Biomimetic Super Anti-Wetting Coatings from Natural Materials: Superamphiphobic Coatings Based on Nanoclays

Abstract

Superamphiphobic coatings (SAPCs) that resist wetting of water and low-surface-tension liquids have generated widespread attention in academia, but are very challenging to invent. Liquid adhesion, low stability, complicated and expensive preparation methods are the typical characteristics of SAPCs, which seriously hinder real-world applications of SAPCs. Here, we report a comprehensive study about preparation of SAPCs from abundant nanoclays with fibrous, plate-like and porous microstructures. The SAPCs are prepared simply by hydrolytic condensation of silanes in the presence of nanoclays, followed by spray-coating the as-formed suspensions onto substrates. The SAPCs feature high superamphiphobicity for various liquids down to a surface tension of 23.8 mN m−1 (n-decane), and high mechanical, chemical and thermal stability. The superamphiphobicity and stability depend on microscale and nanoscale surface morphology of the coatings, which are controllable by the microstructures of nanoclays and their acid activation. The fibrous nanoclays with moderate aspect ratio like palygorskite are the most suitable building blocks for the preparation of SAPCs by effectively forming the reentrant surface morphology. We believe that the findings will promote the progress of SAPCs, and pave the way for the development of clay-based super anti-wetting coatings.