A computational study of gas molecule transport in a polymer/nanoporous layered silicate nanocomposite membrane material

Polymers containing nanoporous, high-aspect-ratio, inorganic layered materials are being investigated as candidates for overcoming the selectivity versus permeability trade-offs imposed by conventional polymeric membranes used in gas separations. We report the first computational investigation of the transport of gas molecules (in particular helium, hydrogen, nitrogen, and oxygen) in a polydimethylsiloxane/porous layered silicate AMH-3 nanocomposite system as a function of its composition, and also study the effects of polymer-inorganic interactions on the polymer dynamics. The performance of the nanocomposite membrane material is found to be substantially enhanced over the polymeric material for certain separations involving the four molecules studied. The transport properties were found to be strongly influenced by the molecular sieving properties of the AMH-3 layer and the segmental mobility of the polymer in confinement between the inorganic layers. A comparison with the resistances-in-series model for transport through a bulk composite membrane further illustrates the potential for enhanced performance using polymer/porous layer nanocomposite membranes.