Improvement in the permeation performance of hybrid membranes by the incorporation of functional multi-walled carbon nanotubes

The morphology and swelling performance of poly(methyl methacrylate) (PMMA) and polyurethane (PU) membranes containing pristine multi-walled carbon nanotubes (P-MWCNTs) was investigated. Next, amino (NH2) groups were introduced into the MWCNTs by chemical modification for improving their affinity to the membranes, thereby resulting in a better distribution of the MWCNTs in the membranes. The performance of the hybrid membranes was evaluated by swelling and pervaporation experiments. The Fourier transform infrared and transmission electron microscopy analyses showed that the addition of both the pristine and functionalized MWCNTs to the membranes improved their permeation performance. The dispersion of the P-MWCNTs and MWCNTs-NH2 in the PU hybrid membranes was better than that in the corresponding PMMA hybrid membranes because of the rapid polymerization rate of the monomers and the elasticity of the membranes. Thus, the P-MWCNTs/PU and MWCNTs-NH2/PU hybrid membranes performed better than the corresponding P-MWCNTs/PMMA and MWCNTS-NH2/PMMA hybrid membranes. The surface functionalization promoted the affinity of the MWCNTs to the monomer solution and the polymer membranes. Compared to the P-MWCNTs, the MWCNTs-NH2 showed an improved distribution in the PU and PMMA hybrid membranes, and the membranes containing the MWCNTs-NH2 performed better than those containing the P-MWCNTs.