Versatile fabrication of hydrogel coatings with shell powder as a key Ingredient

While hydrogel coatings have garnered considerable attention in recent years, the utilization of bioresources has been largely overlooked in existing preparation strategies. This study presents a hydrogel coating fabrication method utilizing shell waste-derived shell powder (SP) as a key resource, termed shell powder acidolysis triggered in situ gelation (SP-ATIG). By integrating a SP containing tannic acid-polyvinyl alcohol primer (PVA-TA/SP layer) with sodium alginate, the SP-ATIG method enabled the formation of hydrogel coatings on both flat and irregular surfaces of various substrates (e.g., glass, plastics, metals) with controllable thickness. This method is also capable of constructing dual-network hydrogel coatings, providing substrates with tailored functional surfaces. Moreover, it endowed the resulting hydrogel coatings with patterning capabilities, lubricity, and anti-oil properties, offering them potential applications such as information transmission, self-lubricating materials, and anti-fouling coatings. This work highlights the innovative use of waste bioresources to develop versatile hydrogel coatings, providing a sustainable alternative for advanced functional surface fabrication.