Advances in the design of co-poly(ether-imide) membranes for CO2 separations. Influence of aromatic rigidity on crystallinity, phase segregation and gas transport

Abstract In our previous works, it was observed a clear relationship between the structure and the properties for different copoly(ether-imide)s, besides a good relation was found between SAXS characterization and permeability results. Here, a series of aliphatic aromatic copoly(ether-imide)s, based on an aromatic diamine (ODA), a diamine terminated poly(ethylene oxide) (PEO2000) of a molecular weight of 2000 g/mol and different aromatic dianhydrides (BPDA, BKDA (or BTDA) and PMDA) has been synthesized and characterized. The permeability for O 2 , N 2 , CO 2 and CH 4 , increased with the rigidity of the monomers (BKDA  Attending to glass transition temperature, T g , of the aliphatic part, to its melting temperature, T m , and to its crystallinity, segregation was better for more rigid dianhydrides at lower temperatures of treatment. Higher dianhydride rigidity produced better mechanical properties that were good but decreased a little bit when the percentage of PEO in the samples increased. Good permselectivity compromises were attained for the CO 2 /N 2 separation. This work gives indications on how to design advanced materials for this separation with the increasing possibilities of controlled structure and properties.