title: Elements Provide a Clue: Nanoscale Characterization of Thin-Film Composite Polyamide Membranes.
abstract: In this study, we exploit the nitrogen-sulfur elemental contrast of thin-film composite (TFC) polyamide membranes and present, for the first time, the application of two elemental analysis techniques, scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy (STEM-EDX) and X-ray photoelectron spectroscopy (XPS) C60+ ion-beam sputtering, to elucidate the nanoscale structure and chemical composition of the polyamide-polysulfone interface. Although STEM-EDX elemental mapping depicts the presence of a dense polyamide layer at the interface, it is incapable of resolving the elemental contrast at nanoscale resolution at the interfacial zone. Depth-resolved XPS C60+ ion-beam sputtering enabled nanoscale characterization of the polyamide-polysulfone interface and revealed the presence of a heterogeneous layer that contains both polyamide and polysulfone signatures. Our results have important implications for future studies to elucidate the structure-property-performance relationship of TFC membranes.
authors.affiliation: ‡State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
authors.forename: Xinglin
authors.initials: X
authors.lastname: Lu
authors.affiliation: §Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States.
authors.forename: Siamak
authors.initials: S
authors.lastname: Nejati
authors.affiliation: §Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States.
authors.forename: Youngwoo
authors.initials: Y
authors.lastname: Choo
authors.affiliation: §Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States.
authors.forename: Chinedum O
authors.initials: CO
authors.lastname: Osuji
authors.affiliation: ‡State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: §Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States.
authors.forename: Menachem
authors.initials: M
authors.lastname: Elimelech
keywords: elemental contrast; nanoscale characterization; polyamide−polysulfone interface; thin-film composite membrane