Influence of Hot‐Press Temperature on β‐Phase Formation and Electrical Properties of Solvent‐Casted PVDF‐HFP Co‐Polymer Films Prepared from Two Different Solvents: A Comparison Study

Poly(vinylidene fluoride)‐ co ‐hexafluoropropylene (PVDF‐HFP) co‐polymer films are prepared via solution casting followed by hot‐press method. Two different types of solvents, viz., solvent mixture DMF and acetone and single solvent only DMF are used to prepare two sets of samples which are then hot‐pressed at various temperatures (110, 120, and 130 °C) to study the effect of hot‐press temperature on samples prepared from different types of solvents. X‐ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra shows formation of electroactive β‐phase whose fraction remaining above 71% for all the synthesized samples. Differential scanning calorimetry (DSC) is performed to obtain the degree of crystallinity of the as‐prepared samples and the hot‐pressed samples seemed to have a single exothermic melting peak instead of two in case of the casted ones. Dielectric properties and AC conductivity of the samples are also studied. The highest dielectric constant among the synthesized samples is found to be ≈12 at 1 kHz at room temperature. The static hysteresis loops are traced for all the as‐synthesized films. Remnant polarization is found to increase with increase in the hot‐press temperature, the coercive field remaining almost similar for all of them. The PUND analysis is also carried out for the all as‐prepared samples. A comparison study is presented through this report, emphasizing the influence of hot‐press temperature on β‐phase fraction of PVDF‐HFP films prepared from two different types of solvents, intended for energy harvesting and storage applications.