Spinning‐assist layer‐by‐layer assembled polysulfonamide membrane for reverse osmosis from naphthalene‐1,3,6‐trisulfonylchloride and piperazine

ABSTRACT Polysulfonamide (PSA), with its chemical stability and acid‐resistance, is seen as a potential material for reverse osmosis. However, the present PSA thin film composite membranes fabricated via prevailing interfacial polymerization (IP) approach generally exhibited nonfavored desalination performance. In this work, PSA membrane was assembled via spinning‐assist layer‐by‐layer (sLbL) on a poly(vinyl alcohol) modified polyethersulfone substrate. Fabrication was carried out through sequential interfacial reaction between naphthalene‐1,3,6‐trisufonylchloride and piperazine by alternately dipping and drying the substrate in two monomer phases. Morphology, chemical composition, surface charge distribution as well as surface hydrophilicity were investigated as a function of repeated cycles. The sLbL assembly approach implemented facile control over membrane properties with well‐organized selective layer thickness growth and twofold to threefold reduced surface roughness. As measured from spectroscopic ellipsometry, the sLbL assembled membranes exhibited a linear thickness growth at ~2.72 nm per layer. Performance test indicated that the salt rejection and water flux showed a trade‐off pattern with increasing layer number. The PSA membrane with five layers showed a preferable NaCl rejection of 95.7 ± 0.4% with a water flux of 12.4 ± 0.9 L m −2 h −1 at 10 bar, whereas the IP membrane exhibited only 58% and a 22.12 L m −2 h −1 flux. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47138.