Surface-modification of poly(dimethylsiloxane) membrane with self-assembled monolayers for alcohol permselective pervaporation.

The use of self-assembled monolayers (SAMs) has recently been recognized as an effective way to tailor the surface properties of films used in various applications. However, application of SAMs in the preparation of separation membranes remains unexplored. In the present study, surface-modified poly(dimethylsiloxane) (PDMS) membranes were prepared using SAMs to fabricate a membrane for use in pervaporation separation of ethanol/water mixtures. A cross-linked PDMS/polysulfone (PSf) composite membrane was transformed by introducing hydroxyl functionalities on the PDMS surface through a UV/ozone conversion process. (Tridecafluoroctyl)triethoxysilane was allowed to be adsorbed on the resulting Si-OH substrate to increase the hydrophobicity of the membrane. Results from Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry, atomic force microscopy, and contact angle analyses suggest that the fluoroalkylsilane monolayer was successfully formed on the modified PDMS/PSf membrane treated by 60 min UV/ozone exposure. The newly SAM-modified membrane exhibited a separation factor of 13.1 and a permeate flux of 412.9 g/(m(2) h), which are higher than those obtained from PDMS membranes.