Fabricating a pH-responsive membrane through interfacial in-situ assembly of microgels for water gating and self-cleaning

Environmental stimuli-responsive membranes have many latent applications in numerous fields, for example, chemical/biological separations, water treatment, drug delivery, self-cleaning material and chemical sensor. In this study, a pH-responsive membrane with in-situ assembled stimuli-responsive microgels on membrane surface and internal channels wall was fabricated by the coagulation step of the phase-inversion process. Interestingly, it was found that poly(4-vinyl pyridine) (P4VP) microgel can be mobilized onto the membrane surface by using an acidic coagulation bath. Meanwhile, the membrane-based materials with different hydrophobic properties showed a great effect on the migration of microgel onto the channel surface. The inner pores of these responsive membranes can self-adjust its size with the changes of outside pH stimulus. Moreover, the gate-controlled water permeability of pH-responsive membranes was explored at the pH interval from pH 2 to pH 6. Investigations revealed that the P4VP microgel-assembled membrane had excellent pH-responsive performance. In addition, these pH-responsive membranes with embedded microgels on surface and inner pores wall also exhibited excellent reversible behaviors and self-cleaning properties.