AbstractHydroxyterminated polybutadiene (HTPB)‐based polyurethaneurea (PU), HTPB‐PU, was synthesized by two‐step polymerization and was firstly used as membrane materials to recover aroma, ethyl acetate (EA), from aqueous solution by pervaporation (PV). The effects of the number–average molecular weight (Mn) of HTPB, EA in feed, operating temperature, and membrane thickness on the PV performance of HTPB‐PU membranes were investigated. The membranes demonstrated high EA permselectivity as well as high EA flux. The DSC result showed two transition temperatures in the HTPB‐PU membrane and contact angle measurements revealed the difference of hydrophobicity of the membrane at both sides, which were induced by glass plate and air, respectively, due to movement of the soft hydrophobic polybutadiene (PB) segments in HTPB‐PU chains. Furthermore, the PV performance of the HTPB‐PU membrane with the hydrophobic surface facing the feed was much better than that with the hydrophilic surface. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 552–559, 2007