Preparation method and application of high-performance electrorheological elastomer

Abstract

The invention relates to a preparation method and application of a high-performance electrorheological elastomer, the continuous phase of the electrorheological elastomer is polydimethylsiloxane, the dispersed phase of the electrorheological elastomer is titanium dioxide and urea layer coated titanoxyl barium oxalate, the mass ratio of the titanium dioxide to the urea layer coated titanoxyl barium oxalate is 1: 1, the mass ratio of the titanium dioxide to the urea layer coated titanoxyl barium oxalate is 1: 1, and the mass ratio of the titanium dioxide to the urea layer coated titanoxyl barium oxalate to the urea layer coated titanoxyl barium oxalate to the urea layer coated titanoxyl barium oxalate is 1: 1. The continuous phase and the dispersed phase are mixed and then are subjected to heating treatment in an electric field with the electric field intensity of 0.2-0.7 kV / mm to obtain the high-performance electrorheological elastomer. The electrorheological elastomer is prepared by taking polydimethylsiloxane as a continuous phase, titanium dioxide nanoparticles and barium titanyloxy oxalate micro-nanoparticles wrapped by a urea layer in a mass ratio of 1: 1 as a dispersed phase and dimethyl silicone oil as an additive through crosslinking and curing under an electric field, and the relative electrorheological effect under the electric field of 2kV / mm can reach 373.75%; the yield reaches 85.7%, and practical application is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of intelligent composite materials, and in particular to a preparation method and application of a high-performance electrorheological elastomer. Background Art

[0002] Electrorheological elastomers (EREs) are intelligent materials that respond to changes in the electric field environment and modify their rheological properties accordingly. They consist of a continuous polymer elastomer phase, a dispersed phase of micro-nanoparticles, and additives. Due to the practical industrial demand for EREs in damping, vibration reduction, control, and sound insulation, current research on EREs focuses primarily on improving the relative ERE effect—that is, increasing the percentage increase in the ERE shear storage modulus under an applied electric field relative to the zero-field condition. Common EREs can be broadly divided into two categories: conventional EREs and giant EREs (GERs). Conventional EREs offer simple preparation processes and low costs, but their relative ERE effects struggle to meet industrial requirements. GERs can achieve a higher relative ERE effect, but their complex preparation processes and high costs hinder their widespread industrial adoption. Improving the ERE response through micro- and mesostructure design while controlling costs and simplifying processes is a key challenge in this field and the primary technical problem addressed by this invention.

[0003] The electrorheological effect is an effect that can influence the arrangement of the dispersed phase in a dielectric suspension or colloid by applying an external electric field, thereby affecting the material's rheological, mechanical, and optical properties. Electrorheological technology, an advanced technology based on the electrorheological effect, boasts low energy consumption, fast response, and reversible switching. For materials exhibiting the electrorheological effect, an applied electric field can rapidly alter both the microstructure and macroscopic properties of the material. Electrorheological fluids (ERFs) are one of the earliest soft materials studied within ER technology. ERFs consist of a continuous phase of insulating oil, a dispersed phase of micro- and nanoparticles, and additives. When an electric field is applied, the micro- and nanoparticles undergo dielectric polarization and align into chains under the influence of Coulomb forces, resulting in a macroscopic increase in viscosity. However, due to their fluidic nature, ERFs have drawbacks such as difficulty in encapsulation and easy sedimentation, limiting their application. Consequently, research on another type of ER material—ER elastomers—has gradually gained traction. ER elastomers consist of a continuous phase of polymer elastomer, a dispersed phase of micro- and nanoparticles, and additives. Electrorheological elastomers (EREs) are solid, effectively overcoming the shortcomings of ER fluids, such as difficulty encapsulating and prone to sedimentation. However, because the continuous phase of the EREs lacks the fluidity of insulating oil, the movement of micro- and nanoparticles within them is significantly restricted. Under an electric field, the micro- and nanoparticles tend to form chains, but they cannot fully form them. This results in a less-than-ideal electrorheological response.

[0004] Currently, the electrorheological response performance of electrorheological elastomers (EREs) is primarily evaluated using the relative ER effect (ERE), which measures the percentage increase in the shear storage modulus after applying an electric field, compared to the shear storage modulus in the absence of an electric field. The most common ERE is one prepared using polydimethylsiloxane as the continuous phase and micro-nanoparticles of a high dielectric constant material as the dispersed phase. The high dielectric constant material in the dispersed phase is often a low-cost and readily available material such as titanium dioxide. While EREs using nanoparticles such as titanium dioxide as the dispersed phase are technologically mature, simple to manufacture, and low-cost, their relative ERE fails to meet industrial needs, particularly at low electric fields, where obtaining high values ​​is difficult.

[0005] After the discovery of the giant electrorheological effect, and particularly after its microscopic mechanism was explained by the surface saturation polarization effect, the inventors' team successfully prepared giant electrorheological elastomers (GERs) and achieved certain applications. Prior art GERs consist of a continuous phase of polydimethylsiloxane, a dispersed phase of barium titanyl oxalate coated with a urea layer, and a dimethyl silicone oil additive. The mixture is then cross-linked and cured in an oven at 50-80°C for 2 to 8 hours to produce an isotropic GER. Due to the high polarizability of barium titanyl oxalate itself and the oriented polarization of the urea polar molecules on its surface, the electrorheological response of GERs is significantly improved compared to traditional EERs. GERs with a dispersed phase of urea-coated barium titanyl oxalate micro-nanoparticles can achieve a very high relative electrorheological effect. However, the yield of giant electrorheological elastomers prepared by existing technologies is low, about 50%. In addition, the synthesis process of titanyl barium oxalate micro-nanoparticles coated with a urea layer requires high experimental conditions. They are currently not available for direct purchase on the market. The cost of laboratory synthesis is estimated to be more than 5 yuan / gram. The dispersed phase is a single urea-coated barium oxalate. Excessive use will increase the overall cost of the giant electrorheological elastomer. In addition, the low yield is not conducive to large-scale industrial preparation and application. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a preparation method of a high-performance electrorheological elastomer and its application.

[0007] The present invention provides a method for preparing a high-performance electrorheological elastomer, wherein the continuous phase of the electrorheological elastomer is polydimethylsiloxane, the dispersed phase of the electrorheological elastomer is titanium dioxide and barium titanyl oxalate wrapped in a urea layer, the mass ratio of the titanium dioxide and the barium titanyl oxalate wrapped in the urea layer is 1:1, and the continuous phase and the dispersed phase are mixed and then heated in an electric field with an electric field strength of 0.2-0.7 kV / mm to obtain the high-performance electrorheological elastomer.

[0008] Furthermore, the preparation method of the urea layer-wrapped barium titanyl oxalate comprises the following steps:

[0009] Step 1-1), 80 g of deionized water was frozen into ice, and 13.4 g of titanium tetrachloride was added to obtain a mixture D;

[0010] Step 1-2), in a water bath heated at 62°C-64°C, the mixture D was added to 100 mL of a 1.41 mol / L barium chloride solution to obtain a solution E;

[0011] Step 1-3), in a water bath heated at 62°C-64°C, 100 mL of a 3 mol / L urea solution was added to 300 mL of a 1.4 mol / L oxalic acid solution to obtain solution F;

[0012] Step 1-4), in a water bath heated at 62°C-64°C, solution E was added to solution F to obtain solution G, and a large amount of ice-water mixture was quickly added;

[0013] Steps 1-5), rinse solution G with deionized water several times until the pH value exceeds 3;

[0014] Step 1-6), removing water from the washed solution G, and freeze-drying it at -50°C for 15 hours to obtain the barium titanyl oxalate coated with the urea layer.

[0015] Furthermore, the titanium dioxide is anatase, and the particle size is 100nm-300nm.

[0016] Furthermore, the particle size of the barium titanyl oxalate coated with the urea layer is 300 nm-5 μm.

[0017] Furthermore, a curing agent and dimethyl silicone oil are added to the continuous phase, ground and mixed, and then the dispersed phase is added and ground and mixed.

[0018] The method for preparing the high-performance electrorheological elastomer provided by the present invention comprises the following steps:

[0019] Step 2-1), add polydimethylsiloxane, curing agent, and dimethyl silicone oil into a grinding device and grind for 5 minutes to fully mix; wherein the mass ratio of polydimethylsiloxane: curing agent: dimethyl silicone oil is 1:0.1:0.923;

[0020] Step 2-2), titanium dioxide powder and urea-coated barium titanyl oxalate powder were added, and the mixture was ground for 10 minutes to mix thoroughly to obtain a precursor; wherein the mass ratio of the mixture obtained in step 2-1): titanium dioxide powder: urea-coated barium titanyl oxalate powder was 1:0.475:0.475;

[0021] Step 2-3), pour the ground precursor into the mold, place it in a vacuum drying oven and evacuate to remove bubbles;

[0022] Step 2-4) Place the mold containing the precursor on the heating table, cover it with a top cover, connect the positive and negative electrodes of a DC high-voltage power supply to the top cover and bottom plate of the mold respectively, place a 200g insulator weight on top of the top cover, turn on the high-voltage power supply switch and apply a voltage of 0.2-0.7kV / mm to form an electric field in the mold;

[0023] Step 2-5) Turn on the heating table switch and set the temperature to 60°C, heat for 2 hours, turn off the heating table and high-voltage power supply after 2 hours, remove the mold, and place it in a dry place to cool for 15 minutes to cool to room temperature. The material in the mold is the high-performance electrorheological elastomer.

[0024] Furthermore, the mass fraction of the barium titanyl oxalate wrapped by the titanium dioxide and urea layers in the precursor is 48.72%.

[0025] Furthermore, the curing agent is a platinum-catalyzed hydrogen-containing siloxane crosslinking agent.

[0026] Furthermore, the electric field strength is 0.5 kV / mm.

[0027] The high-performance electrorheological elastomer provided by the present invention is used in smart materials, such as smart dampers, vibration-damping composite structures, phononic crystals and other fields.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. The present invention uses polydimethylsiloxane as the continuous phase, titanium dioxide nanoparticles and urea-coated barium titanyl oxalate micro-nanoparticles in a 1:1 mass ratio as the dispersed phase, and dimethyl silicone oil as an additive. The electrorheological elastomer prepared by cross-linking and curing under an electric field can achieve a relative electrorheological effect of 373.75% under an electric field of 2kV / mm, significantly improving the electrorheological response compared to traditional electrorheological elastomers containing only a single titanium dioxide dispersed phase. Compared to giant electrorheological elastomers containing only a single urea-coated barium titanyl oxalate dispersed phase, the present invention uses a dual dispersed phase, in which the market price of titanium dioxide is approximately 0.6 yuan / gram, which reduces the use of expensive raw materials for the urea-coated barium titanyl oxalate, significantly reducing costs. At the same time, the technical solution of the present invention simplifies the process of the elastomer preparation process, reduces the uncertainty in the steps, and improves the yield of the sample. Compared to conventional GER curing ovens, which maintain a temperature of 50-80°C and a curing time of 2-8 hours, the present invention utilizes a heated platform for curing, accelerating heat transfer efficiency and maintaining a temperature of 60°C and a curing time of 2 hours, thus reducing uncertainty in the production process. Repeated experiments show that conventional GER curing yields are approximately 50% due to their low storage modulus and susceptibility to breakage, while the present invention achieves a yield of approximately 85.7%.

[0030] 2. The present invention uses electric field pre-regulation to pre-chain two different materials and sizes of micro-nanoparticles within an electrorheological elastomer, thereby enhancing the electrorheological response. The authors found that the electric field strength during cross-linking and curing of the electrorheological elastomer is 0.2-0.7 kV / mm, with 0.5 kV / mm being the most preferred. Compared to other electric field strengths, the electrorheological elastomer obtained by cross-linking and curing at this electric field strength exhibits the best electrorheological response.

[0031] 3. The present invention controls the difference in particle size between titanium dioxide nanoparticles and barium titanyl oxalate micro-nanoparticles wrapped in a urea layer, so that the two produce synergistic and complementary effects under an electric field, thereby enhancing the electrorheological response. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 , flow chart of the method of the present invention;

[0033] Figure 2 , scanning electron microscope images of dispersed phase titanium dioxide and BTRU particles of Example 2;

[0034] Figure 3 , schematic diagram of the mold used in Example 3;

[0035] Figure 4 , photos of samples prepared in Example 4 and Example 5;

[0036] Figure 5, scanning electron microscope image of the cross section of the sample of Example 6;

[0037] Figure 6 , the dielectric constant and dielectric loss of the sample of Example 7;

[0038] Figure 7 , the variation of shear storage modulus of the sample of Example 8 with electric field intensity;

[0039] Figure 8 , the shear loss modulus of the sample in Example 8 changes with the electric field intensity.

[0040] Figure 9 , the changing trend of the average value of the shear storage modulus of Example 8 with the electric field strength and the comparison diagram of the electrorheological modulus and relative electrorheological effect.

[0041] Figure 10 , the effects of barium titanyl oxalate, silicon dioxide, and strontium titanate coated with the urea layer of Example 9 as the second dispersant on the electrorheological properties;

[0042] Figure 11 , the effect of titanium dioxide particle size and the ratio of the two dispersed phases on the electrorheological properties of Example 10. DETAILED DESCRIPTION

[0043] The present invention will be further described below with reference to the examples.

[0044] The preparation process of the high performance electrorheological elastomer of the present invention is as follows: Figure 1 shown.

[0045] Description of the raw materials used in the examples: The continuous phase of the electrorheological elastomer is polydimethylsiloxane (PDMS), specifically SYLGARD 184, a Dow Corning product from the United States. The additive for the electrorheological elastomer is dimethyl silicone oil, specifically PMX-200, a Dow Corning product from the United States, with a kinematic viscosity of 10 cSt. The dispersed phase of the electrorheological elastomer comprises titanium dioxide (TiO2) nanoparticles and barium titanyl oxalate (BTRU) micro-nanoparticles coated with a urea layer. The titanium dioxide in the dispersed phase is anatase with a particle size of approximately 100 to 300 nm and can be purchased directly from any chemical manufacturer.

[0046] Example 1: A two-step coprecipitation method was used to prepare urea-coated barium titanyl oxalate (BTRU) micro-nanoparticles. The specific process is as follows:

[0047] (i) Weigh 29.34 g of barium chloride in a beaker and dissolve it in 100 mL of deionized water to obtain Solution A.

[0048] (ii) Weigh 18 g of urea in a beaker and dissolve it in 100 mL of deionized water to obtain solution B.

[0049] (iii) Weigh 37.83 g of oxalic acid in a beaker and dissolve it in 300 mL of deionized water to obtain Solution C.

[0050] (iv) freezing 80 g of deionized water into ice, and adding 13.4 g of titanium tetrachloride to obtain solution D;

[0051] (v) Adding solution D to solution A in a water bath at 63°C to obtain solution E;

[0052] (vi) In a water bath at 63°C, solution B was added to solution C to obtain solution F.

[0053] (vii) In a water bath heated at 63°C, solution E was added to solution F to obtain solution G, and a large amount of ice-water mixture was quickly added;

[0054] (viii) rinsing solution G with deionized water several times until the pH value exceeds 3;

[0055] (ix) The washed solution G was placed in a funnel and filtered to remove water. The resulting powder was placed in a freeze dryer and freeze-dried at -50°C for 15 hours to obtain BTRU.

[0056] BTRU micro-nanoparticles consist of barium titanyl oxalate (BaTiO(C2O4)2) coated with a urea polar molecular layer. This urea polar molecular layer undergoes surface saturation polarization under an electric field, enhancing the local electric field and the Coulombic forces between the chained micro-nanoparticles. The 63°C water bath heating environment in this example was selected based on experience; in practice, the reaction can be performed within a temperature range of 62-64°C.

[0057] Example 2: Electron microscope image analysis of titanium dioxide nanoparticles and BTRU micro-nanoparticles:

[0058] The titanium dioxide nanoparticles as the dispersed phase and the BTRU micro-nanoparticles obtained in Example 1 were subjected to electron microscope scanning. The electron microscope images are shown in FIG. Figure 2 As shown. Figure 2 Titanium dioxide nanoparticles in a Figure 2 The BTRU micro-nano particles in b all have irregular morphologies, and there is a significant difference in particle size between the two. The particle size of BTRU micro-nano particles ranges from 300nm to 5μm. Figure 2 The difference in particle size between the two can be more clearly seen in the scanning electron microscope image of the mixture of two micro-nanoparticles in c. This certain difference in particle size can play a complementary role when the micro-nanoparticles form chains under the electric field, which is conducive to chain formation. Figure 2 d is Figure 2 Partial magnification of c.

[0059] Example 3: Design and preparation of an electric field pre-regulation mold for an electrorheological elastomer:

[0060] The schematic diagram of the electric field pre-regulation mold is as follows Figure 3 As shown. The mold consists of a chassis 3, a top cover 1, and a plastic bracket 2, wherein the materials of the chassis 3 and the top cover 1 are stainless steel, and the material of the plastic bracket 2 is polyetheretherketone. The chassis as a whole is a cylinder with a diameter of 42mm and a height of 3mm, in which a groove with a diameter of 40mm and a depth of 2mm is processed. The top cover consists of a double-layer cylindrical structure, with the lower cylinder having a diameter of 35mm and a height of 4mm, and the upper cylinder having a diameter of 39mm and a height of 2mm. The outer diameter of the plastic bracket is 40mm and the height is 5mm, and there are four protruding parts inside to support the top cover. During the electric field pre-regulation process, the plastic bracket is placed in the groove of the chassis, the electrorheological elastomer precursor is poured into the groove of the chassis, and after the top cover is placed on the plastic bracket, the gap between the top cover and the chassis is exactly 1mm.

[0061] Example 4: Preparation of an ERE-T electrorheological elastomer containing only a single dispersed phase of titanium dioxide:

[0062] 4-1. Add 2.6 g of PDMS, 0.26 g of curing agent, and 2.4 g of silicone oil to an agate mortar and grind for 5 minutes to mix thoroughly. The curing agent is a platinum-catalyzed hydrogenated siloxane crosslinker.

[0063] 4-2. Add 5 g of titanium dioxide powder and grind for 10 minutes to fully mix to obtain a precursor;

[0064] 4-3. Pour 7.2g of the ground precursor into the groove of the mold bottom plate and place it in a vacuum drying oven. Vacuum and maintain the vacuum state for 7 minutes to remove bubbles.

[0065] 4-4. Place the mold containing the precursor on the heating table and cover it with the top cover. Connect the positive and negative electrodes of the DC high-voltage power supply to the top cover and bottom plate of the mold respectively. Place a 200g insulator weight on top of the top cover. Turn on the high-voltage power supply and adjust the voltage to 0.2kV. The electric field strength in the mold is 0.2kV / mm.

[0066] 4-5. Turn on the heating table and set the temperature to 60°C, heating for 2 hours;

[0067] 4-6. After 2 hours, turn off the heating table and high voltage power supply, remove the mold, and place it in a dry place to cool for 15 minutes to room temperature;

[0068] 4-7. Use a 35 mm diameter punch to remove the disc-shaped sample ERE-T-2 from the mold. See the actual photo. Figure 4 a.

[0069] Example 5: Preparation of ERE-E electrorheological elastomer containing dual dispersed phases of nano-titanium dioxide and BTRU:

[0070] 5-1. Add 2.6 g of PDMS, 0.26 g of curing agent, and 2.4 g of silicone oil to an agate mortar and grind for 5 minutes to mix thoroughly. The curing agent is a platinum-catalyzed hydrogenated siloxane crosslinker.

[0071] 5-2. Add 2.5g titanium dioxide powder and 2.5g BTRU powder, grind for 10 minutes to mix thoroughly;

[0072] 5-3. Pour 7.2g of the ground precursor into the groove of the mold bottom plate and place it in a vacuum drying oven. Vacuum and maintain the vacuum state for 7 minutes to remove bubbles.

[0073] 5-4. Place the mold containing the precursor on the heating table, cover it with the top cover, connect the positive and negative poles of the DC high-voltage power supply to the top cover and bottom plate of the mold respectively, place a 200g insulator weight on top of the top cover, turn on the high-voltage power supply switch and apply appropriate voltage (0.2kV, 0.5kV, 0.7kV) to form an electric field in the mold;

[0074] 5-5. Turn on the heating table and set the temperature to 60℃ and heat for 2 hours.

[0075] 5-6. After 2 hours, turn off the heating table and high voltage power supply, remove the mold, and place it in a dry place to cool for 15 minutes to room temperature;

[0076] 5-7. Use a 35 mm diameter punch to remove the disc-shaped samples from the mold. According to the different electric fields (0.2 kV / mm, 0.5 kV / mm, 0.7 kV / mm), they are named ERE-E-2, ERE-E-5, and ERE-E-7. The actual photos are Figure 4 b. Figure 4 c. Figure 4 d.

[0077] Example 6: Characterization of the anisotropic structure of electrorheological elastomer:

[0078] To characterize the effect of electric field pre-conditioning on promoting twin-particle chain formation, scanning electron microscope images of cross sections were taken for samples ERE-E-2, ERE-E-5, and ERE-E-7. While chain formation is theoretically possible at 0.2 kV / mm, the observed chain formation was not significant. Figure 5 a is the cross section of the ERE-E-2 sample. It can be seen that the electrorheological elastomer cross-linked and cured at 0.2 kV / mm does not form an obvious anisotropic structure. Figure 5b is the cross-section of the ERE-E-5 sample. It can be seen that when the pre-controlled electric field is 0.5 kV / mm, the two particles inside the electrorheological elastomer have begun to form chains along the direction of the electric field, and an obvious anisotropic structure can be seen in the cross-section of the electrorheological elastomer. Figure 5 c is the cross-section of the ERE-E-7 sample. It can be seen that when the pre-controlled electric field increases to 0.7 kV / mm, the anisotropic structure becomes more obvious.

[0079] from Figure 5 It can be seen that when the pre-controlled electric field is greater than or equal to 0.5kV / mm, the curing electric field successfully pre-controlled the particles to form chains. After the elastomer is subjected to an external electric field, the chain-arranged titanium dioxide and BTRU micro-nanoparticles can generate a stronger Coulomb force because the polarized particles are closer in the direction of the electric field, thereby enabling the electrorheological elastomer to obtain a stronger electrorheological response. However, electric field pre-control also has certain negative effects: when the pre-controlled electric field intensity is too high, due to the influence of the anisotropic structure on the continuous phase and the influence of the leakage current on the cross-linking and curing process, the movement range of the particles in the cured elastomer will be limited, thereby affecting its electrorheological response. Therefore, the pre-controlled electric field intensity should not be too high. Above 0.75kV / mm, the leakage current will increase, affecting the cross-linking and curing of polydimethylsiloxane.

[0080] Example 7: Dielectric properties test of electrorheological elastomer:

[0081] The relative dielectric constant and dielectric loss of electrorheological elastomers are closely related to the strength of their electrorheological response. In order to study the effect of pre-controlled electric field on the dielectric properties of elastomers, the dielectric spectra of four samples, ERE-T-2, ERE-E-2, ERE-E-5, and ERE-E-7, were measured in the frequency range of 1Hz to 107Hz using a dielectric impedance spectrometer. The results are as follows: Figure 6 .from Figure 6As shown in the relative dielectric constant data for a, samples ERE-E-2, ERE-E-5, and ERE-E-7 are all dual-particle ER elastomers containing a 1:1 mass ratio of titanium dioxide nanoparticles to BTRU micro-nanoparticles. Their relative dielectric constants are significantly higher than those of single-particle ER elastomers containing only titanium dioxide nanoparticles. This is because the surface saturation polarization effect of the BTRU micro-nanoparticles enhances the electrical polarization of the composite. For dual-particle ER elastomers, the relative dielectric constant of sample ERE-E-5 further increases compared to ERE-E-2 as the pre-controlled electric field increases, reaching a low-frequency relative dielectric constant of 2.39. This is because the dual particles pre-chain under electric field control, and the chain structure is retained after the elastomer cross-links and cures. This brings the micro-nanoparticles closer together, strengthens the local field, and further increases the electrical polarization of the composite. When the pre-controlled electric field is further increased to 0.7kV / mm, the anisotropic structure of the electrorheological elastomer does not undergo further essential changes, so the dielectric constant of the elastomer does not increase further.

[0082] Higher dielectric loss is also required for good electrorheological materials. Figure 6 The dielectric loss data in Figure b show that the dielectric loss of a dual-particle ERE containing a 1:1 mass ratio of titanium dioxide nanoparticles to BTRU nanoparticles is significantly higher than that of a single-particle ERE containing only titanium dioxide nanoparticles. This is because the BTRU nanoparticles have a urea polar molecular layer on their surface. The orientation polarization of this urea polar molecular layer affects the dielectric loss of the material and is a key factor in achieving the giant electrorheological effect. As the pre-conditioned electric field strength increases, the dielectric loss of sample ERE-E-5 further improves compared to ERE-E-2, reaching a low-frequency dielectric loss of 1.16. This is due to the enhanced local field effect caused by the tightly packed chain-like structure of the nanoparticles. As the pre-conditioned electric field increases further, the dielectric loss of sample ERE-E-7 actually decreases compared to sample ERE-E-5, as the anisotropic structure remains unchanged and leakage current negatively impacts the cross-linked PDMS network and the polar molecular layer of the BTRU nanoparticles. Judging from the dielectric spectrum of the electrorheological elastomer, the ERE-E-5 sample has the best electrorheological response performance.

[0083] Example 8: Rheological properties test of electrorheological elastomer:

[0084] Rheological properties, especially the change in shear modulus under an electric field, are the most important indicators for evaluating electrorheological response. The shear modulus of four samples, ERE-T-2, ERE-E-2, ERE-E-5, and ERE-E-7, was tested using a rotational rheometer. The specific test steps are as follows:

[0085] 8-1. Turn on the rotational rheometer, wait for the instrument to complete initialization, assemble the rotor with a diameter of 35 mm, and calibrate it to zero.

[0086] 8-2. Place the electrorheological elastomer sample on the sample stage;

[0087] 8-3. Adjust the gap between the rotor and the sample stage to about 1mm, with the rheometer force sensor data close to 0.5N.

[0088] 8-4. Set the test program: strain 0.01%, angular frequency sweep from 1 rad / s to 100 rad / s, and 18 data points;

[0089] 8-5. Start the program, begin testing, and store the data after the test is completed;

[0090] 8-6. Adjust the electric field strength applied to the electrorheological elastomer and repeat the above steps.

[0091] The test data of shear storage modulus (G') obtained in the above steps are plotted using common logarithmic coordinates, as shown in Figure 7 shown. Figure 7 a. Figure 7 b. Figure 7 c. Figure 7 d is the shear storage modulus test data of four samples, ERE-T-2, ERE-E-2, ERE-E-5, and ERE-E-7. It can be seen that with the increase of the external electric field strength, the shear storage modulus of the electrorheological elastomer gradually increases, which indicates that the elastomer exhibits an electrorheological response. Compared with the single-particle elastomer ERE-T-2, the shear storage modulus of the double-particle elastomer after power is applied is higher. Comparing the samples under different pre-regulated electric fields, the sample ERE-E-5 obtained under the 0.5kV / mm pre-regulated electric field has the highest shear storage modulus under the 2.0kV / mm applied electric field, which indicates that the sample ERE-E-5 has the best electrorheological response.

[0092] The test data of shear loss modulus (G") are plotted using common logarithmic coordinates, such as Figure 8 shown. Figure 8 a. Figure 8 b. Figure 8 c. Figure 8d is the shear loss modulus test data of four samples, ERE-T-2, ERE-E-2, ERE-E-5, and ERE-E-7. It can be seen that with the increase of the external electric field intensity, the shear loss modulus of the electrorheological elastomer also gradually increases, which indicates that the elastomer exhibits an electrorheological response. Compared with the single-particle elastomer ERE-T-2, the shear loss modulus of the dual-particle elastomer after power is applied is higher. Comparing the samples under different pre-regulated electric fields, the sample ERE-E-5 obtained under the 0.5kV / mm pre-regulated electric field has the highest shear loss modulus under the 2.0kV / mm applied electric field, which also indicates that the sample ERE-E-5 has the best electrorheological response.

[0093] Calculate the average value of shear storage modulus at different angular frequencies and plot the change of the average value of shear storage modulus with the applied electric field strength as shown in Figure 9 As shown in Figure a, the electrorheological response of the dual-particle ELE is significantly improved compared to that of the single-particle ELE. Electric field pre-manipulation of the dual-particle chaining successfully enhances the ELE's electrorheological response, with the optimal ELE achieved at a pre-manipulated electric field strength of 0.5 kV / mm.

[0094] Calculate the difference between the shear storage modulus under an applied electric field of 2.0 kV / mm and the shear storage modulus under zero applied electric field, and name the difference as the electrorheological modulus (ΔG'). The size of the electrorheological modulus can be used to evaluate the electrorheological response of the electrorheological elastomer. Figure 9 As can be seen from b, sample ERE-E-5 has the best electromodulus, reaching 222.66 kPa, and has the best performance among the three samples prepared by pre-controlled electric field.

[0095] Calculate the percentage increase of the shear storage modulus under an external electric field of 2.0 kV / mm compared to the shear storage modulus under zero external electric field, and name this value as the relative electrorheological effect. The relative electrorheological effect can be used to evaluate the electrorheological response of the electrorheological elastomer. Figure 9 As can be seen from b, sample ERE-E-5 has the highest relative electrorheological effect, reaching 373.75%, which is more than double that of the other two samples prepared under pre-regulated electric field.

[0096] Example 9: Effect of dispersed phase materials:

[0097] To demonstrate the effectiveness of BTRU in improving the electrorheological properties of ERE-E, silicon dioxide (SiO2, particle size 20 nm) and strontium titanate (SrTiO3, particle size <100 nm), respectively, were selected as the second dispersed phase in addition to TiO2. Electrorheological elastomer samples ERE-A-2 and ERE-B-2 were prepared under a 0.2 kV / mm electric field. SiO2 was the dielectric material with a lower dielectric constant, while SrTiO3 was the dielectric material with a higher dielectric constant. ERE-B-2 was prepared using the exact same procedures as ERE-E-2, except that the BTRU micro-nanoparticles were replaced with an equal mass of SrTiO3 nanoparticles. In the preparation of ERE-A-2, the mass of SiO2 nanoparticles was adjusted to 2.0 g and the mass of silicone oil to 2.9 g to avoid an excessively high dispersed phase volume fraction due to the lower density of SiO2 relative to BTRU. All other procedures were the same as for ERE-E-2.

[0098] The electrorheological properties of ERE-A-2 and ERE-B-2 were tested and compared with ERE-E-2. The results are as follows: Figure 10 .

[0099] from Figure 10 As can be seen, the shear storage modulus of SiO2-modified ERE-A-2 at both zero electric field and 2kV / mm electric field is lower than that of ERE-B-2 and ERE-E-2. Its relative electrorheological effect is also the lowest, at only 7.16%, and it cannot play a role in improving the electrical response. SrTiO3-modified ERE-B-2 has a higher relative electrorheological effect of 99.1%, but its shear storage modulus at zero field is too high, which has an adverse effect on practical applications. ERE-E-2 has the highest relative electrorheological effect of the three elastomers and a moderate shear storage modulus at zero field. This shows that BTRU, as a second dispersed phase in addition to TiO2, can effectively enhance the electrorheological response.

[0100] Example 10: Effect of titanium dioxide particle size and the ratio of two dispersed phases:

[0101] In order to illustrate the rationality of choosing TiO2 with particle size ranging from 100nm to 300nm, the particle size of TiO2 in ERE-E-2 was adjusted to 5-10nm, 10-25nm, 100nm, and 200-400nm respectively. The other steps remained unchanged. Electrorheological elastomers were prepared under 0.2kV / mm electric field and the electrorheological properties were tested. Figure 11As shown in a. When the particle size of TiO2 nanoparticles is too small, the difference between the particle size of TiO2 and BTRU is too large, making it difficult to produce an effective synergistic effect in the process of dual-particle chain formation, thereby enhancing the electrorheological response. When the TiO2 particle size gradually increases to 100-300nm, the relative electrorheological performance of the electrorheological elastomer reaches a higher value. This is because the relatively close but different particle sizes of TiO2 nanoparticles and BTRU micro-nanoparticles are conducive to the complementarity and synergy of chain formation during electric field pre-regulation. When the particle size of TiO2 continues to increase, no significant further improvement in the relative electrorheological effect is found, but instead a downward fluctuation occurs. Therefore, 100nm to 300nm is a more suitable particle size choice.

[0102] In order to find the appropriate ratio of the two dispersed phase micro-nanoparticles, elastomers with TiO2 / BTRU ratios of 1:2, 1:1, and 2:1 were prepared, and the electrorheological properties were tested. The yield rate was calculated based on whether the elastomer could be successfully demoulded and the rheological test could be completed under an electric field of 2 kV / mm. Figure 11 As shown. The 2:1 elastomer has a low BTRU content, and the enhancement of pre-chaining and the improvement of dielectric constant are not obvious, so its relative electrorheological effect is also low. The 1:2 elastomer has the highest relative electrorheological effect, but the increase in BTRU content increases the cost of material preparation, and the yield of the elastomer is low, at 57.1%, which is not conducive to its application. The elastomer with a TiO2 / BTRU ratio of 1:1 has a higher relative electrorheological effect, which can show the improvement of electrorheological response brought about by electric field pre-regulation of dual-particle chaining, and it has a good yield of 85.7%, which is conducive to practical application. From the perspective of comprehensive performance, 1:1 is the appropriate ratio selection for the two dispersed phase micro-nanoparticles.

[0103] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0104] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a high-performance electrorheological elastomer, characterized in that: The continuous phase of the electrorheological elastomer is polydimethylsiloxane, and the dispersed phase of the electrorheological elastomer is titanium dioxide and barium titanyl oxalate wrapped in a urea layer. The mass ratio of the titanium dioxide and barium titanyl oxalate wrapped in the urea layer is 1:

1. After the continuous phase and the dispersed phase are mixed, they are heated in an electric field with an electric field strength of 0.2-0.7 kV / mm to obtain the high-performance electrorheological elastomer.

2. The method for preparing a high-performance electrorheological elastomer according to claim 1, characterized in that: The preparation method of the urea layer-wrapped barium titanyl oxalate comprises the following steps: Step 1-1), 80 g of deionized water was frozen into ice, and 13.4 g of titanium tetrachloride was added to obtain a mixture D; Step 1-2), in a water bath heated at 62°C-64°C, the mixture D was added to 100 mL of a 1.41 mol / L barium chloride solution to obtain a solution E; Step 1-3), in a water bath heated at 62°C-64°C, 100 mL of a 3 mol / L urea solution was added to 300 mL of a 1.4 mol / L oxalic acid solution to obtain solution F; Step 1-4), in a water bath heated at 62°C-64°C, solution E was added to solution F to obtain solution G, and a large amount of ice-water mixture was quickly added; Steps 1-5), rinse solution G with deionized water several times until the pH value exceeds 3; Step 1-6), removing water from the washed solution G, and freeze-drying it at -50°C for 15 hours to obtain the barium titanyl oxalate coated with the urea layer.

3. The method for preparing a high-performance electrorheological elastomer according to claim 1, characterized in that: The titanium dioxide is anatase, and the particle size is 100nm-300nm.

4. The method for preparing a high-performance electrorheological elastomer according to claim 1, characterized in that: The particle size of the barium titanyl oxalate wrapped by the urea layer is 300 nm-5 μm.

5. The method for preparing a high-performance electrorheological elastomer according to claim 1, characterized in that: The curing agent and dimethyl silicone oil are added to the continuous phase, ground and mixed, and then the dispersed phase is added and ground and mixed.

6. The method for preparing a high-performance electrorheological elastomer according to claim 1, characterized in that: The steps include: Step 2-1), add polydimethylsiloxane, curing agent, and dimethyl silicone oil into a grinding device and grind for 5 minutes to fully mix; wherein the mass ratio of polydimethylsiloxane: curing agent: dimethyl silicone oil is 1:0.1:0.923; Step 2-2), titanium dioxide powder and urea-coated barium titanyl oxalate powder were added, and the mixture was ground for 10 minutes to mix thoroughly to obtain a precursor; wherein the mass ratio of the mixture obtained in step 2-1): titanium dioxide powder: urea-coated barium titanyl oxalate powder was 1:0.475:0.475; Step 2-3), pour the ground precursor into the mold, place it in a vacuum drying oven and evacuate to remove bubbles; Step 2-4) Place the mold containing the precursor on the heating table, cover it with a top cover, connect the positive and negative electrodes of a DC high-voltage power supply to the top cover and bottom plate of the mold respectively, place a 200g insulator weight on top of the top cover, turn on the high-voltage power supply switch and apply a voltage of 0.2-0.7kV / mm to form an electric field in the mold; Step 2-5) Turn on the heating table switch and set the temperature to 60°C, heat for 2 hours, turn off the heating table and high-voltage power supply after 2 hours, remove the mold, and place it in a dry place to cool for 15 minutes to cool to room temperature. The material in the mold is the high-performance electrorheological elastomer.

7. The method for preparing a high-performance electrorheological elastomer according to claim 6, characterized in that: The mass fraction of the barium titanyl oxalate wrapped by the titanium dioxide and urea layers in the precursor is 48.72%.

8. The method for preparing a high-performance electrorheological elastomer according to claim 6, characterized in that: The curing agent is a platinum-catalyzed hydrogen-containing siloxane crosslinking agent.

9. The method for preparing a high-performance electrorheological elastomer according to claim 1, characterized in that: The electric field strength is 0.5 kV / mm.

10. Use of the electrorheological elastomer prepared by the method for preparing a high-performance electrorheological elastomer according to any one of claims 1 to 9 in smart materials.

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