Mechano-nanoconfinement synergy constructs layered rigid-soft interlocked architecture for ultra-strong and resilient hydrogels

Achieving concurrent enhancement of strength, toughness, and resilience in hydrogels remains a significant challenge, particularly for applications in harsh environments. A “mechano-nanoconfinement synergy” strategy is proposed to fabricate poly (vinyl alcohol)/hydroxyapatite (PVA/HAp) nanocomposite hydrogels, featuring an alternating “rigid-soft” interlocked architecture. This approach leverages the particular temperature-induced transitions from viscoelastoplastic to viscoelastic states, which enables the mechanical incorporation of very high-loading HAp reinforcements within the viscoelastoplastic hydrogel, followed by structural stabilization via freezing-induced viscoelasticity. Quasi-static cold compression is further applied to promote local structural alignment and densification, driven by the cooperative roles of mechanical force, nanoconfinement from high-content HAp, and enhanced polymer mobility facilitated by a high-humidity thawing. The resulting rigid HAp-rich layers, characterized by dense packing and local aligned nanorods, alternate with soft PVA-rich layers, collectively imparting synergistic combination of a rigid load-bearing framework, entropy-driven recovery force, crack suppression, and abundant sacrificial bonds. Consequently, the layered hydrogels represent simultaneous improvements in multiple mechanical properties: exceptional compressive strength (31.94 MPa), outstanding resilience (95.41% recovery at 80% strain), and remarkable toughness (6.91 MJ m −3 ). Furthermore, the dense, layered architecture endows the hydrogel with high resistance to swelling, dehydration, freezing, and puncture. These comprehensive properties enable the hydrogel to effectively address the differentiated requirements of structural stability for marine sensing and bioactive mechanical support for bone repair.