Phase Transitions and Ferroelectric Relaxor Behavior in P(VDF−TrFE−CFE) Terpolymers

We show that the microstructures and phase transition behavior of vinylidene fluoride−trifluoroethylene−chlorofluoroethylene terpolymer, P(VDF−TrFE−CFE), with composition of 61.5/30.3/8.2 mol %, can be varied dramatically via different processing conditions. In the well-annealed sample, the polymer exhibits typical relaxor ferroelectric behavior with the nonpolar crystalline phase having a chain structure of random sequence of TT/TG/TG‘ conformations. In contrast, by lowering the crystallization temperature in the solution-cast films, the polar crystal phase with all-trans (Tm>4) planar zigzag conformation (similar to the ferroelectric phase in the corresponding copolymer) can appear or even become a dominating phase. Four types of transitions can be detected in this terpolymer, besides the crystal melting, the glass transition in amorphous region, and the transition between the ferroelectric-like and paraelectric crystals (30−90 °C), an additional transition appears near 10 °C which can be attributed to ...