Double Stimuli-Responsive Isoporous Membranes via Post-Modification of pH-Sensitive Self-Assembled Diblock Copolymer Membranes
AbstractDouble stimuli-responsive membranes are prepared by modification of pH-sensitive integral asymmetric polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymer membranes with temperature-responsive poly(N-isopropylacrylamide) (pNIPAM) by a surface linking reaction. PS-b-P4VP membranes are first functionalized with a mild mussel-inspired polydopamine coating and then reacted via Michael addition with an amine-terminated pNIPAM-NH2 under slightly basic conditions. The membranes are thoroughly characterized by nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy and X-ray-induced photoelectron spectroscopy. Additionally dynamic contact angle measurements are performed comparing the sinking rate of water droplets at different temperatures. The pH- and thermo-double sensitivities of the modified membranes are proven by determining the water flux under different temperature and pH conditions.