Pushing the limits of polymeric membrane technology to supercritical carbon dioxide (scCO₂) separations is of particular interest for fluoropolymer synthesis. Developing a robust membrane that can withstand the plasticization effect of such high pressure CO₂ is a key challenge. Plasticization results in increased segmental mobility of the polymeric chains and thus reduces its separation capacity.

We have chosen Torlon®, a polyimide-amide polymer, as the polymeric material of choice for this separation. It is believed that the polyimide-amide forms intra/inter chain hydrogen bonding which can provide resistance to plasticization. We further aim to decrease the plasticization by incorporating molecular sieves in the polymer matrix. In the case of enhanced polymer zeolite interactions, it is believed that the chains near the sieve interface become rigidified and thereby provide resistance to plasticization.

A defect free asymmetric hollow fiber membrane has been successfully formed from Torlon® using a dry-wet spinning process. This defect free membrane provides stable selective separations up to 1100psi of CO₂. Details of the separation performance will be disclosed. Preliminary studies in making a composite membrane with a good polymer zeolite interaction will also be presented.