Superamphiphobic Surfaces with Self-Cleaning and Antifouling Properties by Functionalized Chitin Nanocrystals

Superamphiphobic coating has significant applications in self-cleaning and antifouling materials. Herein, chitin nanocrystals (ChNCs) with a needlelike morphology as building blocks were modified by thiol groups and highly fluorinated long chains to reduce the surface free energy. For the prepared superamphiphobic ChNC particles, a series of morphological and physicochemical characterizations, such as transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy, were performed. The superamphiphobic ChNC particles feature high contact angles and low sliding angles for various liquids, including n-decane with a low surface tension (23.3 mN/m). Different liquid droplets can retain a perfectly quasispherical shape on the coating surface. Most interestingly, liquid marbles wrapped up by this superamphiphobic powder can "stand" on various substrates without any collapse. The coating shows a good repellency for liquids after the mechanical damage tests and thermal treatments. In addition, the superamphiphobic ChNC particles could be applied onto various substrates, exhibiting a good resistance and substrate-independent performance. In sum, the fluorinated ChNC coatings with superior superamphiphobicity, substrate independence, and stable mechanical and thermal properties show promising applications of water/oil-proof, self-cleaning, and antifouling coatings.