Accessibility navigation


A SAXS study of flow alignment of thermotropic liquid crystal mixtures

Castelletto, V., Squires, A.M., Hamley, I.W., Stasiak, J. and Moggridge, G.D. (2009) A SAXS study of flow alignment of thermotropic liquid crystal mixtures. Liquid Crystals, 36 (4). pp. 435-442. ISSN 0267-8292

Full text not archived in this repository.

It is advisable to refer to the publisher's version if you intend to cite from this work. See Guidance on citing.

To link to this item DOI: 10.1080/02678290902928542

Abstract/Summary

We report on the capillary flow behaviour of thermotropic liquid crystal mixtures containing 4-n-octyl-4'-cyanobiphenyl (8CB) and 4-n-pentyl-4'-cyanobiphenyl (5CB). The liquid crystal mixtures are studied in the Nematic (N) and Smectic (SA) phases at room temperature. Polarised optical microscopy (POM), rheology and simultaneous X-ray diffraction (XRD)/capillary flow experiments are performed to characterise the system. Polarised optical microscopy reveals a dramatic change in optical texture when the 5CB content is increased from 20 to 30% in the mixtures. X-ray diffraction results show that the system goes through a SA-N phase transition, such that the mixtures are smectic for 10-20% 5CB and nematic for 30-90% 5CB. Smectic mixtures flow with the layers aligned along the flow direction (mesogens perpendicular to flow) while nematic mixtures flow with the mesogens aligned in the flow direction. Simultaneous XRD/shear flow experiments show that the SA-N transition is independent of the flow rate in the range 1-6 ml min-1. The correlation length of the liquid crystal order decreases with increasing 5CB content. Rheology is used to prove that the correlation length behaviour is related to a reduction in the viscosity of the mixture.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:11107
Uncontrolled Keywords:X-ray diffraction, nematic, smectic, mixtures, flow alignment , SMECTIC-A-PHASE, X-RAY-SCATTERING, BEHAVIOR, SHEAR, 8CB

University Staff: Request a correction | Centaur Editors: Update this record

Page navigation