High-performance reverse thermoresponsive hydrogel enabled by one-pot PDMS-enriched domain crosslinking.

Abstract

Reverse thermoresponsive hydrogels, which exhibit low transparency at ambient temperature and become transparent upon heating, offer distinct advantages in information encryption, thermal display, and emergency signaling. However, integrating such optical responsiveness with mechanical robustness, moisture retention, and interfacial adhesion remains a challenge. Herein, we report a highly stretchable and reverse thermoresponsive hydrogel based on polyacrylamide (PAM) crosslinked by PDMS-enriched microgel-like domains, synthesized via an emulsion-assisted one-pot strategy. During polymerization, hydrophobic PDMS chains form domain aggregates and covalently integrate with PAM at the interface, resulting in a robust and deformable domain network. The hydrogel exhibits excellent mechanical performance (5680% stretchability, 5.8 MJ m^-3 toughness) and reversibly transitions from opaque to transparent upon heating, due to entropy-driven domain reorganization that reduces interfacial light scattering. This enables rapid thermal decryption and high-contrast visual display without external energy inputs. The hydrogel also shows enhanced water retention, strong adhesion to various substrates, and sodium chloride (NaCl)-enabled strain sensing. This work provides a structurally simple yet multifunctional platform for next-generation optical encryption materials and flexible photonic devices.