Novel Membrane Adsorbers with Grafted Zwitterionic Polymers Synthesized by Surface-Initiated ATRP and Their Salt-Modulated Permeability and Protein Binding Properties

Abstract

A novel zwitterionic polymer functionalized porous membrane adsorber was obtained by grafting poly(N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine) (polySPE) to poly(ethylene terephthalate) (PET) track-etched membrane surface via surface-initiated atom transfer radical polymerization (SI-ATRP). The ATRP conditions were optimized, the thus established grafting was well-controlled, and the degree of grafting could be adjusted. Functionalized membranes with a degree of grafting of about 3.5 μg/cm2 relative to the specific surface area showed almost zero values of zeta potential estimated from the trans-membrane streaming potential measurements. Typical “anti-polyelectrolyte” effect was observed for the polySPE grafted membranes. Flux through the membrane was reduced by adding chaotropic chloride and perchlorate salts to the solution which extended the polySPE chains grafted on the membrane pore wall. Perchlorate salt exhibited much stronger effect on polySPE chain conformation than chl...