F127-based multi-block copolymer additives with poly(N,N-dimethylamino-2-ethyl methacrylate) end chains: The hydrophilicity and stimuli-responsive behavior investigation in polyethersulfone membranes modification

F127-based (F127, PEO-b-PPO-b-PEO) amphiphilic block copolymers containing poly(N,N–dimethylamino-2-ethyl methacrylate) (PDMAEMA) end blocks (F127-b-PDMAEMAn) were used as additives in the polyethersulfone (PES) porous membranes preparation by phase inversion method. The membrane properties and morphologies were characterized by contact angle measurements, porosity analysis, scanning electron microscope (SEM) and water permeation tests. Compared to the F127, water contact angle results showed that the synthesized copolymers were more effective in improving the membranes hydrophilicity, and better hydrophilicity was obtained for additives with longer PDMAEMA blocks. Porosity data and SEM observation showed that the usage of F127-b-PDMAEMAn led to smaller pore size compared with F127, which might attribute to the altered membrane-forming process by an increased entanglement of F127-b-PDMAEMA with PES. The water permeation results indicated that the additives F127-b-PDMAEMA had endowed membranes with smart properties that responded to temperature and pH stimulations. While the synthesized additives caused the blend membranes to adsorb more proteins than the F127 did, which was assigned to the weak polyelectrolyte property of the PDMAEMA blocks.