First observation of a smectic A-cholesteric phase transition in a thermotropic liquid crystal consisting of a rigid-rod helical polysilane |
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| Authors: | Kento Okoshi Anubhav Saxena Masanobu Naito Goro Suzaki Masatoshi Tokita Junji Watanabe Michiya Fujiki |
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| Institution: |
a Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan
b CREST-JST (Japan Science and Technology Corporation), 4-1-8 Hon-cho, Kawaguchi, Saitama 332-0012, Japan
c Department of Polymer Chemistry, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552, Japan |
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| Abstract: | A smectic A-cholesteric phase transition for a rigid-rod helical polymer, polyn-decyl-(S)-2-methylbutylsilane] (PD2MBS), with a narrow molecular weight distribution, has been observed for the first time. Polarizing optical microscopy showed that the fan-shaped texture of the smectic A phase turned into the characteristic planar texture of the cholesteric phase upon heating. The positive CD band, which corresponds to the reflection band of the cholesteric phase, gradually decreased in intensity within a range 30°C below the transition temperature on cooling, while the peak maximum shifted towards shorter wavelengths. It was concluded that the system has a very wide temperature region over which the cholesteric-smectic A phase transition occurs and in which the cholesteric pitch varies with temperature. |
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