Enhanced Gas Permeation through Graphene Nanocomposites

The use of membranes for gas permeation and phase separation offers many distinct advantages over other more energy-dependent processes. The operational efficiencies of these membranes rely heavily on high gas permeability. Here, we report membranes with significantly increased permeability without a considerable decrease in mechanical strength or selectivity, synthesized from a polymer nanocomposite that incorporates graphene and polydimethylsiloxane (PDMS). These graphene–PDMS nanocomposite membranes were able to enhance the gas permeation of N2, CO2, Ar, and CH4 in reference to pristine PDMS membranes. This is achieved by creating interfacial voids between the graphene flakes and polymer chains, which increases the fractional free volume within the nanocomposites, giving rise to an increase in permeation. An optimal loading of graphene was found to be 0.25 wt%, while greater loading created agglomeration of the graphene flakes, hence reducing the effective surface area. We present the enhancements that the membranes can provide to sensing and phase separation applications. We show that these nanocomposites are near transparent to CO2 gas molecules in sensing measurements. This study offers a new area of research for graphene-based nanocomposites.