INVESTIGATION OF THE GAS-TRANSPORT PROPERTIES OF POLYANILINE

Investigations of the rate and selectivity of gas transport in the ele ctronically conductive polymer polyaniline are described. Both rate an d selectivity were found to be dependent on the doping level. Permeabi lity coefficients for all gases studied decreased with increasing dopi ng level, and selectivity coefficients, in general, increased with dop ing level. The effects of other variables, including the nature of the counterion, temperature and duration of thermal processing of the fil m, were also explored. Both free-standing polyaniline films (approxima tely 25-mum thick) and thin film composite membranes based on polyanil ine were studied. The thin film composites were prepared by coating th e polyaniline film (approximately 3-mum thick) onto the surface of a m icroporous alumina support membrane. The free-standing and thin film c omposite membranes showed identical rates and selectivities of gas tra nsport. The highest O2/N2 and CO2/CH4 selectivity coefficients obtaine d were alpha(O2/N2) = 15 and alpha(CO2/CH4) = 55, respectively.