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Photoresponsive Slide-Ring Gels Enable Modulation of Sliding Dynamics.
Dalila Cafagno1,2,3, Serena Silvi2, Mark W Tibbitt1
1Department of Mechanical and Process Engineering, Macromolecular Engineering Laboratory, ETH Zurich, Sonneggstrasse 3, Zurich, 8092, Switzerland.
Angewandte Chemie (International Ed. in English)
|July 8, 2025
Summary
We developed light-responsive slide-ring gels (SRGs) using azobenzene polymers. Light triggers changes in cyclodextrin sliding, reversibly altering the gel
Area of Science:
- Polymer Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- Cyclodextrin-based slide-ring gels (SRGs) exhibit unique topology with slidable cross-links, enabling energy dissipation, ductility, and toughness.
- Controlling SRG mechanical properties is crucial but largely limited to macrocycle loading.
- Stimuli-responsive SRGs remain largely unexplored.
Purpose of the Study:
- To introduce light-responsive SRGs by incorporating azobenzene-containing polymers.
- To investigate the modulation of cyclodextrin sliding dynamics via light-induced azobenzene photoswitching.
- To demonstrate reversible changes in SRG mechanical properties (stiffness/softness) through external light stimuli.
Main Methods:
- Synthesis of azobenzene-containing polymers for SRG construction.
- Utilizing UV-Vis and circular dichroism spectroscopy to study macrocycle-polymer interactions.
- Mechanical testing to evaluate the reversible changes in gel properties.
Main Results:
- Azobenzene-containing polymers successfully formed light-responsive SRGs.
- Alpha-cyclodextrins (α-CDs) bind to azobenzenes in the E configuration, restricting sliding.
- UV light induces E-to-Z isomerization of azobenzenes, releasing α-CDs and enabling free translocation, leading to reversible stiff-to-soft transitions.
Conclusions:
- Light-responsive SRGs based on azobenzene polymers were successfully developed.
- Photoswitching of azobenzenes effectively controls α-CD sliding dynamics.
- This provides a novel method for externally tuning SRG mechanical properties.
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