Significantly enhanced electromechanical performance of PDMS crosslinked PVDF hybrids

Poly(vinylidene fluoride)-based ferroelectric polymers have large and tunable dielectric permittivity (ε_r), but rather high Young's modulus (Y), which limits its electromechanical response when used as actuators. In this work, a silicone oligomer involving amino groups is employed to crosslink a non-crystallized poly(vinylidene fluoride-chlorotrifluoroethylene) matrix bearing double bonds (P(VDF-CTFE-DB)) via addition reaction. Thanks to the flexible silicone molecules, the modulus of the hybrids is reduced over 30% when compared with the pristine matrix. Most interestingly, the ε_r of the hybrids is improved to nearly 100% higher than that of the matrix when the silicone content reaches 30 wt %. This may be due to the dilution effect of silicone molecules, which favors macromolecular chain rearrangement and dipole orientation of the hybrids under an applied electric field. As a result, electric-field activated displacements of the above hybrid increases to 0.73 mm from 0.48 mm of the matrix under 60 MV/m. The maximum electric field-induced thickness strain increases from 1% of the matrix to nearly 3% of the crosslinked hybrid. This work may provide a facile strategy to fabricate PVDF-based hybrids with enhanced electromechanical performance under low activating voltage.