From Crosslinking to Interlocked Structures: Advancing Mechanical Properties in Polymer Networks

Polymer networks are essential for applications requiring durability and flexibility, but traditional covalent crosslinking often leads to brittle materials due to structural inhomogeneities. Doubly threaded slide-ring gels (dt-SRGs) have emerged as a solution by combining covalent bonds with mechanically interlocked crosslinks, enhancing mobility, toughness, and stress dissipation through sliding and rotation of ring structures. However, the microscopic dynamics behind these properties are not well understood. This study uses coarse-grained molecular dynamics simulations to investigate the structure-property relationships of dt-SRGs. By systematically replacing fractions of covalent crosslinks with doubly threaded slide-ring and applying uniaxial deformation, we assess the effects of ring size, mobility, and fraction on mechanical properties. Our simulations indicate that dt-SRGs are softer and more stretchable than traditional covalent networks at the same crosslink density, with rings acting as effective crosslinkers that enables stress redistribution through sliding; increasing the ring fraction reduces the modulus and enhances network stretchability. Additionally, we explore networks with supramolecularly templated entanglements, which form topologically defined structures that improve modulus and swelling behavior. Comparing these with dt-SRG models deepens our understanding of how different interlocked structures influence polymer network performance. Our findings demonstrate that dt-SRGs offer a promising alternative to traditional covalent networks by combining flexibility and toughness, making them valuable for applications with critically enhanced mechanical properties.