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

• Published in: Liquid crystals Vol. 43; no. 1; pp. 102 - 111
• Main Authors: Salud, J., López, D.O., Sebastián, N., de la Fuente, M.R., Diez-Berart, S., Ros, M.B.
• Format: Journal Article Publication
• Language: English
• Published: Abingdon Taylor & Francis 02-01-2016; Taylor & Francis Ltd
• Subjects: Anàlisi espectral; Calorimetry; Chains; Crystallography; Dielectric spectroscopy; Dielectrics; Dimers; Enginyeria química; Entropia; Entropy; Latent heat; LCDs; Liquid crystal dimers; Liquid crystal displays; Liquid crystals; MDSC; N-to-I phase transition; Phase transformations; Phase transitions; Química física; Spectrum analysis; Tricritical behaviour; Àrees temàtiques de la UPC
• ISSN: 0267-8292; 1366-5855
• DOI: 10.1080/02678292.2015.1066890

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.