Permeation behavior of polysulfone membranes modified by fully organic layer-by-layer assemblies

This paper investigates the effect of the deposition of layer-by-layer (LbL) assemblies on the swelling, permeability, and anthracene rejection of polysulfone (PSf) membranes obtained through a phase inversion precipitation technique. More specifically, the latter have been dip-coated on one side with a completely organic assembly (made of poly(acrylic acid)/branched polyethyleneimine bilayers), varying the number of deposited bilayers (BL) from 10 BL to 20 BL. Prior the deposition, the surface of the polysulfone membranes has been subjected to plasma activation. Static contact angle, scanning electron microscopy, and attenuated total reflectance infrared spectroscopy measurements have been exploited for evaluating the modification of polysulfone after the LbL deposition, as well as the homogeneity of the distribution and coverage of the coatings on the polymeric substrate. The swelling of both untreated and LbL-treated membranes has been evaluated in three different solvents, i.e., methanol, isopropanol, and n-hexane; subsequently, the permeation features of the treated membranes toward these solvents have been assessed and correlated with the presence of the deposited assembly; finally, the retention of anthracene in its n-hexane solutions has been evaluated.