Miscibility, crystallization and annealing studies of poly(vinylidene fluoride)/hyperbranched polyester blends

In this study, miscibility and crystallization behavior of polyvinylidene fluoride (PVDF) and its blends with hyperbranched polyester (HBPE, 0 to 50 wt.-% of HBPE in PVDF) are investigated by means of DSC and FTIR techniques. Among the varying blend compositions, PVDF/HBPE (100/0 and 90/10) blend ultrathin film samples were subjected to thermal annealing at different temperatures (30-200 °C) in order to examine and compare their crystallization behavior. From FTIR data, the all-trans band (A1) at ca. 1280 cm−1 corresponding to the changes in ferroelectric β-crystalline phase for both the samples exhibits higher absorption intensity upon annealing at 90 °C, well below their melting temperature range (Tm∼160 °C), whereas, the sample melt-annealed at 210 °C exhibit reduced A1 absorption intensity, which is attributed to the crystalline transformation from ordered ferroelectric phase into the disordered amorphous phase. Quantitative data from Factor analysis revealed the existence of higher ferroelectric β-crystalline phase content in PVDF/HBPE (90/10) blend ultrathin film sample than in commercially available PVDF and PVDF/TrFE (72/28) ultrathin film samples, which exemplifies the importance of this study. The enhanced ferroelectric characteristics exhibited by the PVDF/HBPE (90/10) blend ultrathin film samples can be well-suited for electronic applications such as non-volatile memory devices, sensors, etc.