Bend and splay elastic constants and the rotational viscosity of nematic decylammonium chloride and ammonium chloride water mixtures

Elastic and dynamic properties of two amphiphilic nematic mixtures consisting of decylammonium chloride and NH₄Cl, molar ratio 2.76:1, and water, 90.5 and 89.7 mole %, respectively, were studied on thin surface aligned films. The data can be successfully analyzed on the basis of the Frank–Oseen and Leslie–Erickson theory. The magnitude of the curvature elastic constants is comparable to that of typical thermotropic nematics. The mixtures have a nematic range of 20 °C and transform in cooling to neat soap. The bend elastic constant and the rotational viscosity diverge at this transition while the splay elastic constant shows no critical behavior.