(5bh) Nanocomposite Membranes to Purify Gases

As the revolution in nanoscience continues, new materials are discovered with enhanced physical and chemical properties. Concurrently, domestic and international demand for energy requires new technologies for increased fuel productivity, efficiency, and variety. Membranes are at the intersection of these two trends. For years, polymeric membranes have been used to purify natural gas to pipeline specifications. Recently, new domestic energy initiatives have been created to increase H2 and ethanol use as fuels. These initiatives will necessarily require an investigation into the application of current and developing membrane materials as a means to economically and efficiently purify new fuels. Nanomaterials may play an important role in new membrane materials. Exquisite control of nanoscale structural and chemical properties permits rational tailoring of membranes for gas separations. Also, as membranes become increasingly thinner, the understanding of polymer and composite behavior at the nanoscale becomes increasingly critical.

This poster presents an overview of the ability of mineral nanoparticles to alter transport properties of polymeric materials for membrane applications. Nanoparticle filled polymers have been prepared that exhibit over an order of magnitude higher light gas (i.e., carbon dioxide, nitrogen, methane, hydrogen etc.) permeability with little or no change in selectivity relative to that of the unfilled polymer. This phenomena has been observed in a broad range of polymeric materials, from high free volume stiff-chain polyacetylenes and crosslinked poly(ethylene oxide) to commodity materials such as 1,2-polybutadiene and poly(ethylene-co-1-octene). The degree of permeability enhancement is polymer and particle loading dependent, and our studies include a wide range of polymer and particle chemistries, including situations where the polymer and nanoparticles undergo chemical reactions. Moreover, nanocomposite light gas permeability and selectivity are highly dependent on nanoparticle surface chemistry. The nanoparticles are nonporous and are primarily from the metal oxide family (magnesia, silica, titania, etc.). These nanocomposites have been characterized using light gas sorption and permeation to monitor gas transport properties. Particle dispersion in the bulk has been determined using atomic force microscopy.