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Adjusting Local Molecular Environment for Giant Ambient Thermal Contraction
Xingyuan Shen1,2, Timothy Connolly3, Yuhui Huang1
1State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China.
Macromolecular Rapid Communications
|May 19, 2016
Summary
Researchers developed a low-energy triggered switch using S-dibenzocyclooctadiene (DBCOD) polymers. These polymers exhibit significant negative thermal expansion (NTE) upon near-infrared irradiation, offering advanced material applications.
Area of Science:
- Materials Science
- Polymer Chemistry
- Nanotechnology
Background:
- Developing low-energy triggered switches with mechanoresponse capabilities is crucial for advanced technological applications.
- Submolecular moieties capable of conformational changes under external stimuli are of significant interest.
Purpose of the Study:
- To investigate the mechanoresponse of S-dibenzocyclooctadiene (DBCOD)-based polymers.
- To explore the potential of DBCOD for creating materials with tunable negative thermal expansion (NTE).
Main Methods:
- Utilized near-infrared (NIR) irradiation as a low-energy stimulus.
- Employed experimental evidence and theoretical calculations to analyze conformational changes.
- Investigated the effect of molecular asymmetry on polymer crystallinity and conformational kinetics.
Main Results:
- S-dibenzocyclooctadiene (DBCOD) undergoes a conformational change from twist-boat to chair upon NIR irradiation, inducing thermal contraction.
- Introducing molecular asymmetry significantly reduces crystallinity, enhancing the kinetics of the conformational change.
- Achieved tunable negative thermal expansion (NTE) coefficients ranging from -1140 to -2350 ppm K⁻¹.
Conclusions:
- DBCOD-based polymers demonstrate a highly efficient and tunable NTE effect.
- The observed NTE coefficient of -2350 ppm K⁻¹ is approximately ten times superior to existing systems.
- These findings highlight the potential of DBCOD for developing next-generation smart materials.
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