Folding fluorescent probes for self-reporting transesterification in dynamic polymer networks.

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Macroscopic mechanical methods struggle to directly probe dynamic bond exchange in covalent adaptable networks (CANs).
• Understanding dynamic bond exchange is crucial for designing materials with tunable properties.

Purpose of the Study:

• To develop a fluorescent strategy for directly reporting dynamic bond exchange in transesterification-based CANs.
• To utilize folding molecular probes for real-time monitoring of chemical reactions within polymer networks.

Main Methods:

• Synthesis of perylene diimide (PDI)-dimer probes with dynamic ester spacers.
• Incorporation of PDI-dimers into crosslinked thiol-Michael networks (TMN) and poly(4-hydroxybutyl acrylate) networks (PHBA).
• Monitoring fluorescence changes (color shift from orange to yellow) corresponding to transesterification and bond dynamics.

Main Results:

• PDI-dimers exhibit a distinct color change from orange to yellow upon dynamic bond exchange in CANs.
• The fluorescent strategy successfully visualized stress relaxation and self-stiffening in TMN and PHBA networks.
• The method provides quantitative information with spatiotemporal resolution.

Conclusions:

• The fluorescent probe offers a direct and visual method to study dynamic bond exchange in CANs.
• This approach enables the real-time monitoring of chemical transformations and mechanical behaviors in crosslinked materials.
• The strategy has broad applicability for investigating dynamic chain exchange mechanisms in various polymer systems.