A novel surface modification technique for polyimide membranes their characterization and organic solvent filtration performance is described. The resultant brush layer and polyimide support are characterized and tested for organic solvent filtration. The process involves treating crosslinked polyimide membranes with surface initiators followed by Single Electron Transfer- Living Radical polymerization (SET-LRP) with alkyl methacrylates. Proof of grafting is established using ATR-FTIR, XPS and FESEM. The degree of grafting and brush height and hence selectivity and permeability are found to be a function of monomer type and polymerization time. The filtration performance of these composite membranes was measured using the permeability of 10 organic solvents and the selectivity and fouling of an organic dye (Rose Bengal) in ethanol. These studies provide a basis for designing polymeric membranes comprising brush selective layers with defined microstructure not possible with the widely popular phase inversion process.
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