Facile Fabrication of Highly Oriented Ultrathin Poly(vinylidene fluoride) Films with High Polar Phase Content

Highly oriented ultrathin films of poly(vinylidene fluoride) (PVDF) and its blends with cetyltrimethylammonium bromide (CTAB) are prepared by the melt-draw technique. The effects of CTAB and melt-draw conditions on the structure and morphology of the melt-drawn PVDF ultrathin films are explored in detail by different techniques. It is found that the polar phase content, crystallinity, and orientation of the melt-drawn PVDF films are effectively enhanced by the introduction of CTAB, which is attributed to the synergistic effect of ion–dipole interaction and longitudinal flow field caused by melt-draw. A high polar phase content of 84.32% is achieved in the blend with 5 wt % CTAB, which is approximately 4.5-fold that in pure PVDF melt-drawn films. This is of great importance in fabricating highly oriented PVDF ultrathin films with a high polar phase content and high crystallinity for advanced applications.