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

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.