Jean Y.C.Hung W.-S.Lo C.-H.Chen H.Liu G.Chakka L.Cheng M.-L.Nanda D.Tung K.-L.Huang S.-H.Lee K.-R.Lai J.-Y.Sun Y.-M.Hu C.-C.Yu C.-C.2019-05-242019-05-24200800119164https://scholars.lib.ntu.edu.tw/handle/123456789/410502Positron annihilation spectroscopy (PAS) coupled with a slow positron beam has been used to study the freevolume depth profile (0-10 £gm) in polymeric membrane systems prepared by the interfacial polymerization method. Doppler broadening energy parameters of annihilation radiation vary as a function of the depth from the surface through multi-layers in polyamide asymmetric membranes prepared under different experimental parameters, such as the time, the temperature, and pH of membrane preparation process of interfacial polymerization. Three layer structures including a skin, a transition, and the porous layers in those asymmetric membrane systems are obtained. Positron annihilation lifetime results provide additional information about free-volume size and distribution in nano- and micro-scale film membrane systems. PAS results are correlated with the pervaporation separation, flux and water wt% in permeate of 70% isopropanol aqueous solution and compared with the SEM images. ? 2008 Elsevier B.V. All rights reserved.Free volumeInterfacial polymerizationPolymeric membranePositron annihilation spectroscopySlow positron beamjournal article10.1016/j.desal.2007.09.0742-s2.0-55049124749https://www.scopus.com/inward/record.uri?eid=2-s2.0-55049124749&doi=10.1016%2fj.desal.2007.09.074&partnerID=40&md5=1f6ed03e75090af40ef68d574fd3d736