Mechanically Interlocked Vitrimer Based on Polybenzoxazine and Polyrotaxane

A mechanically interlocked vitrimer (MIV) based on a benzoxazine monomer and polyrotaxane (PR) has been prepared through a mechanically interlocked network (MIN) and dynamic covalent bond chemistry. The dynamic transacetalation exchange through the N,O-acetal-type polybenzoxazine (PBz) structure was catalyzed by a tin compound. Compared to the controlled PBz vitrimer without a MIN, the designed PBz MIV shows enhanced mechanical performance including ductility and tensile strength while maintaining relatively high Young’s modulus and glass transition temperature ( T g ). The PBz MIV can be reprocessed several times without compromising mechanical performance and thermal stability. The PBz MIV also exhibits a faster dynamic bond exchange and a lower activation energy compared to the controlled PBz vitrimer due to the mobile intramolecular motions of PR in the network allowing for a dynamic bond exchange in the MIV more readily. The usefulness of the present study for the preparation of high-performance eco-friendly thermosetting vitrimers is discussed.