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 (T_m∼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.