Self‐Reinforced Hydrogel via Alcohol–Water Exchange: Tunable Modulus, High Impact Resistance, Recyclability, and Triple Information Encryption

Abstract Conventional hydrogels suffer from static mechanical properties, environmental fragility, and functional singularity, limiting their adaptability in flexible electronics and biological interfaces. Herein, an innovative “alcohol–water exchange” strategy is proposed to fabricate a self‐reinforced Poly (vinyl alcohol)‐ polyacrylic acid‐ Silk fibroin@1,2‐propylene glycol (VAS@1,2‐PG) hydrogel via entropy‐driven chain aggregation and nanodomain crystallization triggered by the solvent exchange of 1,2‐PG. This approach achieves dynamic modulus tuning (53.3‐fold increase to 1.28 MPa), precisely matching regional skin moduli (forearm: 457 kPa; calf: 680 kPa; face: 909 kPa). The dual physical crosslinking (nanocrystalline domains and multivalent H‐bonds) endows the hydrogel with exceptional toughness (fracture energy: 14,650.8 J m − 2 ), puncture resistance, and load‐bearing capacity (7500× self‐weight). Simultaneously, 1,2‐PG acts as a cryoprotectant, enabling frost resistance at −50 °C. The hydrogel exhibits fully reversible modulus switching (>90% recovery over 12 h cycles) and closed‐loop recyclability (strength retention: 0.23 MPa). Leveraging 1,2‐PG's reducibility and stimuli‐responsiveness, a triple‐modal (Time/Temperature/UV) information encryption system with “burn‐after‐reading” functionality is pioneered. This work establishes a solvent‐exchange‐physicochemical synergy paradigm, addressing the long‐standing trade‐off between mechanical adaptability, environmental robustness, and intelligent responsiveness for next‐generation bioelectronics and secure devices.