The Beneficial Impacts of Functional Groups of CNT on Structure and Gas Separation Properties of PEBA Mixed Matrix Membranes

Incompatibility between filler and polymer chains accompanied by particle agglomeration has a detrimental effect on the performance of mixed matrix membranes (MMMs). To obviate intermolecular forces of different additives, functional groups (-COOH, -NCO, and -NH2) were grafted on the surface of multi-walled carbon nanotubes (MWCNTs) which were then incorporated as fillers in the poly(ether-block-amide) (PEBA) polymeric matrix in the range of 0.1-1 wt% loading. CO2 permeability and ideal CO2/N-2 and CO2/CH4 selectivity of MMMs was compared with the neat membrane, and the results revealed favorable enhancement and surpassed CO2/N-2 Robeson's upper bound under 4-10 bar in the range of 15-55 degrees C. Mixed gas separation performance of MMMs, which is of vital importance in industrial applications, was also investigated. The results indicate that MWCNT-NCO created superior grafts with the polymer chains, and MMMs with this additive had a better gas separation performance with high mechanical and thermal stability.