Highly electrostrictive poly(vinylidene fluoride–trifluoroethylene) networks

We report greatly improved electromechanical performance from a poly(vinylidene fluoride–trifluoroethylene) copolymer by chemical cross linking. Curing with an organic peroxide in combination with a free-radical trap, followed by crystallization, yields a ferroelectric network exhibiting a high electrostrictive response. The electric-field-induced strains were measured at low frequency using an air gap capacitance method and by a noninterferometric optical technique. At electric fields as low as 9 MV/m, longitudinal strains of 12% are obtained. This is more than two orders of magnitude better than conventional vinylidene fluoride materials, and more than an order of magnitude larger than the best results reported to date on any fluoropolymer. Since the mechanical modulus of the network is high (∼0.5 GPa), this work demonstrates the potential for extending the range of utility for polymer-based electromechanical materials.