NSF Award
9661545
*** 9661545 Pinnau This project addresses the development of a new class of gas separation membranes based on superglassy polymers. Superglassy polymers are characterized by high glass transition temperatures, high free volume, large intermolecular chain spacing, connectivity of free volume elements, extremely high hydrocarbon permeability and high hydrocarbon/permanent-gas selectivity. it was recently discovered that poly(1-trimethylsilyl-1-propyne) PTMSP , the only superglassy polymer studied to date, can show a mixed-gas selectivity of 30 for e-butane over methane, the highest selectivity ever observed for this important mixture. However, the potential use of PTMSP membranes is limited because its chemical resistance to higher hydrocarbons and aromatic hydrocarbons is poor. The project goal is to develop novel, chemically resistant superglassy polymer membranes based on disubstituted polyacetylenes. Preliminary pure-gas permeation studies with one such polymer show that its permeability and selectivity for the e-butane/methane mixtures separation are lower than those of PTMSP, but high enough to be promising. Unlike PTMSP, the polymer is completely stable in an aliphatic and aromatic hydrocarbon environment. It is believed that the permeability and selectivity of the polymer can be increased by proper structural modifications. Membranes make from superglassy polymers could have a significant impact on many important industrial vapor separations. Possible applications include recovery of C3+ hydrocarbons from hydrogen in the petrochemical industry. The superior selectivity and permeability of superglassy polymers relative to state-of-the-art rubbery membranes should make membrane systems competitive with conventional separation methods such as cryogenic separation in these or other applications. ***
