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Self-Healing Behavior in a Thermo-Mechanically Responsive Cocrystal during a Reversible Phase Transition
Guangfeng Liu1, Jie Liu2, Xin Ye2
1School of Materials Science and Engineering, Nanyang Technological University Singapore, 639798, Singapore, Singapore.
Angewandte Chemie (International Ed. in English)
|December 9, 2016
Summary
Molecular motions in coronene-based supramolecular rotators are amplified to macroscopic crystal changes. These cocrystals exhibit self-healing and dynamic thermo-mechanical responses during reversible phase transitions.
Area of Science:
- Supramolecular chemistry
- Materials science
- Crystallography
Background:
- Coronene and 1,2,4,5-tetracyanobenzene (TCNB) can form charge-transfer complexes.
- Supramolecular rotators offer potential for novel material properties.
- Understanding molecular motion amplification is key to designing advanced materials.
Purpose of the Study:
- To investigate the co-assembly of coronene and TCNB into charge-transfer cocrystals.
- To explore the self-healing and thermo-mechanical properties of these cocrystals.
- To elucidate the mechanism behind thermally-induced single-crystal-to-single-crystal (SCSC) phase transitions.
Main Methods:
- Co-crystallization of coronene and TCNB.
- Microscopic observation of crystal behavior.
- Differential scanning calorimetry (DSC) for thermal analysis.
- X-ray crystallography to determine structural changes.
Main Results:
- Formation of coronene-TCNB cocrystals with amplified molecular motions.
- Observation of remarkable self-healing behavior and thermo-mechanical responses.
- Identification of a thermally-reduced-rate-dependent dynamic character in SCSC phase transitions.
- Crystallographic analysis revealed global packing similarity with local differences driving self-healing.
Conclusions:
- The co-assembly of coronene and TCNB leads to macroscopic crystal changes from molecular-level motions.
- The cocrystals demonstrate significant self-healing and dynamic responses linked to SCSC phase transitions.
- The structural similarities and differences between phases are crucial for the observed self-healing properties.
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