Post-functionalization of carboxylic polyethersulfone composite membranes

Herein, a new and facile approach by in situ cross-linking polymerizationcoupled with a post-functionalization procedure was developed to prepare functional PES composite membranes to improve its over-all performance as hemodialysis membrane. In our strategy, poly(acrylate acid-co-2-hydroxyethyl methacrylate) P(AA-co-HEMA) as a macromonomer, was firstly synthesized by free radical copolymerization, then blended in PES solution and in situ cross-linked polymerization via the reaction of the hydroxy group of HEMA and the isocyanate group of 4,4′-diphenylmethane diisocyanate (MDI) to prepare the carboxylic membranes. To further enhance the hemocompatibility, the carboxylic membranes were post-functionalized by grafting sulfonic acid groups onto the membrane surfaces via a “grafting from” method. The chemical compositions and surface morphologies of the prepared membranes were investigated by ATR-FTIR, XPS, SEM and AFM. After introducing the functional groups, the surface hydrophilicity of the membranes was significantly improved, demonstrated by the reduced water contact angles (WCAs) and enhanced permeability. The decreased protein adsorptions and higher flux recovery ratios (FRRs) revealed that the modified membranes showed improved protein antifouling property. The improvement of hemocompatibility was confirmed by the inhibited platelet adhesion, prolonged clotting times, and suppressed blood-related complement activation. Moreover, the post-functionalized membranes also showed good cytocompatibility. In general, the in situ cross-linking technique is a suitable route in the field of membrane modification for its facile and easy operation; and the post-functionalization operation could endow the membranes with efficiently improved properties.