Design Rules for Cross-Linking and Initiation in Functional Chitosan Hydrogels for Environmental Applications

Abstract Chitosan-based hydrogels have various applications in atmospheric water harvesting (AWH). These hydrogels exhibit good water absorption, compatibility with living systems, a 3D porous structure, and high water uptake and release capacity. The effectiveness of hydrogels depends primarily on cross-linking agents and initiators, as each type of cross-linker influences the overall stability, mechanical properties, swelling capacity, moisture absorption, and other characteristics of the polymer network. Recently, new cross-linking agents and initiators have been explored to develop properties that would enable chitosan-based hydrogels to serve as an environmentally friendly means of collecting atmospheric water. In this review, we discuss the most recent advances in cross-linking technology and the procedures required to produce a composite capable of harvesting atmospheric water, with a focus on desorption and cycling stability. Finally, we discuss the current barriers and future opportunities for this research area.