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 a phase after in situ polymerization. Nevertheless, the nanoparticles can promote the formation of the beta phase of PVDF in composites; the beta-phase content increased with increasing TiO2 content, while it was almost independent of SiO2 content.