Applications of positron annihilation to polyamide membranes

Positron annihilation spectroscopy (PAS) has been used to study the depth profile (0 - 8 µm) in a membrane system containing a thin layer of polyamide prepared by the interfacial polymerization of triethylenetetraamine (TETA) and trimesoyl chloride (TMC) onto the surface of asymmetric polyacrylnitrile (PAN). Doppler broadening S parameters of annihilation radiation energy spectra show a systematic variation with the doping time of TETA in the membrane preparation process of interfacial polymerization. The layer structures of composite membrane are obtained. A similar variation between S parameters with respect to TETA doping time and permeability but an anti-correlation between S parameter and selectivity are observed. Future applications of PAS and slow positron beam to membrane technology appear to be promising. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)