A novel reverse osmosis hollow ?ber membrane was prepared by interfacial polymerization from 3,3,5,5-biphenyl tetraacyl chloride and m-phenylenediamine on a polysulfone hollow ?ber membrane.The structural evolution of biphenyl polyamide thin ?lmduring interfacial polymerizationwasmonitored by attenuated total re?ectance infrared, X-ray photoelectron spectroscopy and atom force microscopy.The relationship between the structure and separation properties of the membranes was investigated.Results show that the biphenyl polyamide thin ?lmhad a three-layer structure: a loose initial layer with a low cross-linked structure, a dense middle layer with a high cross-linked structure and a loose surface layer with a low cross-linked structure. The dense middle layer had an intrinsic cross-linked structure with over 86.0% amide bonds (–CONH–) and below 14.0% carboxylic groups (–COOH), mainly respon-sible for separation. A growth model of the biphenyl polyamide thin ?lm was proposed to describe the structural evolution process during interfacial polymerization.
