Hysteresis-Free Near-Ideal Elastic Gels.

Abstract

The mechanical properties of covalently crosslinked gels or elastomers stem from the crosslinking of the polymer chains and entanglement. Increasing the crosslinking density of covalent networks improves their entropic elasticity but also increases their brittleness. Addressing conflicts between rigidity and toughness, large strains, elasticity, and crack extension presents a challenging task. Here, we present a spatial crosslinking (SC) strategy utilizing a spider-like crosslinker to materialize creep-resistant, and low-hysteresis hydrogels under substantial deformations (ε = 6000%). The SC approach not only boosts the entropic elasticity of the hydrogels but also disperses stress arising from fractured polymers, leading to notable enhancements in fracture strain, toughness, and crack propagation strain (8200%). Furthermore, the SC hydrogels exhibit the remarkable ability to endure 99% of the ultimate compressive strain at the fully swollen state, along with rapid rebound and creep-free capabilities, rendering them highly promising candidates for various applications such as drift-free sensor, artificial blood vessels, and soft robotics.