Double stimuli-responsive isoporous block copolymer membranes upon phase separation strategies

Abstract

Isoporous membranes from block copolymer commonly involves in the self-assembly and non-solvent induced phase separation (SNIPS), which could improve the selectivity and water permeance. However, such strategy face challenges: (1) to prepare poly (acrylic acid) PAA based block copolymer isoporous membrane with SNIPS method is difficult since PAA is extremely hydrophilic; (2) large consumption of block copolymer and non-solvent (water) might limit its application. Herein, isoporous membranes from Polystyrene-block-poly (acrylic acid) (PS-b-PAA) were well prepared with amine terminated poly(N-isopropylacrylamide) (pNIPAM-NH2) through the SNIPS and the airflow accelerated evaporation induced phase separation methods (acEIPS). Such membranes bear not only regularity in morphological structure, but also high water permeance (1500 L h−1 m−2 bar−1 for the SNIPS, and 3000 L h−1 m−2 bar−1 for the acEIPS). With the participation of pNIPAM-NH2 the consumption of the block copolymer is limited to 7.8 wt % for the SNIPS method, and even to 5.3 wt % for the acEIPS method without non-solvent precipitation process. Besides, the membrane exhibits pH and thermal responsiveness.