Highly electrostrictive poly(vinylidene fluoride-trifluoroethylene) networks

We report greatly improved electromechanical performance from a poly(vinyli dene fluoride-trifluoroethylene) copolymer by chemical cross linking. Curin g with an organic peroxide in combination with a free-radical trap, followe d by crystallization, yields a ferroelectric network exhibiting a high elec trostrictive response. The electric-field-induced strains were measured at low frequency using an air gap capacitance method and by a noninterferometr ic optical technique. At electric fields as low as 9 MV/m, longitudinal str ains 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 fluoropolyme r. Since the mechanical modulus of the network is high (similar to0.5 GPa), this work demonstrates the potential for extending the range of utility fo r polymer-based electromechanical materials. (C) 2001 American Institute of Physics.