Cellulose-Nanocrystal-Promoted Underwater Superoleophobic Wrinkles on Hydrogel Surfaces

The surfaces of hydrogels need to be modified to endow them with antifouling properties in water. In this study, hydrophilic cellulose nanocrystals (CNCs) are assembled on hydrogel surfaces to form wrinkled microstructures that endow the hydrogel surfaces with superhydrophilicity. To that end, anionic CNCs are attached to the surface of a cationic gel via electrophoresis to induce hydrogel wrinkling, with the wavelength and amplitude of the wrinkles controlled by adjusting the elastic modulus of the hydrogel. An elastic mismatch between the hydrogel and CNC layer leads to the formation of the wrinkled structure. The wrinkled gel surface exhibits a smaller water contact angle in air than the corresponding flat surface, and oil does not adhere to the wrinkled surface in water. The developed hydrogel-coating method is simple, clean, and cost-effective, and the wrinkled surfaces prepared using these CNCs are promising antifouling coatings for use in water.