Electroactive polymers with high dielectric constant (K) can generate a large strain response under an electric field and they are promising candidate materials for artificial muscles. By introducing carefully controlled defects, normal ferroelectric polymer poly (vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] can be converted into a relaxor ferroelectric material with electrostrictive strain up to 7% and room temperature dielectric constant above 50. These defects can be created by either high-energy electron irradiation or copolymerization with a third bulky comonomer chlorofluoroethylene. Furthermore, giant K can be achieved in all-polymer percolative composites with organic semiconductor copper-phthalocyanine or conducting polymer as the filler. The recently developed nano-composites have K up to 1000 and electromechanical strain above 10%.
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