Ion-Stabilized Membranes for Demanding Environments Fabricated from Polybenzimidazole and Its Blends with Polymers of Intrinsic Microporosity

Abstract

Robust, ion-stabilized membranes from polybenzimidazole (PBI) and its blends with polymer of intrinsic microporosity (PIM-1) were fabricated for organic solvent nanofiltration in polar aprotic solvents (PAS). Flat sheet membranes comprised of polybenzimidazole and 4–12 wt % PIM-1 were fabricated via conventional phase inversion followed by the reduction of nitrile PIM-1 to amine PIM-1. Stabilization of the membranes was achieved via ion formation (chloride salt) under acidic conditions. Such simple ion-stabilization methodology could replace cumbersome cross-linking. The aging of the membranes and the their performance at room and elevated temperatures, in a wide range of pH, in the presence of organic bases, in six conventional and two green PAS, were investigated. The PIM-1 content enabled fine-tuning of the molecular weight cutoff (MWCO) of the membranes between 190 and 650 g mol–1.