Odd-even effects in liquid crystals

In this paper, odd-even effects in liquid crystals are briefly summarised. Based on the position and type of the repeating units, odd-even effects can be caused by methylene (CH 2 ) k units either when terminating the LC molecules or separating monomers in dimers or polymers, or by the parity of the...

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Bibliographic Details
Published inLiquid crystals Vol. 49; no. 7-9; pp. 1010 - 1019
Main Author Jakli, Antal
Format Journal Article
LanguageEnglish
Published Abingdon Taylor & Francis 15.07.2022
Taylor & Francis Ltd
Subjects
Antiferroelectricity
Birefringence
Crystals
Elastic properties
Entropy
Liquid crystals
Methylene
molecules
odd-even effects
phase transitions
Polymers
Transition temperatures
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Summary:In this paper, odd-even effects in liquid crystals are briefly summarised. Based on the position and type of the repeating units, odd-even effects can be caused by methylene (CH 2 ) k units either when terminating the LC molecules or separating monomers in dimers or polymers, or by the parity of the number of rigid mesogenic units separated by odd numbered methylene spacers. These odd-even effects are manifested themselves in the transition temperatures (mainly of the clearing point) and transition entropies, but they can also lead to alteration of phases, such as antiferroelectric or ferroelectric, or the appearance of tilted or orthogonal mesophases. These alternating phase and entropy properties then also lead to alternating secondary properties, such as in birefringence and elastic properties. In each category, we also discuss the theoretical considerations that can explain the observed odd-even effects.
ISSN:0267-8292
1366-5855
DOI:10.1080/02678292.2021.2000054