Thermally Driven Polymorphic Transition Prompting a Naked‐Eye‐Detectable Bending and Straightening Motion of Single Crystals |
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Authors: | Tatsuya Shima Dr Takahiro Muraoka Dr Norihisa Hoshino Prof Tomoyuki Akutagawa Dr Yuka Kobayashi Prof Kazushi Kinbara |
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Institution: | 1. Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2‐1‐1, Katahira, Aoba‐ku, Sendai 980‐8577 (Japan) http://www.tagen.tohoku.ac.jp/labo/kinbara/index.html;2. Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, 4‐1‐8, Honcho, Kawaguchi, Saitama 332‐0012 (Japan);3. Advanced Key Technologies Division, National Institute for Materials Science, 1‐2‐1 Sengen, Tsukuba, Ibaraki 305‐0047 (Japan) |
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Abstract: | The amplification of molecular motions so that they can be detected by the naked eye (107‐fold amplification from the ångström to the millimeter scale) is a challenging issue in the development of mechanical molecular devices. In this context, the perfectly ordered molecular alignment of the crystalline phase has advantages, as demonstrated by the macroscale mechanical motions of single crystals upon the photochemical transformation of molecules. In the course of our studies on thermoresponsive amphiphiles containing tetra(ethylene glycol) (TEG) moieties, we serendipitously found that thermal conformational changes of TEG units trigger a single‐crystal‐to‐single‐crystal polymorphic phase transition. The single crystal of the amphiphile undergoes bending and straightening motion during both heating and cooling processes at the phase‐transition temperatures. Thus, the thermally triggered conformational change of PEG units may have the advantage of inducing mechanical motion in bulk materials. |
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Keywords: | amphiphiles conformational change macrocycles polymorphism thermal responsiveness |
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