Transition from relaxor to ferroelectric-like phase in poly(vinylideneflouride-trifluoroethylene-chloroflouroethylene) terpolymer ultrathin films

Abstract

The poly(vinylidenefluoride-trifluoroethylene-chlorofluoroethylene) terpolymer (56.2/36.3/7.5, mol %) films from 1.6 to 10 nm in thickness were prepared by the Langmuir–Blodgett method. The dielectric and ferroelectric properties of the terpolymer films were investigated. The phase transition of the films of less 3.2 nm in thickness exhibits a ferroelectric-like nature, which is inconsistent with the bulk terpolymers. The peak of the permittivity is at ∼360 K, which is much higher than the thick terpolymer films and it is independent on frequency. Both polarization-electric field and capacitance-voltage curves show a ferroelectric-like characteristic, which is confirmed by piezoresponse force microscopy, suggesting the presence of all-trans molecular conformation.