Mechanical Bonds Unlock Rapid Stress Relaxation in Covalent Adaptable Networks <italic style="font-style: italic">via</italic> Topology-preserving Chain Sliding

Jun Zhao; Lin Cheng; Zhao-Ming Zhang; Wei Yu; Xu-Zhou Yan

doi:10.1007/s10118-026-3735-1

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Mechanical Bonds Unlock Rapid Stress Relaxation in Covalent Adaptable Networks via Topology-preserving Chain Sliding

Special Topic: Distinguished Young Scholars in Polymer Science | Updated：2026-07-01

- Mechanical Bonds Unlock Rapid Stress Relaxation in Covalent Adaptable Networks via Topology-preserving Chain Sliding
- Chinese Journal of Polymer Science Vol. 44, Issue 7, Pages: 2051-2061(2026)
- Affiliations：
  
  a.Renji Branch of National Center for Translational Medicine, Shanghai Key Laboratory for Nucleic Acid Chemistry and Nanomedicine, Renji Hospital, and School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
  b.State Key Laboratory of Synergistic Chem-Bio Synthesis, Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Author bio：
  
  lincheng@sjtu.edu.cn (L.C.)
  xzyan@sjtu.edu.cn (X.Z.Y.)
- Funds：
- DOI：10.1007/s10118-026-3735-1
  CLC：
- Received：23 February 2026，
  
  Accepted：05 May 2026，
  
  Online First：11 June 2026，
  
  Published：05 July 2026
- Accepted：
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Zhao, J.; Cheng, L.; Zhang, Z. M.; Yu, W.; Yan, X. Z. Mechanical bonds unlock rapid stress relaxation in covalent adaptable networks via topology-preserving chain sliding. Chinese J. Polym. Sci. 2026, 44, 2051–2061

Jun Zhao, Lin Cheng, Zhao-Ming Zhang, et al. Mechanical Bonds Unlock Rapid Stress Relaxation in Covalent Adaptable Networks via Topology-preserving Chain Sliding[J]. Chinese Journal of Polymer Science, 2026, 44(7): 2051-2061. DOI: 10.1007/s10118-026-3735-1.
Zhao, J.; Cheng, L.; Zhang, Z. M.; Yu, W.; Yan, X. Z. Mechanical bonds unlock rapid stress relaxation in covalent adaptable networks via topology-preserving chain sliding. Chinese J. Polym. Sci. 2026, 44, 2051–2061 DOI： 10.1007/s10118-026-3735-1.

Jun Zhao, Lin Cheng, Zhao-Ming Zhang, et al. Mechanical Bonds Unlock Rapid Stress Relaxation in Covalent Adaptable Networks via Topology-preserving Chain Sliding[J]. Chinese Journal of Polymer Science, 2026, 44(7): 2051-2061. DOI: 10.1007/s10118-026-3735-1. DOI：

摘要

In dual-dynamic mechanically interlocked vitrimers (MIVs)

slidable mechanically bonded cross-links enable topology-preserving chain sliding

which accelerates dynamic covalent bond (DCB) exchange

as evidenced by the lower activation energy for vinylogous urethane dissociation relative to analogous covalent adaptable networks with fixed cross-links. This synergy between the mechanical bonds and DCBs boosted the rapid stress relaxation in MIVs.

Abstract

Covalent adaptable networks (CANs) have emerged as versatile platforms for sustainable polymer materials

where precise control over the dissociation/exchange kinetics of dynamic covalent bonds is essential for tuning their viscoelastic behaviors. Herein

we introduce a topology-preserving strategy to accelerate network relaxation by

embedding slidable mechanically interlocked cross-links into vinylogous urethane-based CANs

yielding mechanically interlocked vitrimers (MIVs). The mechanically bonded junctions are constructed by incorporating kinetically stable acetoacetate-functionalized [2

]

pseudorotaxane cross-linkers through catalyst-free polymerization with diamines. Although exhibiting higher glass-transition temperatures than a control network with identical cross-linking density but fixed cross-links

the representative MIV-

maintains comparable ductility while displaying greater toughness

indicating that the slidable cross-links effectively enhance chain sliding. At elevated temperatures

this chain sliding prominently accelerates stress relaxation in MIV-

showing a substantial reduction in the apparent activation energy for vinylogous urethane exchange compared with the control (10.3 versus 21.2 kJ/mol). Unlike the control with fixed cross-links

the chain motion enabled by mechanical bonds enhances the diffusion of dynamic covalent moieties

thereby effectively promoting bond exchange throughout the network. Owing to the associative nature of vinylogous urethane exchange

the mechanically bonded cross-links remain topologically constrained on the polymer chains during relaxation. Consequently

the accelerated stress relaxation originates from mechanical-bond-mediated chain sliding rather than defect generation

clearly distinguishing MIVs from defect-mediated dual-dynamic CANs designs commonly employed to promote relaxation. These results disclose how the mechanically interlocked structures regulate chemical reactions in cross-linked polymer networks

establishing a novel strategy of topology-engineering guided structural design for smart multidynamic polymers.

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Mechanical Bonds Unlock Rapid Stress Relaxation in Covalent Adaptable Networks via Topology-preserving Chain Sliding

DOI：10.1007/s10118-026-3735-1

摘要

Abstract

关键词

Keywords

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