In Situ Decoding of Vitrimer Topological Evolution: A Non-Invasive, External Stress-Free Approach via Hierarchical...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Vitrimers are covalent adaptable networks (CANs) with reprocessability and self-healing properties.
• Accurate identification of the vitrimer transition temperature (Tv) is difficult due to stress- and protocol-dependent conventional methods.

Purpose of the Study:

• To develop a stress-free, in situ sensing strategy for real-time identification of vitrimer network formation and topological transitions.
• To investigate the correlation between multiscale conductive network architecture and vitrimer behavior.

Main Methods:

• Fabrication of a hierarchical sensing structure integrating a mesoscale glass fibrous web decorated with carbon nanotubes (G-CNT) and a nanoscale CNT/epoxy (EPON) percolation network.
• Utilizing piezoresistive properties of the dual-scale CNT networks to monitor electrical resistance changes during vitrimer evolution.
• Corroborating electrical signatures with differential scanning calorimetry, dynamic mechanical analysis, rheology, and dielectric analysis.

Main Results:

• The hierarchical sensing strategy enabled external-stress-free electrical tracking of vitrimer network formation and topological transitions.
• Mesoscale G-CNT networks showed higher sensitivity to topological changes, with pronounced resistance decreases at Tv (-10.9% to -20.0%).
• Nanoscale CNT/EPON networks exhibited attenuated resistance responses (-4.3% to -9.4%) related to matrix-level restructuring, confirming the structure-dynamics-signal correlation.

Conclusions:

• The developed multiscale sensing paradigm offers a scalable route for intrinsic Tv identification in vitrimer-based composites.
• This approach facilitates process-aware diagnostics for recyclable and adaptive materials.
• The findings establish a direct link between material structure, dynamic behavior, and electrical signal response.