The Middle Soap-Isotropic Transition at High Pressures in OPE₁₀/Water

Abstract

The middle soap-isotropic phase transition in p, t-octylphenoxynonaethoxyethanol (OPE₁₀) and water systems is examined at high pressures. It is found that the melting curves in the P-T plane share some characteristics with transitions in thermotropics but are generally much steeper than in other liquid crystalline systems. The strong curvature of the melting line for one concentration allows transitions from isotropic to condensed to isotropic phases when changing pressure at a fixed temperature. The effect of increasing pressure on the peak in transition temperature as a function of concentration is to move it toward higher concentrations.