There is a need for new low energy CO2 capture technologies. At present, CO2 is removed from gas mixtures by adsorption technology, e.g. amine scrubbing or low temperature condensation methods. Membrane technology has proven to be an energy efficient technology towards the separation of CO2 from natural gas in industrial applications. For membrane materials, glassy polymers have been investigated as they have a rigid structure and they typically exhibit high selectivities. On the downside, however, they often suffer from CO2-induced plasticization, which results in a significant drop in selectivity. Poly(etherimide)s (PEIs) are very attractive materials for gas separation applications as they display high selectivities for gas pairs such as CO2/CH4 and PEIs exhibit excellent physical and thermo-mechanical properties, such as high glass-transition temperatures (Tg), thermal stability, high chemical resistance, and mechanical strength. [1,2]
Our current research line has a strong focus on high-performance polymer architectures based on polyetherimide (PEI) chemistries as potential materials for high-pressure gas separation applications. In this project new monomers and polymers will be designed and synthesized, and their thermo-mechanical properties characterized. We are in the process of preparing a homologous series of PEI films with only subtle backbone modifications, e.g. ortho-, meta-, and para-modifications of the diamine moiety, and their usefulness as films for a variety of gas separation applications (e.g. separation of high-pressure CO2/CH4) will be investigated (Figure 1). With this systematic approach we hope to elucidate the complex interplay between polymer backbone chemistry, chain packing and polymer–CO2 interactions. Our initial results have demonstrated that PEI films with an ODPA dianhydride moiety (ODPA-P1) display high selectivities in experiments at elevated pressures with a 50/50% CO2/CH4 feed gas mixture over other dianhydride moieties. In summary, this project focuses on structural alterations of all-aromatic poly(etherimide)s and the effects on chain packing and CO2 affinity. Our ultimate aim is to provide a new generation polymeric membranes for high-pressure CO2/CH4 gas separation without loss of permeability and selectivity.
Figure 1: Polyetherimide target structures based on different dianhydride and diamine moieties
 Cecopierigomez, M. et al. On the limits of gas separation in CO2/CH4, N2/CH4 and CO2/N2 binary mixtures using polyimide membranes. Journal of Membrane Science 293, 53-65 (2007).
 Xiao, Y.T. et al. The strategies of molecular architecture and modification of polyimide-based membranes for CO2 removal from natural gas — A review. Progress in Polymer Science 34, 561-580 (2009).
 Simons, K. et al. CO2 sorption and transport behavior of ODPA-based polyetherimide polymer films. Polymer 51, 3907-3917 (2010).