Influence of substrate processing and interfacial polymerization conditions on the surface topography and permselective properties of surface-patterned thin-film composite membranes

The influence of substrate topography and interfacial polymerization (IP) conditions were investigated during the fabrication of patterned thin-film composite (TFC) membranes. Aromatic and semi-aromatic polyamide layers were formed atop patterned ultrafiltration (UF) membrane supports by IP using different concentrations of m-phenylenediamine (MPD) or piperazine (PIP) in water of 0.01-2% w/v with a fixed concentration of trimesoyl chloride in hexane of 0.1% w/v. For all the conditions evaluated, TFC membranes with regular surface patterns were achieved by maintaining amine soaking time and IP reaction time within 120 s. Importantly, the surface topography of the patterned TFC membranes was determined to be independent of IP reaction time. Characterization of the morphological details suggests non-conformal growth of the barrier layer on the patterned UF substrates. Results indicate that the extent of such non-conformal growth can be reduced by decreasing the amine concentration as well as by choosing an amine monomer such as PIP that produces a thinner semi-aromatic barrier layer. The overall findings of this study provide a means for achieving desired surface features for specific membrane applications. (C) 2016 Elsevier B.V. All rights reserved.