A Quenched Double-Hydrophilic Coating for the Enhancement of Water Retention of Hydrogels

With the emergence of various hydrogels with excellent functions, the air-drying of hydrogels has attracted extensive attention. Improving the water retention capacity is critical in the application of hydrogels. Herein, inspired by the dense aggregation structure of natural hydrophilic macromolecules, hydrophilic substances (gelatin and glycerol) are first applied to enhance the water retention capacity of hydrogels by constructing a quenched double-hydrophilic coating. The weight retention ratio of the modified hydrogels is increased to 72.5% at 25 °C and 40 RH% after 5 days. Furthermore, the construction of hydrophilic coating on the surface does not affect the mechanical properties, and the modified hydrogels still retain strong water retention capacity after loading. In addition, this approach is applicable to hydrogels with different shapes and types, and various materials can be selected. Therefore, the proposed method provides new insights for expanding the application scope and service life of hydrogels.