A　series　of　thin-film　composite　(TFC)　polyamide　membranes　was　fabricated　through　interfacial　polymerization　on　a　modified　polyacrylonitrile　(mPAN)　substrate,　where　an　aqueous　solution　of　diamine　was　reacted　with　an　organic　solution　of　diacyl　chloride.　Various　monomers　were　used:　two　different　diamines　[1,3-diamino-2-propanol　(DAPL)　and　hydrazine]　and　two　different　diacyl　chlorides　[succinyl　chloride　(SCC)　and　trans-5-norbornene-2,3-dicarbonyl　chloride].　Combining　these　monomers　resulted　in　a　new　polyamide　layer.　We　investigated　the　effect　of　the　monomer　chemical　structure　and　interfacial　polymerization　conditions　on　the　membrane　pervaporation　performance　in　dehydrating　an　aqueous　solution　of　ethanol.　According　to　field　emission　scanning　electron　microscopy,　DAPL-SCC　provided　the　thinnest　polyamide　layer,　which　was　also　confirmed　through　positron　annihilation　lifetime　spectroscopy.　The　results　were　used　to　correlate　the　variation　in　the　membrane　microstructure　with　the　pervaporation　performance　of　the　fabricated　TFC　polyamide　membranes.　Both　microstructural　characteristics　and　surface　properties　affected　the　pervaporation　performance.　DAPL-SCC/mPAN　membranes　with　lower　free-volume　sizes　and　suitable　hydrophilicity　were　evaluated　to　deliver　the　highest　water　concentration　in　permeate　and　the　lowest　permeation　flux　(on　the　basis　of　the　pervaporative　dehydration　of　an　aqueous　solution　of　90　wt%　ethanol　at　25　degrees　C).