Control of Intramolecular Hydrogen Bonding in a Conformation-Switchable Helical-Spring Polymer by Solvent and Temperature |
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| Authors: | Dr Young-Jae Jin Prof Toshiki Aoki Prof Giseop Kwak |
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| Institution: | 1. Department of Polymer Science & Engineering, Polymeric Nanomaterials Laboratory, School of Applied Chemical Engineering, Kyungpook National University, 1370 Sankyuk-dong, Buk-ku, Daegu, 702-701 Korea;2. Department of Chemistry and Chemical Engineering, Graduate School of Science and Technology, Center for Transdisciplinary Research, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata, 950-2181 Japan |
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| Abstract: | A substituted poly(phenylacetylene) derivative (PPAHB) with two hydroxymethyl groups at the meta position of the side phenyl ring was examined as a conformation-switchable helical spring polymer that responds to solvent and heat stimuli in a precisely controlled manner. Intramolecular hydrogen bonds, which cause the helical structure of the polymer, were broken and re-formed by adjusting the hydrogen-bonding strength values (pKHB) of various combinations of solvents or by varying the temperature. In this process, a reversible conformational change from cis–cisoid to cis–transoid, accompanied by a phase transition in the form of a helix-coil transformation occurred, with the polymer exhibiting critical changes of color fading and recovery in specific environments. These results demonstrate that PPAHB can be used as either a pKHB indicator or a thermometer. The color changes of the polymer solution are described in detail based on spectroscopic analyses and thermodynamic considerations. |
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| Keywords: | Helikale Federn Konformationsänderungen Phasenumwandlungen Poly(phenylacetylen) Wasserstoffbrücken |
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