Multistimuli-Responsive Conductive Hydrogels for Information Encryption, Decryption, and Wearable Sensors

Stimuli-responsive hydrogels have emerged as one of the most promising candidate materials in the fields of bionic materials and artificial intelligence due to their unique stimulus responsiveness and dynamic reversibility. To overcome the limitations of single-response factors and poor responsiveness in existing stimuli-responsive hydrogels, an ionically conductive hydrogel with excellent transmission properties and multistimuli-responsive information encryption and decryption at room temperature was developed. A temperature/ethanol/salt stimuli-responsive conductive hydrogel (PPSD) was synthesized by a one-pot method in a salt solvent, using SDS, NIPAm, PVA, and SGA₁₅ as raw materials. By incorporating SDS, known for its low-temperature sensitivity, together with a high-temperature-sensitive monomer featuring contrasting hydrophilic and hydrophobic structures, rapid dual-temperature responsiveness was achieved through intermolecular interactions at varying temperatures. When exposed to external solvents, the original intermolecular interactions were disrupted, causing shrinkage and aggregation among polymer chains, which, in turn, modified light scattering properties. This mechanism enabled ethanol and salt stimuli-responsiveness, evident through observable color changes. The directional migration of free ions in the PPSD hydrogel endowed it with excellent sensing capabilities.