Distinguishing relaxation dynamics in transiently crosslinked polymeric networks

Polymeric materials based on reversible non-covalent associations possess diverse mechanical behaviour, responsiveness to external stimuli and self-healing properties. Unlike covalently-bonded polymeric materials, whose properties are conventionally engineered through the polymer structure alone, the mechanical performance of a supramolecular material can be designed via two motifs: the polymer architecture (e.g., polymer molecular weight or structure) and the physical crosslinks (e.g., thermodynamics or kinetics of binding) between polymers. Here, we demonstrate the preparation of aqueous-based supramolecular polymeric materials utilising cucurbit[8] uril (CB[8]) crosslinking of multivalent polymers of varying molecular weights. By exploiting three kinetically distinct supramolecular motifs, we show that it is possible to relate the contributions of polymer architecture and dynamic crosslinking to the ultimate mechanical properties of the materials. These studies improve our understanding of the challenging relationships between design of supramolecular polymeric materials and their complex viscoelastic behaviour as well as relaxation dynamics.