Waterborne robust superamphiphobic coatings based on palygorskite for self-cleaning and anti-fouling

Superamphiphobic coatings have garnered great attention owing to their widespread application potential in self-cleaning, anti-corrosion, anti-fouling and anti-icing, etc. However, environmentally harmful material, complicated preparation methods, and poor mechanical stability significantly hamper their applications. Here, we report preparation of waterborne durable superamphiphobic coatings based on palygorskite. The coatings were prepared by in turn spray-coating a waterborne polyurethane adhesive solution (the primer layer) and a homogenous aqueous suspension of siloxane-modified palygorskite (the top layer) onto substrates. The influences of concentration palygorskite, silane and catalyst on morphology and wettability of the coatings were studied. Because of microstructure of palygorskite and low surface energy of siloxanes, the coatings have a re-entrant hierarchical micro-/nanostructure with low surface energy. Consequently, the coatings exhibit excellent superamphiphobicity and chemical stability. Moreover, the coatings show good mechanical stability because the siloxane-modified palygorskite top layer was firmly affixed on the substrate by the adhesive layer. In addition, the coatings exhibit good anti-fouling and self-cleaning properties. This study demonstrates a new method for the preparation of superamphiphobic coatings and a new application of natural fibrous clay minerals like palygorskite.