Effect of functionalized multi-walled carbon nanotubes on the microstructure and performances of PVDF membranes

Functionalized multi-walled carbon nanotubes (f-MWCNTs) were synthesized by grafting carboxyl groups and 3-aminopropyltriethoxysilane (APTS) on the nanotube surface, respectively. A novel polyvinylidene fluoride (PVDF) membrane was prepared by incorporation of different dosages of APTS modified MWCNTs (A-MWCNTs) via the phase-inversion method. The dispersity of MWCNTs and compatibility between MWCNTs and the polymer matrix were enhanced after functional modification. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) testing showed that A-MWCNTs/PVDF blend membranes exhibited superior surface morphology and pore structure. Because of a strong interfacial interaction with the PVDF matrix, the mechanical strength of PVDF membranes was improved by adding A-MWCNTs and the optimum addition content was 2 wt%. More importantly, the bovine serum albumin (BSA) rejection of membranes increased significantly from 64.2% (nascent PVDF membranes) to 92.48% (A-MWCNTs/PVDF), which was attributed to the network structure of APTS. It can be expected that the blending modification of PVDF membranes by f-MWCNTs will have a bright and foreseeable application prospect.