Elasticity-gated thermal plasticity via superheating-mediated nucleation and growth in polymer networks

Living systems encode environmental history into material structure, enabling adaptive response thresholds, a capability lacking in synthetic materials with fixed thermal transitions. We present a thermodynamic approach that programs critical transition temperatures in polymer networks via salt-dependent thermal plasticity. Conditioning poly(vinyl propional) hydrogels at a swelling temperature T_s in Hofmeister-modulated media embeds thermal and saline history into equilibrium water content, which then dictates superheating-mediated nucleation upon heating. Two synergistic mechanisms: temperature-dependent miscibility encodes memory via adaptive swelling, while network elasticity gates nucleation barriers, giving T_c = T_s + ΔT, where ΔT is set by thermal history and salt identity. Structural characterization reveals a hierarchical architecture of tight physical crosslinks and loose co-evolving domains, offering a universal design rule for history-responsive materials. We demonstrate reprogrammable freeze-exposure indicators for vaccine cold-chain monitoring to quantify sub-zero breach severity and duration. This work establishes intelligent matter capable of autonomous sensing, memory, and adaptive actuation.