Hydrophobic and Adhesive Elastomer Encapsulation for Anti‐Drying, Non‐Swelling, and Adhesive Hydrogels

Abstract Traditional hydrogels often face issues like dehydration, excessive swelling, and poor adhesion, limiting their practical applications. This study presents a facile and universal method to create elastomer‐encapsulated hydrogels with improved water retention, non‐swelling, and enhanced adhesion. n‐Butyl acrylate (BA) and 2,2,3,4,4,4‐hexafluorobutyl methacrylate (HFBMA) are utilized as the “soft” and “hard” monomers, respectively, to in situ construct the elastomer coatings on the hydrogel surface through surface‐confined copolymerization. The resulting transparent, hydrophobic, and adhesive elastomer coating is tightly bound to the hydrogel surface, conferring upon it a robust defense against dehydration and swelling in various media, and strong adhesion to diverse substrates in both aerial and submerged conditions. Furthermore, this encapsulation strategy also augments the mechanical attributes of the bulk hydrogel, including its tensile properties and puncture resistance, and is applicable to a wide array of hydrogel types and configurations. Additionally, the in situ encapsulation method applied to conductive hydrogels results in flexible sensors with high sensitivity, reversible resistance change, exceptional sensing stability, and significantly enhanced durability in both air and underwater environments. These properties suggest potential applications in harsh environments, such as underwater acoustic detection and sonar scanning camouflage for submarines.