Theoretical studies on anhydride dynamic covalent bond exchange mechanisms

Theoretical studies on anhydride dynamic covalent bond exchange mechanisms

Communications Chemistry

10.1038/s42004-025-01736-3

https://doi.org/10.1038/s42004-025-01736-3

Xinglong Zhang, Qiubo Chen, Nannan Li, Michael B. Sullivan, Jianwei Zheng

reaction mechanism, Dynamic covalent polymers, anhydrides

17 November 2025

Zhang, X., Chen, Q., Li, N., Sullivan, M. B., Zheng, J.W. (2025). Theoretical studies on anhydride dynamic covalent bond exchange mechanisms. Communications Chemistry, 8(1). https://doi.org/10.1038/s42004-025-01736-3

Abstract Anhydrides have been utilised to synthesize covalent adaptable networks (CANs), enabling the recycling of thermosets and immiscible plastic wastes due to their dynamic bond exchange properties. However, the exact bond exchange mechanism involving anhydrides remains unclear. Herein, we identify the bond exchange mechanism behind anhydride-based CANs through a comprehensive study of the anhydride bond exchange mechanism under uncatalysed and acid-catalysed reaction conditions using density functional theory (DFT) methods. Careful conformational samplings of structures and transition states have been performed to ensure accurate determination of the key rate-determining step. The bond exchange barrier increases from 44.1 kcal/mol at 25 °C to 52.8 kcal/mol at 200 °C for the uncatalysed route and from 25.9 kcal/mol to 33.0 kcal/mol over the same temperature range for acid-catalysed route. Our results implicate that anhydrides can be good dynamic covalent bond linker candidates in CANs for high temperature applications and acid catalysts may be used as mediators to assist low-temperature reprocessing and recycling.

Attribution 4.0 International (CC BY 4.0)

This research / project is supported by the A*STAR - RIE2025 Manufacturing, Trade and Connectivity (MTC) Programmatic Fund (M22K9b0049)
Grant Reference no. : M22K9b0049

This research / project is supported by the A*STAR - Career Development Fund
Grant Reference no. : C210812008

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