Highly stable “pore-filling” tubular composite membrane by self-crosslinkable hyperbranched polymers for toluene/n-heptane separation

Abstract

The stability of membrane is a key issue for pervaporation separation of aromatic/aliphatic hydrocarbon mixtures. In this study, in order to enhance the stability, composite membrane with “pore-filling” structure was formed on porous ceramic tubular substrate. A simple self-crosslinking strategy based on the unique hyperbranched macromolecule, Boltorn W3000, was utilized in the preparation procedure. The hydroxyl and carboxyl groups on Boltorn W3000 molecules reacted at intramolecular and intermolecular during thermal cross-linking process, and then hyperbranched polymers were assembled onto the top layer and sublayer of the ceramic substrate. The morphologies and structures of “pore-filling” composite membrane were characterized by FTIR, SEM, and Nano Indenter. Moreover, “non-pore-filling” membrane was also prepared by the same method with an additional “plugging-holes” step. Both of these two composite membranes were used for separating toluene/n-heptane mixtures. The results indicated that the “pore-filling” membrane showed more stable separation performance, due to its excellent anti-swelling properties. This work thus not only illustrated a new approach for the preparation of “pore-filling” membrane, but also produced a potentially useful organic/inorganic composite membrane for aromatic/aliphatic hydrocarbon mixtures separation.