Environment-Friendly Antibiofouling Superhydrophobic Coatings

Hydrophobic surfaces have the potential to enhance the efficiency of a plethora of applications, from heat exchangers, to underwater structures, to food industry and oil–water filtration. A large fraction of currently available hydrophobic coatings consist of perfluorinated compounds or organosilane-based chemistries, both of which can be toxic and bioaccumulate in nature. Here, we develop environmentally friendly and economical superhydrophobic coatings using naturally abundant sepiolite nanoparticles functionalized with naturally extracted fatty acids from cinnamon and myristica. We demonstrate our coating on a variety of metallic and nonmetallic surfaces with dip-coating of aluminum, absorbent fabrics, glass, and even paper. Contact angle measurements revealed the ability to scalably produce high apparent advancing contact angles (>160°) with low contact angle hysteresis (<5°). We characterized our coated surfaces for their antibiofouling characteristics using Gram negative and Gram positive bacteria. The results showed that the bacterial attachment considerably decreased (<5%) compared to the untreated surfaces (∼30%), resulting in lower biofouling. The chemical, mechanical, and thermal durabilities of the coating were studied, with results showing that immersing the samples in different pH aqueous solutions (4 ≤ pH ≤ 10) and exposing the samples to different temperatures (T < 200 °C) for various times does not have a significant effect on the superhydrophobicity of the samples. Our work not only presents the development of naturally-derived and environment-friendly superhydrophobic antibiofouling coatings, it demonstrates a pathway for future research on the development of sustainable and ecological functional coatings.