The syntheses of oligodimethylsiloxane film forming materials and their organoselective properties for the removal of ethanol and phenol from water by pervaporation are reported. Two series of segmented polydimethylsiloxane-imide (PSI) copolymers were synthesized from alpha,omega-(bisaminopropyl) dimethylsiloxane oligomers (ODMS) and aromatic dianhydrides (PMDA, 6FDA); synthesized PSI were obtained with a high content of siloxane block, i.e. up to 94 wt.%. To improve the average molecular weight of siloxane copolymers prepared from the longer chain length ODMS, the particular extender 1,3-bis(3-aminopropyl) tetramethyldisolxane (MDMS) was used, giving thus materials with enhanced mechanical properties. Pervaporation (PV) results showed that the PSI led to a selective recovery of the organic compounds from their aqueous mixtures. The structure-properties relationships of these materials are discussed with respect of polydimethylsiloxane-imide microstructures, taking into account especially the dianhydride type and the chain length of the oligomers used. PSI having a high amount of siloxane blocks gave the best PV results and optimum pervaporation performances were obtained with membranes incorporating aromatic fluorinated residues (feed = 5 wt.% PhOH: alpha = 22 and J(10mum) = 2.4 kg/m(2) h/feed = 10 wt.% EtOH: alpha = 10.6 and J(10mum) = 0.56 kg/m(2) h). (C) 2004 Elsevier B.V. All rights reserved.