A new route to mixed matrix membranes: Atomic layer deposition of TiO₂ on membrane-forming polymers followed by nonsolvent-induced phase inversion

Mixed matrix membranes (MMMs) are emerging as a novel class of advanced membranes. Versatile nanofillers are usually applied to improve the separation performance of MMMs. However, the poor compatibility and dispersibility of nanofillers cause inner defects in the polymeric matrix, which degrades the separation performance of MMMs. To solve this problem, we introduce atomic layer deposition (ALD) to modify polyacrylonitrile (PAN) powders and use them to fabricate high-performance PAN-TiO₂ MMMs by the nonsolvent-induced phase separation method. Thanks to the advantages of ALD, the thickness of TiO₂ is precisely tuned and the interaction between TiO₂ and PAN matrix is established during the ALD process. Therefore, the fine size and non-covalent interactions make TiO₂ disperse homogeneously in the membrane matrix and enhance the porosity of PAN-TiO₂ MMMs. The PAN-TiO₂ MMMs fabricated by 500-cycle-deposited PAN powders show a 46.5 % higher permeance without consuming the selectivity. Moreover, MMMs possess better antifouling properties, which show lower contaminant adsorption and a better permeance recovery of 86.4 % in dynamic antifouling tests.