Polar phase formation in poly(vinylidene fluoride) induced by melt annealing

It is still a challenge to obtain polar phase of poly(vinylidene fluoride) from melt crystallization at normal conditions. This study demonstrates that polar beta- and ? phases can be produced through melting re-crystallization of a phase, provided that moderate memory effects in the melt is achieved by annealing. Otherwise, it is inevitable to re-crystallize into a phase without any trace of polar phase. Small fragments, generated from the disintegration of long TGTG' sequences, most likely adopt trans conformation in the melt before approaching random coils, thus responsible for the formation of polar phase upon cooling. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012