, which is also difficult to meet the requirements of high frequency working state and high power density output.

[0004] The document Enhanced energy conversion efficiency in the surface modified BaTiO3 nanoparticles / polyurethane nanocomposites for potential dielectric elastomer generators proposes to blend barium titanate to improve the dielectric constant of the dielectric elastomer and thus improve the energy density of the dielectric elastomer, but this method often brings problems such as serious filler agglomeration, large increase in elastic modulus, mechanical loss and dielectric loss, and large decrease in breakdown field strength, which seriously restricts the improvement of the driving performance of the dielectric elastomer. In the self-repairing of the dielectric elastomer, although the introduction of dynamic covalent bonds can endow the elastomer with self-repairing properties, the introduction of dynamic covalent bonds also sacrifices part of the driving performance of the elastomer. For example, the introduction of dynamic disulfide bonds in the document Dynamic chemical bonds design strategy for fabricating fast room-temperature healable dielectric elastomer with significantly improved actuation performance reduces the driving performance of the dielectric elastomer. How to balance the performance of the dielectric elastomer greatly restricts the application of the dielectric elastomer. SUMMARY

[0005] The present application aims at obtaining a dielectric elastomer material with high breakdown field strength and high energy density and self-repairing properties.

[0006] In order to achieve the purpose of the present application, the following technical solutions are adopted:

[0007] A zwitterion-modified acrylate dielectric elastomer film and a preparation method thereof, characterized in that: the zwitterion is dissolved and dispersed in a methanol solution, then acrylate monomers, a crosslinking agent and a photoinitiator are added, a free radical polymerization reaction is carried out under ultraviolet light, and the polymerized film is dried in a vacuum oven to remove the solvent, thereby obtaining the dielectric elastomer film. The specific preparation steps are as follows:

[0008] Step 1: Because of the amphiphilic characteristics of the zwitterion, the zwitterion is first dissolved in a methanol solvent to obtain a solution;

[0009] Step 2: Acrylate monomers, a crosslinking agent and a photoinitiator are added and stirred uniformly to obtain a mixed reaction liquid;

[0010] Step 3, using the casting method, the mixed solution is cast into a mold and isolated from oxygen under a UV lamp;

[0011] Step 4, the time of the photoinitiated radical polymerization is 30 min, the film is taken out and placed in a vacuum oven to remove residual solvents, thereby obtaining a zwitterion-modified acrylate dielectric elastomer film.

[0012] As a preferred, the zwitterion in step 1 can be a sulfonic betaine or a carboxylic betaine or the like zwitterion compound.

[0013] As a preferred, the acrylate monomer in step 2 can be butyl acrylate (BA), lauryl acrylate (LA), hexafluoroacrylate (HFBA) or the like

[0014] As a preferred, the temperature of the vacuum oven in step 4 can be set to 50-70℃, and the drying time is 12-24 h

[0015] The surface morphology of the film is observed, and the thickness of the film is measured using a thickness gauge, and the standard is that there is no bubble, the thickness is uniform, and the surface is smooth, thereby obtaining a new type of dielectric elastomer film meeting the requirements.

[0016] As a preferred, the dielectric elastomer film is used to make a driver to test its driving characteristics;

[0017] The specific process is as follows:

[0018] A 1mm thick PMMA plate is used as a raw material, a laser cutting machine is used to cut out a circular frame, the inner diameter of the frame is 20mm, and the outer diameter is 100mm, the upper and lower surfaces of the prepared dielectric elastomer film are coated with a circular carbon paste electrode with a diameter of 20mm, and then a dielectric elastomer electric drive performance test device is used, which meets the relevant test standards (Smart Materials and Structures, 2015, 24, 105025), to test the driving characteristics. Different frequencies and voltage values are output using a function generator to drive the driver, and Photoshop software is used to analyze the electrostriction under different parameters, thereby obtaining the force-electricity driving curve of the new type of dielectric elastomer.

[0019] The principle of the application is that an acrylate dielectric elastomer is used as a monomer, a zwitterion is copolymerized to modify and prepare a dielectric elastomer film, the uniformly distributed zwitterion clusters in the dielectric elastomer can construct traps for capturing high-energy electrons, reduce the leakage current of the material, inhibit the initiation and growth of electrical trees, and improve the intrinsic breakdown field strength of the material. In addition, the mutual attraction between the dipole ions with positive and negative charges in the structure provides the driving force for intrinsic self-repair, so that the material can self-repair after being damaged by electricity and machinery, thereby prolonging the service life of the material.

[0020] The application discloses a method for simultaneously improving a breakdown field strength and an energy density and endowing a self-repairing capability of a zwitterionic copolymer modified dielectric elastomer material, and a series of high-breakdown-field-strength and high-energy-density self-repairing dielectric elastomer new materials can be controllably prepared.

[0021] Compared with the prior art, the application has the following advantages:

[0022] The dielectric elastomer new material has high breakdown field strength and self-repairing characteristics, and greatly improves the performance of the dielectric elastomer.

[0023] The dielectric elastomer new material has excellent electric-field-induced deformation performance, fast response, high energy density, easy processing and manufacturing and the like.

[0024] The dielectric elastomer new material has a simple preparation method, a green and pollution-free preparation process and easy large-scale preparation.

[0025] The dielectric elastomer new material introduces a large number of electronic traps through the zwitterions, improves the electron capturing capacity of the material and further improves the breakdown field strength, and the electrostatic interaction force brought by the zwitterions can also simultaneously cope with mechanical damage and electrical damage, thereby prolonging the service life of the material. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The infrared spectra of the dielectric elastomer film P(BA-SB) and the sulfobetaine methacrylate prepared in Example 2.

[0027] Figure 2 The driving schematic diagram and the actual object diagram of the 1wt% zwitterion modified acrylate dielectric elastomer film prepared in Example 2.

[0028] Figure 3 The microscope photos of the mechanical damage self-repairing of the 5wt% zwitterion modified acrylate dielectric elastomer film prepared in Example 4. DETAILED DESCRIPTION

[0029] In order to make the above objectives, characteristics and advantages of the application more apparent, specific embodiments of the application are described in detail below with reference to the drawings. The following content is only an example and description of the concept of the application, and various modifications or supplements or similar ways are adopted by those skilled in the art to replace the described specific embodiments, as long as the concept of the application is not deviated or the scope defined by the claims is exceeded, which should belong to the protection scope of the application.

[0030] Example 1: polybutyl acrylate dielectric elastomer

[0031] The present embodiment adopts a photoinitiated free radical polymerization method to prepare the material, and the specific steps are as follows:

[0032] (1) 30wt% of butyl acrylate (BA), 5wt% of propoxylated neopentyl glycol diacrylate (PNPDA), 62wt% of urethane diacrylate (UDA, catalog name: CN9021), and 3wt% of 2-hydroxy-2-methylphenylpropanone (1173) were mixed and stirred for 15-30min to make the mixed solution uniform. The urethane diacrylate (UDA, catalog name: CN9021) was purchased from Sartomer. Neopentyl glycol propoxy diacrylate (PNPDA, 98%). Butyl acrylate (BA, 99%), 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173, 99%) were all from Shanghai Aladdin

[0033] (2) After the above mixed solution was stirred uniformly, it was cast into a silicone rubber mold, and a photoinitiated free radical polymerization reaction was carried out using an ultraviolet lamp, with an illumination time of 30min, to obtain a dielectric elastomer material

[0034] Performance test

[0035] Dielectric constant measurement: The dielectric elastomer prepared in the present embodiment was cut into a 25mm diameter disc, and was measured on a broadband dielectric and impedance spectrometer instrument at room temperature. The obtained dielectric constant data is shown in Table 1.

[0036] Drive performance characterization: A laser cutting machine was used to cut a 1mm thick PMMA into a circular ring frame with an inner diameter of 20mm and an outer diameter of 100mm. The prepared dielectric elastomer film was coated with a 20mm diameter circular carbon paste electrode on the upper and lower surfaces. Then a self-built dielectric elastomer electric drive performance test device was used to test the drive characteristics, which conforms to the relevant test standards (Smart Materials and Structures, 2015, 24, 105025). Different voltage values were output by a high-voltage power supply to drive the film. Photoshop software was used to analyze the electrostriction under different voltages, and the force-electric drive curve of the new dielectric elastomer was obtained.

[0037] Example 2: Poly(butyl acrylate-sulfobetaine methacrylate) dielectric elastomer

[0038] The present embodiment adopts a photoinitiated free radical polymerization method to prepare the material, and the specific steps are as follows:

[0039] (1) First, 1 wt% of zwitterionic sulfobetaine methacrylate was dissolved in a methanol solution, with a mass ratio of sulfobetaine methacrylate to methanol of 1:20. Then 30 wt% of butyl acrylate (BA), 5 wt% of propoxylated neopentyl glycol diacrylate (PNPDA), 62 wt% of urethane diacrylate (UDA, catalog name: CN9021), and 3 wt% of 2-hydroxy-2-methylphenylpropanone (1173) were mixed and stirred for 15-30 min to make the mixture uniform. The urethane diacrylate (UDA, catalog name: CN9021) was purchased from Sartomer. The neopentyl glycol propoxy diacrylate (PNPDA, 98%) was purchased from Shanghai Aladdin. The butyl acrylate (BA, 99%), 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173, 99%), and zwitterionic sulfobetaine methacrylate (SB, 98%) were all from Shanghai Aladdin

[0040] (2) After the mixed solution was stirred uniformly, it was poured into a silicone rubber mold and subjected to light-induced free radical polymerization using a UV lamp for 30 min to obtain a new dielectric elastomer material

[0041] (3) The obtained new dielectric elastomer material was placed in a vacuum oven at 60°C for 24 h to remove residual solvents, and the final product, a dielectric elastomer film, was obtained.

[0042] Performance test

[0043] Dielectric constant measurement: The new dielectric elastomer prepared in this example was cut into a 25 mm diameter disc, and the dielectric constant was measured on a broadband dielectric and impedance spectrometer at room temperature. The obtained dielectric constant data are shown in Table 1.

[0044] Driving performance characterization: A 1 mm thick PMMA was cut into a circular ring frame with an inner diameter of 20 mm and an outer diameter of 100 mm using a laser cutting machine. The prepared dielectric elastomer film was coated with a 20 mm diameter circular carbon paste electrode on the upper and lower surfaces. Then, a self-built dielectric elastomer electric driving performance test device was used to test the driving characteristics, which conforms to the relevant test standards (Smart Materials and Structures, 2015, 24, 105025). Different voltage values were output by a high-voltage power supply to drive the film. Photoshop software was used to analyze the electrostriction under different voltages, and the force-electricity driving curve of the new dielectric elastomer was obtained.

[0045] Self-repairing property characterization: For the study of self-repairing of mechanical damage, optical microscope was used to observe the self-repairing of the material. The specific experimental scheme is that the prepared dielectric elastomer material is artificially cut with a scalpel to simulate the internal crack caused by environmental factors or external stress in actual use. Then the material is placed in a certain environment for self-repairing, and the repair process is recorded in real time by photographing method. For the study of self-repairing of electrical damage, the method of "repairing electrical tree" is used for observation and study. The dielectric will produce partial discharge under the action of electric field, produce fine cracks, form a small channel, and there are carbon particle traces on the inner wall of the channel, which are in the shape of tree branches. The electrical tree can be observed from the microscope. The self-built device in the laboratory is used to make the zwitterionic modified dielectric elastomer locally discharge inside to form an electrical tree, and the initial electrical tree state is observed and recorded under the microscope. Then let it self-repair, take pictures of the microscope at different lengths of time, and observe the self-repairing changes of the electrical tree.

[0046] Example 3: Poly(butyl acrylate-sulfobetaine methacrylate) dielectric elastomer

[0047] In this example, the light-induced free radical polymerization method is used for material preparation, and the preparation method is similar to that in Example 2.

[0048] In this example, a new dielectric elastomer material is prepared, in which the content of zwitterionic sulfobetaine methacrylate is 3wt%.

[0049] After the above mixed solution is stirred uniformly, it is poured into a silicone rubber mold, and a light-induced free radical polymerization reaction is carried out using a UV lamp, with an illumination time of 30 min, to obtain a dielectric elastomer material

[0050] The obtained new dielectric elastomer material is placed in a vacuum oven at 60°C for 24 h to remove the residual solvent, and the final product dielectric elastomer film is obtained.

[0051] Performance test

[0052] Dielectric constant determination: The new dielectric elastomer prepared in this example is cut into a 25mm diameter disc, and is measured on a wide frequency dielectric and impedance spectrometer instrument, with a test temperature of room temperature. The obtained dielectric constant data is shown in Table 1;

[0053] Drive performance characterization: using a laser cutting machine to cut PMMA with a thickness of 1 mm, a circular ring frame is cut out, the inner diameter of the frame is 20 mm, and the outer diameter is 100 mm. The prepared dielectric elastomer film is coated with a circular carbon paste electrode with a diameter of 20 mm on the upper and lower surfaces. Then, using a self-built dielectric elastomer electric drive performance test device in accordance with the relevant test standards (Smart Materials and Structures, 2015, 24, 105025), the drive characteristics are tested. Different voltage values are output using a high-voltage power supply to drive the film. Photoshop software is used to analyze the electrostriction under different voltages, and the force-electric drive curve of the new dielectric elastomer is obtained.

[0054] Self-repairing property characterization: For the study of self-repairing of mechanical damage, an optical microscope is used to observe the self-repairing of the material. The specific experimental scheme is to use a scalpel to artificially cut the prepared dielectric elastomer material to simulate the situation of internal cracks caused by environmental factors or external stress in actual use. Then the material is placed in a certain environment for self-repairing, and the repair process is recorded in real time by photography. For the study of self-repairing of electrical damage, the "repairing electric tree" method is used for observation and research. The dielectric will locally discharge under the action of electric field, producing fine cracks and forming a small channel, with carbon particle traces on the inner wall of the channel in the form of a tree. The electric tree can be observed under a microscope. Using a self-built device in the laboratory, the zwitterionic modified dielectric elastomer is locally discharged to form an electric tree, and the initial electric tree state is observed and recorded under a microscope. Then let it self-repair, take pictures of the microscope at different times, and observe the self-repairing changes of the electric tree.

[0055] Example 4: Poly(butyl acrylate-sulfobetaine methacrylate) dielectric elastomer

[0056] This example uses a photoinitiated free radical polymerization method to prepare the material, and the preparation method is similar to that in Example 2.

[0057] The dielectric elastomer new material is prepared in this example, and the content of zwitterionic sulfobetaine methacrylate is 5wt%.

[0058] After stirring the above mixed solution uniformly, it is poured into a silicone rubber mold, and a photoinitiated free radical polymerization reaction is carried out using a UV lamp, with an illumination time of 30 min, to obtain a dielectric elastomer material

[0059] The obtained dielectric elastomer new material is placed in a vacuum oven at 60°C for 24h to remove the residual solvent, and the final product dielectric elastomer film is obtained.

[0060] Performance test

[0061] Dielectric constant measurement: The new dielectric elastomer prepared in this example was cut into a 25 mm diameter disc, and measured on a broadband dielectric and impedance spectrometer instrument at room temperature. The obtained dielectric constant data is shown in Table 1.

[0062] Driving performance characterization: PMMA with a thickness of 1 mm was cut into a circular ring frame with an inner diameter of 20 mm and an outer diameter of 100 mm using a laser cutting machine. The prepared dielectric elastomer film was coated with a 20 mm diameter circular carbon paste electrode on the upper and lower surfaces. Subsequently, a self-built dielectric elastomer electric driving performance test device in accordance with the relevant test standards (Smart Materials and Structures, 2015, 24, 105025) was used to test the driving characteristics. Different voltage values were output by a high-voltage power supply to drive the film. Photoshop software was used to analyze the electrostriction under different voltages, and the force-electric driving curve of the new dielectric elastomer was obtained.

[0063] Self-repairing characterization: For the study of self-repairing of mechanical damage, an optical microscope was used to observe the self-repairing of the material. The specific experimental scheme was to artificially cut the prepared dielectric elastomer material with a scalpel to simulate the internal cracking caused by environmental factors or external stress in actual use. Then the material was placed in a certain environment for self-repairing, and the repair process was recorded in real time by photography. For the study of self-repairing of electrical damage, the "repairing electric tree" method was first used for observation and research. The dielectric will locally discharge under the action of an electric field, producing fine cracks and forming a small channel, with carbon particle traces on the inner wall of the channel in the form of a tree. The electric tree can be observed under a microscope. Using a self-built device in the laboratory, the amphoteric ion modified dielectric elastomer was locally discharged inside to form an electric tree, which was observed and recorded under a microscope. Then the self-repairing was allowed to occur, and the microscope pictures at different lengths of time were taken to observe the self-repairing changes of the electric tree.

[0064] Example 5: Poly(isoamyl acrylate-sulfobetaine methacrylate) dielectric elastomer

[0065] In this example, a photoinitiated radical polymerization method was used to prepare the material, and the preparation method was similar to that in Example 2.

[0066] In this example, a new dielectric elastomer material was prepared, and the selected acrylate was isoamyl acrylate. The content of the amphoteric ion sulfobetaine methacrylate was 1 wt%.

[0067] After the above mixed solution was stirred uniformly, it was poured into a silicone rubber mold, and a photoinitiated radical polymerization reaction was carried out using a UV lamp for 30 min to obtain a dielectric elastomer material

[0068] The obtained dielectric elastomer new material was placed in a vacuum oven at 60°C for 24 h to remove residual solvent to obtain the final product dielectric elastomer film.

[0069] Performance test

[0070] Breakdown field strength measurement: A high voltage power supply (BDJC-50 kV, Beijing Beiguang) was used to evaluate the electrical breakdown strength of the elastomer. The film sample was clamped between two electrodes immersed in room temperature silicone oil, and a voltage was applied to the sample at a DC voltage ramp of 500 V / s until a leakage current was detected. Through multiple tests, the electrical breakdown strength was characterized by a two-parameter Weibull distribution function.

[0071] Driving performance characterization: PMMA with a thickness of 1 mm was cut into a circular ring frame with an inner diameter of 20 mm and an outer diameter of 100 mm using a laser cutting machine. The prepared dielectric elastomer film was coated with a circular carbon paste electrode with a diameter of 20 mm on the upper and lower surfaces. Subsequently, a self-built dielectric elastomer electric driving performance test device was used to test the driving characteristics, which conforms to the relevant test standards (Smart Materials and Structures, 2015, 24, 105025). Different voltage values were output by the high voltage power supply to drive the film. The electro-mechanical deformation under different voltages was analyzed using Photoshop software, and the force-electric driving curve of the new dielectric elastomer was obtained.

[0072] Example 6: Poly(dodecyl acrylate-sulfobetaine methacrylate) dielectric elastomer

[0073] This example uses a photoinitiated free radical polymerization method to prepare the material, and the preparation method is similar to that in Example 2.

[0074] This example prepared a new dielectric elastomer material, and the selected acrylate was dodecyl acrylate. The content of the zwitterionic sulfobetaine methacrylate was 1 wt%.

[0075] After the above mixed solution was stirred uniformly, it was cast into a silicone rubber mold, and a photoinitiated free radical polymerization reaction was performed using a UV lamp for 30 min to obtain a dielectric elastomer material

[0076] The obtained dielectric elastomer new material was placed in a vacuum oven at 60°C for 24 h to remove residual solvent to obtain the final product dielectric elastomer film.

[0077] Performance test

[0078] Breakdown field strength measurement: High voltage power supply (BDJC-50 kV, Beijing Beiguang) was used to evaluate the electrical breakdown strength of the elastomer. The film sample was clamped between two electrodes immersed in room temperature silicone oil, and a DC voltage ramp of 500 V / s was applied to the sample until leakage current was detected. Through multiple tests, the electrical breakdown strength was characterized by a two-parameter Weibull distribution function.

[0079] Driving performance characterization: PMMA with a thickness of 1 mm was cut using a laser cutting machine to cut out a circular ring frame with an inner diameter of 20 mm and an outer diameter of 100 mm. The prepared dielectric elastomer film was coated with a circular carbon paste electrode with a diameter of 20 mm on the upper and lower surfaces, and then a self-built dielectric elastomer electric driving performance test device was used to test the driving characteristics. The high voltage power supply was used to output different voltage values to drive the film. The electrically induced deformation under different voltages was analyzed using Photoshop software, and the force-electric driving curve of the new dielectric elastomer was obtained.

[0080] Example 7: Poly(butyl acrylate-carboxybetaine methacrylate) dielectric elastomer

[0081] In this example, a photoinitiated radical polymerization method was used to prepare the material, and the preparation method was similar to that in Example 2.

[0082] In this example, a new dielectric elastomer material was prepared, and the selected acrylate was butyl acrylate. The content of the zwitterionic carboxybetaine methacrylate was 1 wt%.

[0083] After the above mixed solution was stirred uniformly, it was poured into a silicone rubber mold, and a photoinitiated radical polymerization reaction was carried out using a UV lamp for 30 min to obtain a dielectric elastomer material

[0084] The obtained new dielectric elastomer material was placed in a vacuum oven at 60°C for 24 h to remove the residual solvent, and the final product dielectric elastomer film was obtained.

[0085] Performance test

[0086] Breakdown field strength measurement: High voltage power supply (BDJC-50 kV, Beijing Beiguang) was used to evaluate the electrical breakdown strength of the elastomer. The film sample was clamped between two electrodes immersed in room temperature silicone oil, and a DC voltage ramp of 500 V / s was applied to the sample until leakage current was detected. Through multiple tests, the electrical breakdown strength was characterized by a two-parameter Weibull distribution function.

[0087] Driving performance characterization: PMMA with a thickness of 1 mm was cut by a laser cutting machine to cut out a circular frame with an inner diameter of 20 mm and an outer diameter of 100 mm. The prepared dielectric elastomer film was coated with a circular carbon paste electrode with a diameter of 20 mm on the upper and lower surfaces. Subsequently, a self-built dielectric elastomer electric driving performance test device was used to test the driving characteristics, which conforms to the relevant test standards (Smart Materials and Structures, 2015, 24, 105025). The thin film was driven using a high-voltage power supply with different voltage values. The electro- mechanical deformation under different voltages was analyzed using Photoshop software, and the force-electric driving curve of the new dielectric elastomer was obtained.

[0088] Example 8: Poly(butyl acrylate-sulfobetaine acrylamide) dielectric elastomer

[0089] This example uses a photoinitiated free radical polymerization method to prepare the material, and the preparation method is similar to that in Example 2.

[0090] This example prepares a new dielectric elastomer material, and the selected acrylate is butyl acrylate. The content of the zwitterionic sulfobetaine acrylamide is 1wt%.

[0091] After the above mixed solution is stirred uniformly, it is cast into a silicone rubber mold, and a photoinitiated free radical polymerization reaction is performed using a UV lamp. The light irradiation time is 30 min, and the dielectric elastomer material is obtained.

[0092] The obtained dielectric elastomer new material is placed in a vacuum oven at 60°C for 24 h to remove the residual solvent, and the final product dielectric elastomer film is obtained.

[0093] Performance test

[0094] Breakdown field strength determination: A high-voltage power supply (BDJC-50 kV, Beijing Beiguang) was used to evaluate the electrical breakdown strength of the elastomer. The film sample was clamped between two electrodes immersed in room temperature silicone oil, and a DC voltage ramp of 500 V / s was applied to the sample until a leakage current was detected. Through multiple tests, the electrical breakdown strength was characterized using a two-parameter Weibull distribution function.

[0095] Drive performance characterization: using a laser cutting machine to cut PMMA with a thickness of 1 mm, a circular ring frame is cut out, the inner diameter of the frame is 20 mm, and the outer diameter is 100 mm. The prepared dielectric elastomer film is coated with a circular carbon paste electrode with a diameter of 20 mm on the upper and lower surfaces. Then, using a self-built dielectric elastomer electric drive performance test device in accordance with the relevant test standards (Smart Materials and Structures, 2015, 24, 105025), the drive characteristic test is carried out. Using a high-voltage power supply to output different voltage values, the film is driven. Using Photoshop software to analyze the electrostriction under different voltages, the force-electric drive curve of the new dielectric elastomer is obtained.

[0096] Table 1

[0097] Chemical name Dielectric constant Area strain Zwitterionic content Breakdown field strength Example 1 Poly(butyl acrylate) dielectric elastomer 4.58 40% 0 wt% 44 KV / mm Example 2 Poly(butyl acrylate-sulfobetaine methacrylate) dielectric elastomer 4.77 273% 1 wt% 82 KV / mm Example 3 Poly(butyl acrylate-sulfobetaine methacrylate) dielectric elastomer 5.09 124% 3 wt% 95 KV / mm Example 4 Poly(butyl acrylate-sulfobetaine methacrylate) dielectric elastomer 5.78 101% 5 wt% 75 KV / mm Example 5 Poly(isopentyl acrylate-sulfobetaine methacrylate) dielectric elastomer 4.80 215% 1 wt% 60 KV / mm Example 6 Poly(dodecyl acrylate-sulfobetaine methacrylate) dielectric elastomer 4.75 203% 1 wt% 90 KV / mm Example 7 Poly(butyl acrylate-carboxybetaine methacrylate) dielectric elastomer 5.10 150% 1 wt% 82 KV / mm Example 8 Poly(butyl acrylate-sulfobetaine acrylamide) dielectric elastomer 4.92 172% 1 wt% 85 KV / mm

[0098] The above examples are used to explain and illustrate the present application, but not to limit the present application. Any modifications and changes made to the present application within the spirit and protection scope of the claims fall within the protection scope of the present application.

Claims

1. A zwitterion-modified acrylate dielectric elastomer film, characterized in that: Through a special compound that carries equal amounts of positive and negative charges on the same molecule and is electrically neutral as a whole, a free radical polymerization reaction occurs and copolymerizes it into an acrylic dielectric elastomer. By utilizing its functional properties, a dielectric elastomer film with high breakdown electric field strength is obtained.

2. A method for preparing the zwitterionic copolymer-modified high breakdown field strength acrylic dielectric elastomer film according to claim 1, characterized in that: The steps include: Step 1, adding a certain amount of methanol solution to dissolve the zwitterion and uniformly dispersing it by ultrasonication to obtain a zwitterion methanol solution; Step 2: Add acrylate monomer, long-chain crosslinker (CN9021 NS), short-chain crosslinker (PNPDA), and photoinitiator 1173 to the solution, stir evenly, and obtain a mixed reaction solution. Step 3: Isolate the device from oxygen and irradiate with a 365 nm ultraviolet lamp to initiate a free radical polymerization reaction, thereby copolymerizing the zwitterions into the acrylate dielectric elastomer network. Step 4: placing the film in a vacuum oven at 60° C. to remove the methanol solvent, thereby obtaining a zwitterionic copolymer-modified high breakdown field strength acrylic dielectric elastomer film.

3. The preparation method according to claim 2, wherein: The mass ratio of the zwitterion and methanol is 1:10-50, and the added amount of the photoinitiator 1173 is 1%-5% of the total mass.

4. The preparation method according to claim 2, wherein: In step 1, the zwitterion selected can be a betaine type: the side chain carries both a quaternary ammonium ion and a negatively charged functional group (phosphocholine MPC, sulfobetaine SBMA, carboxybetaine CBMA).

5. The preparation method according to claim 2, wherein: In step 2, the acrylate monomer is butyl acrylate BA, isoamyl acrylate EHA, lauryl acrylate LA, fluorinated acrylate HFBA, etc.

6. The preparation method according to claim 2, wherein: In step 3, the UV lamp is used to initiate the free radical polymerization reaction for 30 minutes.

7. The preparation method according to claim 2, wherein: In step 4, the vacuum degree of the vacuum oven is 0.8 KPa, and the drying time is 20-24 hours.

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