Effect of agglomeration of carbon nanotubes on gas permeability of PVTMS/CNT mixed matrix membranes

Mixed matrix membranes (MMMs) with unique transport characteristics can be prepared by the addition of the minor amounts of carbon nanotubes. Qualitative (critical, effective, marked) changes in the membrane performance are shown to be provided by the formation of a percolation cluster composed of nanotubes. For MMMs based on poly(trimethylvinylsilane) (PVTMS) containing carbon nanotubes (CNT), due to the formation of the CNT percolation cluster, gas permeability increases by a factor of 5-15. When the CNT content in the MMMs is higher than the percolation threshold, gas permeability remains on the same level or even decreases. Numerical simulation proves that the above negative changes are provided by the agglomeration of nanotubes and subsequent deterioration of the percolation structure in the membranes. (paper)