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Advisor(s)
Abstract(s)
In a recent article [ M. H. Godinho et al., Liq. Cryst. 35, 103 ( 2008)] we reported that sheared films of two n-alkylimidazolium salts exhibit liquid crystalline behaviour below their bulk equilibrium freezing temperature. The resulting morphologies are strongly reminiscent of two-dimensional liquid foams: the materials partition into dark domains ( cells) separated by brighter ( birefringent) walls, which are approximately arcs of circle and meet at vertices ("Plateau borders") with three or more sides. Here we investigate whether they satisfy known quantitative results for foams [see, e. g. D. Weaire and S. Hutzler, The Physics of Foams ( Oxford University Press, Oxford, 1999)]. We find that: (i) where three walls meet, they do so at approximately 120 degrees angles, for all times studied; (ii) Lewis's law of linear relation between cell area and number of sides is approximately satisfied at late times; (iii) the morphological patterns coarsen in time, both T1 and T2 processes are observed and, at late times, evolution is consistent with von Neumann's law; and (iv) relatively large numbers of 5-sided cells survive up to fairly late times. Results ( i) and ( iii) suggest that surface tension may play a key role in determining the physics of this system, as it does in low-viscosity liquid foams.
Description
Philosophical Magazine Letters
Volume 88, Issue 9-10, 2008
Special Issue: Solid and Liquid Foams. In commemoration of Manuel Amaral Fortes
Keywords
Liquid foams Ionic liquid crystals Shear
Citation
CRUZ, C.; GODINHO, M. H.; FERREIRA, A. J.; KULKARNI, P. S.; AFONSO, C. A. M.; TEIXEIRA, P. I. C. - How foam-like is the shear-induced lamellar phase of an ionic liquid crystal?. Philosophical Magazine Letters. ISSN 0950-0839. Vol. 88, nr. 9-10 (2008), p. 741-747.