Skin‐Inspired Double‐Hydrophobic‐Coating Encapsulated Hydrogels with Enhanced Water Retention Capacity

Abstract Traditional hydrogels always lose their flexibility and functions in dry environments because the internal water inevitably undergoes evaporation. In this study, a skin‐inspired, facile, and versatile strategy for developing encapsulated hydrogels with excellent water retention capacity through a double‐hydrophobic coating is proposed. The robust double‐layer coating, which integrates a hydrophobic polymer coating with a hydrophobic oil layer simultaneously, can provide a barrier to prevent the evaporation of water. To overcome the weak interfacial strength between the hydrophilic hydrogel surface and the double‐hydrophobic coating, (3‐aminopropyl) triethoxysilane (APTES) is utilized as a chemical binding agent. Furthermore, the overall mechanical properties of the bulk hydrogel are not significantly affected, because the coating is only anchored to the surface and its thickness is much lower than that of the native hydrogel. Moreover, it is demonstrated that this proposed strategy particularly holds the capability of encapsulating various types and different shapes of hydrogels, leading to enhanced stability and a prolonged lifetime in air. Therefore, the proposed technology provides new insights for multifarious surface functionalization of hydrogel and broadens the range of hydrogel applications.