Protein fractionation of pH‐responsive brush‐modified ethylene vinyl alcohol copolymer membranes*

Abstract Protein fractionation and purification remain challenging in membrane separation. Herein, a pH‐responsive membrane was developed by grafting the brush‐like poly(dimethylaminoethyl methacrylate) (PDMAEMA) via ATRP onto the ethylene vinyl alcohol copolymer (EVAL) membrane for protein fractionation. The PDMAEMA brushes are distributed in all pore channels of the membrane. Based on the electrostatic and sieving properties of the as‐prepared pH‐responsive membrane, three milk proteins are successfully separated from their mixture. The α‐Lactalbumin (α‐LA) preferentially permeates the membrane from the mixture at pH 3.2, and the bovine serum albumin (BSA) and lactoferrin (LF) can be separated at pH 6.4 based on the selective adsorption. This work proposes a promising candidate for protein separation by a pH‐responsive membrane.