Thermoresponsive Hydrogel with Thermal Memory

Thermal plasticity—the capacity to dynamically reconfigure material properties in response to thermal history—is a hallmark of biological systems that remains elusive in synthetic hydrogels. Inspired by coral symbiont acclimatization, thermally plastic hydrogels (TP‐gels) based on polyvinyl butyral are reported, which emulate biological thermal memory through a bioinspired feedback loop: thermoresponsive equilibrium swelling encodes thermal history, while elastic network constraints translate this memory into programmable phase transition thresholds ( T c ). By exploiting temperature‐dependent polymer‐water miscibility, TP‐gels achieve multi‐stable states through adaptive swelling, enabling reversible opacity transitions with T c shifts of 3–7 °C per thermal training cycle. Crucially, elasticity‐mediated suppression of spinodal decomposition stabilizes metastable states during thermal encoding, preventing premature phase separation. This plasticity is leveraged for cryptographic applications, demonstrating sequential information decryption via thermal trajectory programming—where spatially resolved T c gradients serve as thermodynamic keys. This work establishes a paradigm for materials with embodied environmental intelligence, bridging the divide between biological adaptability and synthetic systems through thermodynamic metastability engineering.