Structure formation in pH-sensitive micro porous membrane from well-defined ethyl cellulose-g-PDEAEMA via non-solvent-induced phase separation process

To clarify the structure formation in pH-sensitive cellulose based micro porous membrane in non-solvent-induced phase separation process, first, a series of ethyl cellulose-graft-poly(2-(diethylamino)) ethyl methacrylate) (EC-g-PDEAEMA) with different graft density and graft length were synthesized via atom transfer radical polymerization (ATRP). The results of the micelles characterized by UV, Laser particle analysis and TEM indicated that the copolymer had pH responsive behavior and the increase of grafting density and grafting length led to the decrease of critical pH value. Furthermore, the morphology study of micro porous membrane via the NIPS process from mixture of THF and DMF indicated that the pores became smaller and more uniform with the increase of THF content and “open time”, and the most optimal preparation conditions was using EC0.2-g-PDEAEMA32 as the film-forming material and 75%THF/25%DMF (v/v) as solvent with the “open time” 1 min. What’s more, the membrane was responsive to pH stimulus in terms of water flux and demonstrated by scanning electron microscopy.