<i>β</i> phase instability in poly(vinylidene fluoride/trifluoroethylene) thin films near <i>β</i> relaxation temperature

Abstract

The β phase stability in poly(vinylidene fluoride/trifluoroethylene) [P(VDF-TrFE)] thin films was studied below 300 K using X-ray diffraction and polarization-electric-field (P-E) hysteresis loops measurements. On as-grown samples, an irreversible partial order-disorder transformation at Tβ ∼ 250 K, namely, the β relaxation temperature, was evidenced by the appearance of an additional X-Ray diffraction peak above Tβ as well as changes on the P-E loops on heating after the first cooling. This order-disorder-like transformation which is attributed to an all-trans order to helical disorder transition is suggested to take place in defect-rich regions like crystal-amorphous interphases and/or crystalline areas with randomly distributed TrFE defect-like units.