Breaking the stiffness-dynamicity trade-off in polymer gels via a switchable hydrogen-bond clustering strategy

Polymer gels are fundamentally constrained by an inherent trade-off between mechanical stiffness and dynamicity, impeding the synergistic integration of high strength with adaptive functionalities such as self-healing, recyclability, and reconfigurability. Here, we present a strategy to resolve this long-standing challenge by engineering switchable hydrogen-bond clustering (HC) within a deep eutectic solvent-based adhesive gel. Precise modulation of water content triggers the reversible transition between a rigid state (elastic modulus ∼45 MPa) and a highly dynamic state (modulus reduction by 10⁵-fold). This on-demand switching capability facilitates direct 3D printing, efficient recycling assisted by trace water, and autonomous self-healing (∼83% recovery efficiency). Crucially, the gel retains both high stiffness and robust interfacial adhesion after turning on the HC. The HC switchable strategy establishes a versatile design principle for fabricating strong, yet dynamically reconfigurable polymeric networks, with promising implications for advanced wearables, soft robotics, and adaptive adhesive technologies.