Influence of the chain length on the nematic-to-isotropic phase transition for the odd members of a highly non-symmetric pyrene-based series of liquid crystal dimers

ABSTRACT

This paper describes a detailed study of the nematic (N)-isotropic (I) phase transition in the homologous series of liquid crystal dimers, the α-(4-cyanobiphenyl-4ʹ-oxy)-ω-(1-pyreniminebenzylidene-4ʹ-oxy)alkanes (CBOnO.Py) by means of calorimetric and dielectric measurements as a function of temperature. It is concluded that for this transition, the latent heat or the entropy change decreases as the chain length of the odd dimers decreases, and this decrease is consistent with the observed tricritical behaviour.

Graphical Abstract

KEYWORDS:

• Tricritical behaviour
• N-to-I phase transition
• liquid crystal dimers
• MDSC
• dielectric spectroscopy

Acknowledgements

The authors thank the recognition from the Generalitat de Catalunya of GRPFM as a Consolidated Research Group (2014-SGR-190).

Additional information

Funding

The authors gratefully acknowledge the MICINN [project MAT2012-38538-C03-02,03] and the Gobierno Vasco [project GI/IT-449-10] for financial support.