Mechanically Interlocked Vitrimer Based on Polybenzoxazine and Polyrotaxane

Abstract

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-acetaltype 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.

Enhancement of the mechanical properties of organic–inorganic hybrid elastomers by introducing movable and reversible crosslinks

“…The Young's modulus decreased according to a general correlation between Young's modulus and toughness. 49 Based on rotaxane structures, slide and movable crosslinks have been reported for carbon- 50–56 and PDMS-based 42 materials, suggesting probable movable crosslinks involving γCDs in organic–inorganic hybrid materials.…”

Solvent-free preparation of imine vitrimers: leveraging benzoxazine crosslinking for melt processability and tunable mechanical performance

“…Interestingly, both propylene oxide based p(iBOX) networks underwent signicant mass loss in both THF and CHCl 3 , which suggested that swelling mediated bond exchange occurred, permitting the formation of loops and other soluble network fragments which effectively reduced the gel fraction. 9,55 The p(MXDA-iBOX) network demonstrated the best solvent resistance, with mass change remaining below 2% in all tested solvents.…”

“…51 This work was extended to prepare a series of bio-derived BOX vitrimers based on internally-catalyzed transesterication reactions between backbone ester bonds and pendant hydroxyl groups. [52][53][54] Following these initial reports of BOX-derived vitrimers, the eld has grown rapidly to incorporate alternative dynamic chemistries including transacetalation, 55,56 transcarboamoylation, 57 and boronic ester exchanges. 58 Several studies have reported the incorporation of imine bonds into BOX to impart unique properties such as shape memory, 59 liquid crystalline behavior, 60 and nitrogen doping upon pyrolysis.…”

Environmentally Friendly Sustainable Thermoset Vitrimer-Containing Polyrotaxane

“…The mechanical properties of this material, such as its ductility and tensile strength, were relatively better than those of polybenzoxazine (PBz) vitrimers prepared without an MIV by dynamic transacetal exchange. The authors also demonstrated that the PBz MIV underwent faster dynamic bond exchange and had a lower activation energy and that dynamic bond exchange was facilitated by the mobile intramolecular motion of PR . However, in both of these studies, the properties of the resultant materials were not significantly improved, and the effects of PR on multiple properties of the thermoset vitrimers, such as their toughness, self-healing, shape memory, chemical degradability, and seawater biodegradability, were not reported.…”

“…Furthermore, the intramolecular motion of rotaxane promoted the dynamic exchange of vinylogous urethane bonds by loosening the network. In 2023, Zhu et al reported an MIV based on benzoxazine monomers and cyclodextrin-type PRs. The mechanical properties of this material, such as its ductility and tensile strength, were relatively better than those of polybenzoxazine (PBz) vitrimers prepared without an MIV by dynamic transacetal exchange.…”