Abstract
In this work, the poly(vinylidene fluoride)/multi-walled carbon nanotubes (PVDF/MWCNTs) hybrid membranes were obtained through vapor induced phase separation (VIPS). In addition, the effects of solution composition on crystal behavior, elemental composite, morphology and hydrophilicity of membranes surface and the viscosity of casting solution were analyzed. The results of field emission scanning electron microscopy and X-ray photoelectron spectroscopy showed that the rough porous surface could be built in all hybrid membranes due to the slower double diffusion mechanism of the VIPS process, which also provided enough time for MWCNTs to move to the surface and be enriched there, to ensure the lowest surface free energy. Furthermore, other analysis displayed that both adding tiny amounts of MWCNTs and a low concentration of PVDF were favorable to the growth and aggregation of PVDF, which were put down to the adverse effect of hydrophobic MWCNTs on the thermodynamic compatibility of polar casting solution, the less nucleation points and the good fluidity with lower concentration of polymer. Then, the diameter of PVDF spherical particles and the membrane surface roughness increased, whereas the hydrophilicity of membrane surface declined effectively.
Studies on the selective localization of multi-walled carbon nanotubes in blends of poly(vinylidene fluoride) and polycaprolactone
