Polyanion/polycation bilayer coating membranes fabricated by successively coating sulfonated poly(arylene ether ketone)s and quaternized polysulfone on ultrafiltration membranes

The anionic or cationic aromatic polymers coating membranes are antifouling, but their rejection for MgSO 4 is low. In this work, soluble sulfonated poly(arylene ether ketone)s (sPAEKs) in commonly polar solvents is synthesized by incorporating methyl side groups. Such sPAEKs thus could be coated on commercial ultrafiltration membranes to make the sPAEKs coating membranes without damaging the pore structure of ultrafiltration supports. On this basis, quaternized polysulfone (qPSF) is coated on the sPAEKs layer to prepare the anionic/cationic polymers crosslinked membranes. This ionic crosslinking between the anionic and cationic polymer layers remarkably reduces the molecular weight cut-off of the coating membranes. The hydrophilic charged coating layers are also favorable for antifouling and enhancing permeation flux. In addition, the aromatic backbones of sPAEKs and qPSF are beneficial for improving chlorine resistance. As a result, the as-made membranes exhibit excellent nanofiltration performances. For example, one of them shows a permeation flux of 10.3 LMH/bar, a MgSO 4 rejection of 98.2%, a flux recovery rate (FRR) of 98.6% for bovine serum albumin. It also displays high rejection for MgSO 4 after 40,000 ppm·h of continuous exposure to NaClO solution. High-performance nanofiltration membranes are fabricated by successive bilayer coating of aromatic polyanions and polycations on ultrafiltration supports for the first time, this strategy shows significant application prospects.