Activation Energies Control the Macroscopic Properties of Physically Cross-Linked Materials

• Published in: Angewandte Chemie (International ed.) Vol. 53; no. 38; pp. 10038 - 10043
• Main Authors: Appel, Eric A., Forster, Rebecca A., Koutsioubas, Alexandros, Toprakcioglu, Chris, Scherman, Oren A.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 15.09.2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Barriers; Binding; Correlation; Crosslinking; Dynamical systems; Dynamics; Hydrogels; macromolecules; nanomaterials; Self healing materials; self-healing; Strength; supramolecular polymers; macromolecules; supramolecular polymers; nanomaterials; self-healing
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201403192

Here we show the preparation of a series of water‐based physically cross‐linked polymeric materials utilizing cucurbit[8]uril (CB[8]) ternary complexes displaying a range of binding, and therefore cross‐linking, dynamics. We determined that the mechanical strength of these materials is correlated directly with a high energetic barrier for the dissociation of the CB[8] ternary complex cross‐links, whereas facile and rapid self‐healing requires a low energetic barrier to ternary complex association. The versatile CB[8] ternary complex has, therefore, proven to be a powerful asset for improving our understanding of challenging property–structure relationships in supramolecular systems and their associated influence on the bulk behavior of dynamically cross‐linked materials. Supramolecular hydrogels were obtained by utilizing the host–guest interactions of the macrocycle cucurbit[8]uril (CB[8]) with various guest molecules. The mechanical strength of these materials is directly correlated to the energetic barrier of the dissociation of the CB[8] ternary complex cross‐links, whereas the self‐healing requires a low energetic barrier for complex association.