Superhygroscopic Aerogels with Hierarchical String-Bag Structure for Effective Humidity Control

Abstract

Environmental humidity regulation is crucial for diverse applications ranging from healthcare, food preservation, drug storage, to electronics protection. Herein, we employed natural cellulose as the raw material to fabricate superhygroscopic aerogels with hierarchical string-bag structure for effective humidity control. The aggregation state of cellulose chains was regulated to fabricate micronano materials, including the cellulose nanofiber network (CNFN), dendritic microfibers (CDF), and pleated microfibers (CPF), via changing the precipitation process of cellulose/ionic liquid solutions. They immobilized hygroscopic salts (LiCl, CaCl₂, and MgSO₄) to form uniform aerogels featuring micrometer macropores and nanometer string-bags. The molecular-level distribution of metal salts along the macropore wall and nanofibers, combined with the high hydrophilicity of cellulose, enabled rapid moisture absorption from the environment and transportation within the hierarchical string-bag structure. Moreover, the micronano hierarchical structure was conducive to the water storage. CNFN/LiCl aerogel demonstrated exceptional moisture absorption performance, achieving a water uptake of 1.36 and 3.14 g/g at 30% and 70% RH, respectively. Such superhygroscopic materials could rapidly and effectively control the environmental humidity, indicating a huge potential in food preservation, healthcare, and environmental regulation.