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Issue 36, 2016
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Chiral 5-phenylpyrimidine liquid crystals with ‘de Vries-like’ properties: dependence of electroclinic effect and ferroelectric properties on carbosilane nanosegregation

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Abstract

A homologous series of tri-, di- and monocarbosilane mesogens with a 5-phenylpyrimidine core and a chiral (S,S)-2,3-difluorohexyloxy chain were synthesized and characterized. We show that shortening the carbosilane end-group has a detrimental effect on ‘de Vries-like’ properties, causing an increase in reduction factor R from 0.17 for the tricarbosilane QL32-6 to 0.38 for the monocarbosilane QL34-6, both at the point of maximum layer contraction upon transition from the orthogonal SmA* to the tilted SmC* phase. This increase in R correlates with an increase in birefringence Δn, a broadening in the SmA* temperature range and a decrease in optical tilt angle θopt in the SmC* phase, which are all consistent with an increase in orientational order and a decrease in lamellar order. The electroclinic effect (ECE) in the SmA* phase decreases with decreasing length of the carbosilane end-group, which is consistent with previous observations of high ECE in ‘de Vries-like’ liquid crystals. On the other hand, spontaneous polarization PS measurements suggest that polar ordering in the SmC* phase is not strongly dependent on R.

Graphical abstract: Chiral 5-phenylpyrimidine liquid crystals with ‘de Vries-like’ properties: dependence of electroclinic effect and ferroelectric properties on carbosilane nanosegregation

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Supplementary files

Article information


Submitted
22 Jul 2016
Accepted
19 Aug 2016
First published
19 Aug 2016

J. Mater. Chem. C, 2016,4, 8483-8489
Article type
Paper

Chiral 5-phenylpyrimidine liquid crystals with ‘de Vries-like’ properties: dependence of electroclinic effect and ferroelectric properties on carbosilane nanosegregation

C. P. J. Schubert, C. Müller, F. Giesselmann and R. P. Lemieux, J. Mater. Chem. C, 2016, 4, 8483
DOI: 10.1039/C6TC03120J

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