Highly Entangled Polymer Gels Toward Controlled Stiffness and Toughness in Soft Materials

The development of highly entangled polymer gels marks a significant advancement in the design of soft materials. Unlike conventional gels, which often suffer from an intrinsic tradeoff between stiffness and toughness, these entangled systems overcome such limitations by enabling stress dissipation through chain sliding and entropic elasticity. As a result, they exhibit exceptional mechanical robustness, high fatigue resistance, and minimal hysteresis. This review explores the structure-property-performance relationships and characterization methods associated with entangled networks, with particular emphasis on their advantages over highly chemically crosslinked gels. Key synthetic strategies, such as in situ polymerization under high monomer concentrations, spatial confinement approaches, and novel processing methods, are also discussed. Furthermore, we highlight the functional versatility and emerging applications of these polymer materials in flexible electronics, ion transport regulation, 3D printing, and environmental remediation, as well as the use of computational, simulation, and artificial intelligence/machine learning (AI/ML) approaches in studying their overall dynamic behavior. By consolidating recent advancements and identifying persisting challenges, this review aims to provide a roadmap for advancing highly entangled polymer gels toward harmonizing superior mechanical performance and multifunctional adaptability.