Stiffness Reinforcement in Polymer Networks Through Supramolecular Topological Linking.

Polymer networks possess numerous elastically defective and isolated loops, which do not contribute to mechanical stiffness. In this report, we introduce a strategy of supramolecular topological linking to access stiffer-yet-ductile polymeric materials through incorporation of supramolecular tetravalent crosslinkers. Dynamic dissociation/re-association between these high-functionality crosslinks enables the formation of topologically-linked loops that serve as elastic springs to stiffen the networks. An exceptional scaling exponent of 2.05 for Young's modulus versus crosslinker concentration is obtained, exceeding most reported randomly-crosslinked polymeric systems. Compared to conventional analogs, the mechanical properties of the resultant materials are enhanced: Young's modulus (2-fold), elongation at break (8-fold), and work of fracture (100-fold). Uplifting modulus scalings through supramolecular topological linking paves a new path to the design of stiffness-reinforced soft materials, holding substantial promise in load-bearing application scenarios such as tissue implants, bioelectronic interfaces, and soft robotics.