Preparation and structure of poly(4,4′-oxydiphenylene)pyromellitimide asymmetric ultrafiltration membranes

Abstract

A process was developed for preparing asymmetric ultrafiltration poly(4,4′-oxydiphenylene)pyromel litimide membranes, involving wet forming of the membranes from the prepolymer, followed by catalytic solidphase thermal transformation of the prepolymer into the polyimide. The influence exerted on the structure and characteristics of the membranes by the compositions of the forming solution and precipitation bath, and also by thermal imidization conditions was examined. The optimal conditions were determined for preparing asymmetric ultrafiltration poly(4,4′-oxydiphenylene)pyromellitimide membranes exhibiting the water permeability coefficient of (10−500) × 10−6 m3 m−2 s−1 atm−1 and molecular weight cut-off in the range (5−100) × 103 g mol−1.