Surface Modification of Electrospun Poly(vinylidene fluoride) Fibrous Membrane Based on Layer-by-Layer Assembly of TiO ₂ Nanoparticles.

A facile surface modification method of improving hydrophilicity of poly(vinylidene fluoride) (PVDF) membranes was presented by layer-by-layer assembly. Various layers of anatase TiO₂ nanoparticles were successfully deposited on electrospun PVDF fibrous membranes. FTIR, SEM, TEM and droplet scanning analysis were used to investigate microstructure and contact angle (CA) of modified membranes. TiO₂ modified PVDF fibers showed rougher surface and greater diameter compared to uncoated ones. The CA of modified membranes was significantly decreased. For instance, the CA of the 4 layers of TiO₂ modified membranes through two pretreatment methods (viz., ethanol-water displacement or KMnO₄ modification) could be decreased to 0° while the unmodified PVDF had CA of 114.4°. Moreover, the modification through ethanol-water pre-treatment formed TiO₂ coating owing to hydrogen bonds without damaging strength of PVDF. Therefore, this presents a facile and effective hydrophilic modification method for PVDF in water treatment, filtration and other fields.