Morphology, crystalline structure, and properties of poly(vinylidene fluoride)/silica hybrid composites

Poly(vinylidene fluoride)/silica (PVDF/SiO2) hybrid composite films were prepared via sol-gel reactions from mixtures of PVDF and tetraethoxysilane in dimethylacetamide. Their morphology, crystalline structure, and thermal, mechanical, and electrical properties were examined. For morphology measurements, scanning electron microscopy and optical microscopy were applied. X-ray diffraction and infrared analyses showed that the crystalline structure of PVDF was not changed much by the addition of SiO2, indicating that there was no interaction between PVDF and SiO2. With increasing SiO2 content, the melting temperature rarely changed, the degree of crystallinity and the dielectric constant decreased, and the decomposition temperature slightly increased. A PVDF/SiO2 hybrid composite film with 5 wt % SiO2 exhibited balanced mechanical properties without a severe change in the crystalline structure of PVDF, whereas for the hybrid composites with higher SiO2 contents (> 10 wt %), the mechanical properties were reduced, and the spherulite texture of PVDF was significantly disrupted by the presence of SiO2 particles. (C) 2001 John Wiley & Sons, Inc.