| Dielectric elastomer(DE),as an electroactive polymer,can convert electrical energy into mechanical energy under the action of an electric field.Because of its advantages of light weight,high electro-deformation,high energy density,and high energy conversion rate,it has wide application prospects in micro robots and other fields.To obtain high electro-deformation in DE materials,a high driving voltage is required,which limits the development of DE.Therefore,how to obtain large deformations at low voltage is a key issue that needs to be solved urgently in the research of DE materials.According to the driving strain mechanism of DE,under the premise of the same electric field strength,increasing the dielectric constant of the material and reducing the modulus is the key to improving the electrical deformation of the material.In response to this goal,we synthesized a carboxyl silica gel(PMVS-COOH)with a large number of carboxyl groups and an epoxy acrylate rubber(BA-GMA)with epoxy groups,which were separately combined with polyurethane(TPU)Blended to increase the dielectric constant and reduce the elastic modulus at the same time,by controlling its blending ratio to adjust its internal phase structure,a series of dielectric elastomers with high electromechanical sensitivity factors and high electro-deformation at low voltage were prepared material.We first synthesized and optimized carboxyl silica gel with a carboxyl content of 100%,and blended it with TPU to prepare TPU/PMVS-COOH DE material.By controlling the blending ratio of PMVS-COOH and TPU to adjust the internal phase structure of the blended material,it was found that when the PMVS-COOH content is 30%,the phase interface formed by PMVS-COOH and TPU is the most,and the interface polarization ability is the strongest At the same time,a large number of carboxyl groups contained in PMVS-COOH break the hydrogen bond in the TPU,which significantly improves the dipolar polarization ability of DE.Therefore,the DE blend with a PMVS-COOH content of 30%has the highest dielectric constant.In addition,because the elastic modulus of PMVS-COOH itself is very low,the elastic modulus of the resulting blend is significantly lower than that of pure TPU,so that the electromechanical sensitivity factor of the blend material is increased by 3.6 times,and the maximum electro-deformation is increased by 4.26 Times.In future work,the elongation at break and tensile strength of the resulting TPU/PMVS-COOH DE blend need to be further improved.On the other hand,an epoxy acrylate rubber with epoxy groups was synthesized by atom transfer radical polymerization(ATRP)and blended with TPU to prepare TPU/BA-GMA DE material,in which the ring The oxygen group serves as a crosslinking point to crosslink BA-GMA.The results showed that the large number of carbonyl groups contained in BA-GMA destroyed the hydrogen bonds in the TPU matrix,and significantly improved the dipolar polarization ability of the DE blend.In addition,BA-GMA and TPU form many phase interfaces,which significantly improves the interface polarization ability of the DE blend.The simultaneous increase of these two polarization capabilities makes the dielectric constant of the blend significantly increase.When the content of BA-GMA is At 40%,the dielectric constant of the DE blend reaches the highest.Because the elastic modulus of BA-GMA itself is very low,its introduction significantly reduces the elastic modulus of TPU,and adjusts the phase structure by controlling the blending ratio of BA-GMA and TPU.When the BA-GMA content is 40%,the nanophase interface is formed inside the material.At this time,the compatibility is the best,the elastic modulus is only 1MPa,which is much lower than the 5.2MPa of TPU.The electric field strength of the blended material is At 13.3kV/mm,the maximum electro-induced deformation reached 7.41%,achieving the goal of larger deformation at a lower voltage.At the same time,it also has a higher elongation at break than TPU and can guarantee a certain tensile strength. |
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