CO₂ -Strengthened Double-Cross-Linked Polymer Gels from Frustrated Lewis Pair Networks

Conventional thermosets consisting of polymer networks with robust and irreversible chemical linkages are incapable of reshaping or reprocessing once formed. In contrast, reversible non-covalent crosslinks can impart structurally flexible and reconfigurable feature to the networks, but at the expense of certain mechanical strength. The integration of fixed covalent bonds and noncovalent bonds into these materials can usually attain enhanced mechanical properties and meanwhile provide dynamic and adaptable functions, such as responsive and healing ability to external stimuli. Here a double-cross-linked frustrated Lewis pair network (FLPN) is developed through a specific three-component reaction among triarylborane, triarylphosphine, and CO₂ , which is composed of permanent chemical crosslinks and dynamic CO₂ gas-bridged connections. The amount of CO₂ added can regulate the density of supramolecular node in such FLPN, so as to control the strength and toughness of the gel material. Moreover, the broken gel can be rapidly healed by CO₂ stimulus through the reconstruction of dynamic covalent network. This study will inspire a new way to create gas-based smart materials by incorporating frustrated Lewis pair chemistry into traditional gel system.