Underwater superpolymphobic amyloid-like protein coating for polymer separation

Abstract

The widespread use of liquid polymers leads to significant waste and environmental pollution due to their leakage into water, and their removal is challenging due to their high viscosity, low fluidity, and strong adhesion. In this study, we introduce a superpolymphobic amyloid-like protein (ALP) coating for the removal of liquid polymers from water. The composite ALP coating, composed of phase-transitioned lysozyme and oxidized cellulose nanocrystals, was applied to a stainless-steel mesh. This ALP-coated mesh demonstrated excellent underwater superpolymphobicity with a polymer contact angle of 167.7 ± 1.1° and a sliding angle of 1.3 ± 0.1°. The coated mesh effectively repelled various liquid polymers (such as polydimethylsiloxane, epoxy resins, and silicone oils), enabling efficient separation of polymer/water mixtures with a separation efficiency of 99.49 %. The coating exhibited remarkable mechanical and chemical stability, maintaining its performance after multiple cycles of use and stringent durability tests, including bending, sandpaper abrasion, ultrasonic treatment, tape peeling, flushing, and exposure to acidic or alkaline solutions. The ALP coating can be applied to commercially available pre-filters, resulting in the production of pure water free from polymer contaminants. Furthermore, the coating can be regenerated for infinite recycling by simply spraying it on. This approach demonstrates direct applicability for retrofitting existing water purification systems, exhibiting enhanced biocompatibility and superior mechanical stability while providing a simple, mild, and scalable strategy to address polymer contamination in aquatic ecosystems.