Cross-linked polyimide membranes for solvent resistant nanofiltration in aprotic solvents

Solvent stable nanofiltration membranes were prepared through the chemical cross-linking of asymmetric Matrimid (R)-based polyimide membranes with p-xylylenediamine. The influence of this straightforward post-treatment on membrane stability, morphology and performance in dimethylformamide (DMF), N-methylpyrrolidinone (NMP), dimethylacetamide (DMAc) and dimethylsulfoxide (DMSO) was thoroughly investigated. With permeabilities up to 5.4 l/m(2) bar h and rejections up to 98% for low molecular weight dyes in these demanding solvents, optimally performing, truly solvent resistant nanofiltration membranes were obtained. Nanozeolite-filled membranes were prepared in parallel to study the effect of an inorganic filler on the cross-linking reaction and performance in aprotic solvents. The outstanding stability and performance of these membranes and their easy preparation clearly offer vast potential for applications in harsh solvent environments. (c) 2008 Elsevier B.V. All rights reserved.