Highly stretchable covalent adaptive networks enabled by dynamic boronic diester linkages with nitrogen→boron coordination

Abstract

AbstractCovalent adaptive networks (CANs), which can be topologically rearranged, are of remarkable versatility. Here, the collaboration of dynamic boronic diester linkages with nitrogen→boron coordination was used to develop catalyst‐free, highly stretchable CANs. The CANs with different cross‐link densities were prepared via one‐pot synthesis of poly(propylene glycol) diglycidyl ether, 3‐amino‐1,2‐propanediol and benzene‐1,4‐diboronic acid. They were found thermorheologically simple, of which the linear viscoelasticity obeyed the principle of time–temperature superposition. Their topological rearrangements activated by the reshuffling of dynamic linkages was slowed down, while the activation energy on complex viscosity decreased with increasing the cross‐link density. The CANs demonstrated great stretchability, malleability and self‐healing ability, which could be stretched to 15,000× its original length with no break at a strain rate up to 33.3 min−1. Furthermore, the reshuffling of dynamic linkages contributed to efficient energy dissipation with a maximum efficiency of 91% at room temperature.