Defect free pervaporation mixed matrix membranes fabricated on ZIF-8 surface segregation substrates

Abstract

Mixed matrix membranes (MMMs), which incorporate porous particles into polymer matrix, were a promising approach to overcome the inherent trade-off effect of polymeric membranes. Controllable and easily scalable membrane fabrication strategies remained a challenge for the development of defect-free pervaporation MMMs. In this work, to avoid defects formed by particle exposure in MMMs, forced surface segregation of ZIF-8 on a substrate was achieved by vapor-assisted non-solvent induced phase separation (NIPS) process. Subsequently, ZIF-8 ‘islands’ on the substrate surface were sealed with PVA solution and defect-free dense MMMs were successfully prepared. The surface segregation of ZIF-8 was proved by scanning electron microscope (SEM), X-Ray diffraction (XRD) and fourier transform infrared (FTIR). The prepared MMMs showed an increase in flux of 162% and an increase in separation factor of 299% compared to the pristine membranes. It was expected that this strategy of inducing particles to undergo forced surface segregation could be extended to the preparation of other membranes.