The Preparation And Properties Of Dielectric Elastomers Based On Polyacrylate

With the development of robots,automation industry and artificial biological devices,there is an increasing demand for electromechanical conversion devices.The novel high energy-output,high strain,high flexibility,light weight and low cost electromechanical converters will provide strong support for the further development of the industry.As a material for the preparation of mechanical and electrical energy converters,dielectric elastomer(DE)has the advantages of high energy density,large deformation,fast response,high electromechanical conversion efficiency,light weight and low price.However,to achieve good electromechanical conversion performance,it needs a very large driving voltage for the DE materials currently studied,which seriously restricts their application.According to the electromechanical conversion mechanism of the DE,it is known that increasing the dielectric constant and/or reducing the elastic modulus of the DE is a feasible strategy for the DE to achieve large deformation under low driving voltage.With this objective,we have done the following work:(1)The p(BA-AA)copolymer with 69.5 wt%of BA was prepared by ATRP method.The effect of polyethylene glycol 200(PEG 200)on the properties of p(BA-AA)copolymer was investigated.With the addition of PEG 200,the Young’s modulus of p(BA-AA)/PEG 200 blends dramatically decreased,and simultaneously the permittivity increased,and the minimum value of the Young’s modulus is 0.6 MPa,the maximum value of permittivity at 1 kHz is 15.4.The p(BA-AA)/PEG 200 blend achieved an actuation strain of 4.2%at 25 kV/mm.(2)The p(BA-AA)with 78.7 wt%of BA was prepared by ATRP method.The p(BA-AA)/Fe3+ crosslinking polymer was prepared by the complexation of ferric ions with carboxyl groups.The p(BA-AA)/Fe3+ complex displayed>900%of large elongation at break and>2 MPa of high breaking strengthen,and simultaneously the Young’s modulus was relatively small(<1.1 MPa).As the decreasing of Fe3+ content,the dielectric constant of the p(BA-AA)/Fe3+ complexes slightly increased.(3)A series of p(BA-GMA)with different mass fractions of BA were prepared by ATRP method.The self-crosslinking polymer c-p(BA-GMA)were prepared by ring opening reaction of the epoxy groups of GMA.With the decrease of GMA content,the Young’s modulus of c-p(BA-GMA)polymers decreased from 0.41 MPa to 0.11 MPa,and thus the actuation sensitivity dramatically increased from 14.43 MPa-1 to 51.54 MPa-1.The c-p(BA-GMA)achieved high actuation strain of up to 52.1%at a low electric field of 21.6 kV/mm.In addition,the c-p(BA-GMA)-3 was made into a bending actuator,and the actuator exhibited good actuation response.(4)The p(BA-HEA)with 68 wt%of BA was prepared by ATRP method.The polyurethane and acrylate copolymer elastomer,namely p(BA-HEA)@MDI was prepared by the polycondensation of the hydroxyl group(-OH)in p(BA-HEA)with the isocyanate group(-NCO)in MDI.As the amount of MDI decreased,the Young’s modulus of the p(BA-HEA)@MDI significantly decreased.Further,the presence of the urethane groups and-OH groups maintained the dielectric constant of p(BA-HEA)@MDI at a relatively high value of～7.The p(BA-HEA)@MDI-3 achieved a large actuation strain of 14.4%at a relatively low electric field of 15.2 kV/mm.