H. Gutman, Z. Luz, J. Charvolin
Nov 1, 1987
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Influential Citations
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Journal
Liquid Crystals
Abstract
Abstract Mixtures of the dipotassium salt of thapsic acid (dipotassium hexadecanedioate, KOOC(CH2)14COOK) and water exhibit lyomesophases at disoap concentrations between 40 and 65 wt % and temperatures above c. 50°C. The phase diagram of this system has been studied by deuterium and potassium-39 N.M.R., and by optical microscopy. Mixtures of the disoap and water were studied as a function of concentration and temperature, in ordinary bulk samples, and in rectangular cells packed with parallel glass plates to allow measurements on oriented samples. The main features of this system are: between c. 40 and 55 wt % disoap, on cooling from the isotropic liquid, a single uniaxial phase appears with δχ > 0, while cooling solutions with disoap concentrations between 55 and 65 wt %, yield two phases separated by a first order transition; a high temperature phase (HTP) with δχ lt; 0, and a low temperature phase (LTP) with δχ < 0. The latter phase is identified with that observed at lower disoap concentrations. On h...