Effect of crystal structure on nanofiber morphology and chemical modification; design of CeO2/PVDF membrane

Abstract

Layered crystal structures tend to form flat platelet-like crystallites, and nanofibers having such a structure exhibit strip-like morphology. Crystallographic plane forming the dominant flat surface of the nanofibers can be used for surface modification with catalytically active nanoparticles capable of anchoring to the dominant flat surface. In this study, polyvinylidene fluoride (PVDF) nanofibers exhibiting strip-like morphology and longitudinal folding were prepared using wire electrospinning, and surface modified with CeO2 nanoparticles. Experimental characterization of the CeO2/PVDF membrane using (high-resolution) scanning electron microscopy and X-ray photoelectron spectroscopy was supplemented by a force field-based molecular modeling. The modeling has shown that the dominant PVDF(100) plane is suitable for anchoring the CeO2 nanoparticles. In this respect, the PVDF(100) plane is comparable to the less exposed fluorine-oriented PVDF(010) plane, and both planes show stronger interaction with CeO2 compared to hydrogen-oriented PVDF(010) plane. Molecular modeling also revealed preferred crystallographic orientations of anchored CeO2 nanoparticles: these are the catalytically active planes (100), (110), and (111). The successful surface modification and the finding that CeO2 nanoparticles on the dominant PVDF(100) surface can preferentially exhibit these crystallographic orientations thus provides the possibility of various practical applications of the CeO2/PVDF membrane.