Direct Preparation of Nanoscale Thin Films of Poly(vinylidene fluoride) Containing β-Crystalline Phase by Heat-Controlled Spin Coating

Nanoscale thin films of PVDF containing the beta-crystalline phase were directly prepared by heat-controlled spin coating without the influence of external stimuli either in the form of additives or post-treatments. Sample preparation was carried out at different temperatures, ranging from 10 to 70 degrees C. At elevated temperatures (40, 50, 60 and 70 degrees C), PVDF was crystallized into the beta-phase, while at near-ambient conditions (20 and 30 degrees C) it was crystallized into the beta-phase. Some samples exhibited a phase-segregated morphology, with varying particle sizes depending on the preparation temperature. The ferroelectric nature of a typical sample, prepared at 40 degrees C, was visualized by piezoresponse imaging studies.