Transport properties of aluminophosphate nanocomposite membranes prepared by in situ polymerization

Nanocomposite membranes containing 5 wt% microporous layered aluminophosphate in a polymer matrix were fabricated using in situ polymerization. The gas transport properties of these membranes were evaluated. Polyetherimide was combined with aluminophosphate swelled with several different surfactants. The glass transition temperature of these membranes increased as a result of adding the layered aluminophosphate, however, gas pair selectivity was not improved. A second experiment involved the addition of as-synthesized layered aluminophosphate, which was ball milled to small sizes, to a linear and branched polyimide based on 4,4′-oxydiphthalic anhydride (ODPA), 2,4,6-triaminopyrimidine (TAP), and 4,4′-oxydianiline (ODA) via in situ polymerization. In some cases the gas pair selectivities were improved as a result of adding the layered aluminophosphate. DMTA data suggest no mechanical enhancement with the addition of AlPO, which means that the layers were likely not exfoliated. For this reason, it is most likely that the selectivity enhancements in these samples were not due to molecular sieving through the microstructure of the aluminophosphate.