Salt-doped cellulose hydrogels with tunable LCST and dynamic transparency for information encryption

With the rapid advancement of information technology and the increasing demand for data security, the development of information encryption materials and technologies with multidimensional responsiveness has become an important research focus in recent years. Herein, a salt-doped cellulose hydrogel was fabricated via a one-pot strategy using hydroxypropyl cellulose (HPC), acrylamide (AAm), and calcium chloride (CaCl 2 ) as the starting materials. The strong hydration capability of CaCl 2 alters the structure and activity of water molecules, thereby restricting their mobility within the hydrogel network. By varying the CaCl 2 concentration, the hydrogel exhibits a tunable lower critical solution temperature (LCST) within the range of 22–35 °C. Furthermore, the rehydration kinetics of the polymer chains during the cooling process can be effectively regulated, enabling dynamic transparency transitions over a timescale of 100–400 s. By assembling hydrogels with varied CaCl 2 concentrations on a label, multilevel information encryption and dynamic data storage were achieved in temporal and thermal dimensions.