Supramolecular polymer networks crosslinked by crown ether-based host-guest recognition: dynamic materials with tailored mechanical properties in the bulk

Supramolecular polymer networks (SPNs) based on host-guest recognition have attracted much research attention in the development of smart supramolecular materials. However, research studies have mainly focused on SPNs in solution or in the gel state, but SPNs in bulk which are also crucial for the development of supramolecular materials are rarely explored. Herein, we report a series of SPNs where a polynorbornene derivative is crosslinked through crown ether-based host-guest recognition to form an effective network which endows the corresponding materials in the bulk with tough characteristics and various dynamic behaviors. In particular, benefiting from the role of host-guest recognition as a sacrificial bond, the representative SPN exhibits notable strength, ductility, as well as high toughness. The lifetime and apparent activation energy of the network are 0.015 s and 80.1 kJ mol(-1), respectively, which represents the structural basis of SPNs to achieve their mechanical properties. Furthermore, the SPNs could respond to the stimulus of pH, and are also able to self-heal and even reprocess to extend the lifetime of the materials. These findings are beneficial for deepening the understanding of SPNs in bulk and would promote the development of supramolecular materials with emergent functions and applications.