In this study, the effects of solvent and magnesium chloride hexahydrate (MgCl2 center dot 6H(2)O) on the polymorphism of polyvinylidene fluoride (PVDF) thin films were systematically investigated. Wherein, N,N-dimethylformamide (DMF) and water with different volume ratio were used as mixed solvents to obtain the solution casting films, P series. In addition, MgCl2 center dot 6H(2)O was comparatively added to prepare PVDF/MgCl2 center dot 6H(2)O hybrid films, P-M series. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and differential scanning calorimeter (DSC) were utilized to study the influence of the water content in the mixed solvents and the hydrated salt on crystallization behavior of PVDF. Further, the morphologic images from scanning electronic microscopy (SEM) and polarized optical microscopy (POM), as well as the pizoelectirc d(33) test also supplies the corresponding evidences. As indicated, the water in the mixed solvent shows different effect on main crystal forms of PVDF. At low water content, the solvents may favor the polar phase (beta- and gamma-phase) mainly by hydrogen bonds interactions between PVDF and water, together with dipolar interactions between PVDF and DMF. At high water content, the nonsolvent water will impose confinement effect on polymer chain diffusion and crystal growth which facilitate the formation of alpha-phase PVDF. Moreover, magnesium chloride hexahydrate mainly functioned as the nucleation sites for PVDF crystallization. The result of small-angle X-ray scattering (SAXS) implies the content of water or MgCl2 center dot 6H(2)O has little impact on the structure of the long period. (c) 2013 Elsevier Inc. All rights reserved.