Hydrophilicity and crystallization behavior of PVDF/PMMA/TiO₂(SiO₂) composites prepared by in situ polymerization

Composites with enhanced hydrophilicity were prepared by adding TiO₂ or SiO₂ nanoparticles during the in situ polymerization of methyl methacrylate (MMA) in poly(vinylidene fluoride) (PVDF). The hydrophilicities of the PVDF/PMMA/TiO₂(SiO₂) composites generated in this manner were characterized by contact angle measurements and atomic force microscopy (AFM). The hydrophilicity was dependent on nanoparticle content; it gradually increased with increasing TiO₂ (or SiO₂) content when the TiO₂ (or SiO₂) content was no more than 4 wt% of PVDF. A homogeneous dispersion of the TiO₂ (or SiO₂) nanoparticles in the composite matrix was observed in scanning electron microscope (SEM) images. Based on Fourier transform infrared (FTIR) spectra and wide angle X-ray diffraction (WAXD) analyses, the crystalline phase composition of PVDF was not influenced by the addition of TiO₂ (or SiO₂); PVDF crystallized predominantly in the α phase after in situ polymerization. Nevertheless, the nanoparticles can promote the formation of the β phase of PVDF in composites; the β-phase content increased with increasing TiO₂ content, while it was almost independent of SiO₂ content.