A Facile Method for Processing Durable and Sustainable Superhydrophobic Chitosan-Based Coatings Derived from Waste Crab Shell

The substitution of synthetic raw materials with renewablefeedstock is fueling a lot of interest to drive new scientific and technicaladvancements that underpin this strategy. In this context and looking at thebroad prospect of chitosan, herein, we proposed a facile, economical, andnovel strategy to process high-yield (44%+/- 3) chitosan from waste crabshells and apply the processed chitosan to fabricate a durable, multifunc-tional, ecofriendly superhydrophobic coating. The coating was developed bybinding the amines of chitosan and a long-chain polymer, octadecylamineusing a cross-linking agent (glutaraldehyde). Applying the coating ontointrinsically hydrophilic polyester fabric and typical surgical-grade cotton yielded superhydrophobic materials with water contactangles of 158.6 and 161.4 degrees(+/- 3), respectively. A preliminary study revealed that the coating could endure multiple cycles of laundry(60x), sandpaper abrasion (55x), and tape peel test (80x) with little diminution in the superhydrophobic property. Interestingly,any decrease in the superhydrophobicity could be restored after ironing the fabrics for 2 min, indicating that the effect was reversible.Furthermore, the coating could transform an ordinary hydrophilic polyurethane sponge into an excellent superhydrophobic-superoleophilic absorbent, which can rapidly absorb and separate a variety of organic solvents and oils from oil/water mixtures.