Abstract
Octaphenylcyclotetrasiloxane (OPCTS) was investigated by Keyes and Daniels [1], who concluded that this compound presents a plastic phase in the range between 188°C and 205°C during the heating process and before the transition to the isotropic liquid phases. They used differential thermal analysis to observe the appearance of this mesophase and of a solid-solid phase transition at %76°C. During the reverse process a supercooling effect was observed: the mesophase exists from 203°C to 155°C. The arguments in favour of the plastic crystal nature of the mesophase were the assumed globular shape of the molecule and the observed optical isotropy, which seemed to exclude a liquid crystal nature of the mesophase. In fact liquid crystals are in-general characterized by optical birefringence and by either rod-like or disc-like molecular shapes.
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References
P.H.KEYES, W.B.DANIELS, J. Chem. Phys. 62, 5 (1975)
F.VOLINO, A.J.DIANOUX, Ann. Phys. 3, 151 (1978)
D.BRAGA, G.ZANOTTI, Acta Cryst. B36, (1980)
B.DUBINI, S.MELONE, M.G.PONZI BOSSI, F.RUSTICHELLI, submitted for publication in the proceeding of the 3.rd Liquid Crystal Conference of Socialist Countries — Budapest — August 1979
G.ALBERTINI, B.DUBINI, S.MELONE, M.G.PONZI BOSSI, F.RUSTICHELLI, G.TORQUATI J. Physique C3, 384 (1979)
G.ALBERTINI, B.DUBINI, S.MELONE, M.G.PONZI BOSSI, P.PULITI, F.RUSTICHELLI submitted to “II Nuovo Cimento”
A.LEADBETTER — private communication
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S.C. GREER, L. MEYER J. Chem. Phys. 51, 10 (1969)
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© 1980 Springer-Verlag Berlin Heidelberg
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Albertini, G., Dubini, B., Melone, S., Rustichelli, F., Torquati, G. (1980). X-Ray Diffraction Study of the Mesophase of Octaphenylcyclotetrasiloxane. In: Helfrich, W., Heppke, G. (eds) Liquid Crystals of One- and Two-Dimensional Order. Springer Series in Chemical Physics, vol 11. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-67848-6_10
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DOI: https://doi.org/10.1007/978-3-642-67848-6_10
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