The morphological changes of expanded polytetrafluoroethylene (ePTFE) membrane caused by solvent soakage were investigated in this study. The results demonstrated that the wettable solvent with low contact angle towards PTFE membrane can introduce huge stress to the ePTFE membrane and make the membrane shrinkage, and the stress is generated in the solvent evaporation procedure. The pore size and membrane dimension shrinkage of ePTFE membrane improved with the decrease of the solvent contact angle and surface tension. For ethanol and isopropanol with contact angle of 23 degrees and 20 degrees, the membrane thickness shrinkness are 15.0% and 16.7%, respectively. The evaporation-induced stress towards the ePTFE membrane also increases with the decrease of the solvent contact angle to the ePTFE membrane. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1464-1468, 2011