Synergistic design of a robust superhydrophobic ZIF 8/PDMS/PI composite membrane for integrated oil water separation, photocatalysis, and anti biofouling

Synergistic coating design combining ZIF-8 and PDMS on a porous PI substrate. • Integrated multifunctionality enabling oil-water separation, photocatalytic degradation, and anti-bioadhesion. • Exceptional separation performance with a water contact angle of 162.8° for various oil-water mixtures. • Outstanding environmental durability demonstrated against mechanical abrasion, UV aging, and acid/alkali corrosion. The treatment of wastewater containing oils and organic pollutants remains a critical environmental challenge. Traditional separation membranes often lack the multifunctionality needed for simultaneous separation, degradation, and antifouling. In this study, a robust superhydrophobic composite membrane was fabricated via a facile solution-impregnation method, in which zeolitic imidazolate framework-8 (ZIF-8) nanoparticles were integrated with polydimethylsiloxane (PDMS) onto a porous polyimide (PI) substrate. The designed coating synergistically combines the micro-/nano-scale roughness of ZIF-8 with the low surface energy of PDMS, endowing the membrane with a water contact angle of 162.8 ± 0.3° and a sliding angle of 3.0 ± 0.4°. The composite membrane demonstrates high-efficiency separation of various oil-water mixtures (>95% efficiency, flux >9000 L·m −2 ·h −1 ), effective photocatalytic degradation of methylene blue (MB) under ultraviolet (UV) light (93.7% within 2.5 h), and excellent anti-bioadhesion performance against Chlorella vulgaris. Moreover, the membrane retains its superhydrophobicity after mechanical abrasion, tape peeling, UV aging, and exposure to acidic/alkaline environments, confirming outstanding durability. This work presents a scalable strategy for developing multifunctional PI-based membranes with integrated separation, catalytic, and antifouling properties, showing promising potential for practical water remediation applications. Download: Download high-res image (268KB) Download: Download full-size image