Infrared spectroscopic studies on crystalline phase transition of PVDF and PVDF/hyperbranched polyester blend ultrathin films

Crystalline phase transition behavior in PVDF/hyperbranched polyester (HBP) blend ultrathin film samples subjected to heating-cooling (30 → 210 (>Tm) → 30 °C) cycle were studied using in-situ FTIR-TS and FTIR-GIRAS techniques as a function of as-cast (AC) and annealed at 130 °C (AN) conditions. Ferroelectric crystalline phase is enhanced by the addition of HBP (10 wt.-%) in PVDF. Additionally, the PVDF/HBP blend sample exhibited reversible thermal hysteresis. For neat PVDF, ferroelectric crystalline content is drastically reduced due to the unfavorable changes in chain and dipole orientations upon heating and cooling. Overall, the PVDF/HBP (AN) sample is suitable for fabricating non-volatile random access memory devices due to their memory effect even after completing a heating-cooling cycle.