Poly(3-alkylthiophene) membranes for gas separation

The separation of gases is a commercial process conducted primarily via cryogenic distillation. An alternative method involves the use of solvent cast polymer membranes. Unlike distillation, membrane processes are energy efficient, easy to scale-up, and require only electrical energy in their operation. Current membrane separation applications include oxygen or nitrogen enrichment of air, the separation of carbon dioxide from natural gases, and the recovery of hydrogen from refinery and purge streams. In our laboratory, gas separation membranes are being developed based on conducting, soluble and processable polymers such as poly(3-n-alkylthiophene)s. The chemistry of these membranes is being altered by changing the R group (e.g. octyl, dodecyl), the oxidation state, and by incorporating zeolites and molecular sieves to facilitate gas transport. An important aspect of this project concerns establishing the relationship(s) between the structure of poly(3-alkylthiophene) membranes and their bulk properties, specifically permeabilities and selectivities for various gases. It is anticipated that this understanding will help to elucidate the mechanism by which gas separation occurs in these membranes.