A Study of Lyotropic Mesophases of Concentrated Solutions of a Triblock Copolymer of Ethylene Oxide and 1,2-Butylene Oxide, E16B10E16, Using Rheometry, Polarized Light Microscopy, and Small-Angle X-ray Scattering

Abstract

The phase behavior and structure of aqueous solutions of a triblock copolymer of ethylene oxide and 1,2-butylene oxide, E16B10E16, have been studied as a function of polymer concentration (5−75 wt %) and temperature (5−95 °C) using tube inversion, rheometer, polarized light microscopy, and small-angle X-ray scattering. Sol−gel and gel−sol boundaries were determined by rheometry and tube inversion methods. Polarized light microscopy and small-angle X-ray scattering were used to identify the lyotropic phases. A hexagonal mesophase was found for the stiff gel region (40−52 wt %). A lamellar phase was located in the gels of concentrated solutions (≥54 wt %) by using polarized light microscopy and small-angle X-ray scattering. Furthermore, solutions with lamellar structure were detected by small-angle X-ray scattering for the mobile phases of the concentrated solutions (>44 wt %). Small-angle X-ray experiments also showed that the concentrated cloudy sols (>40 wt %) at high temperature had aggregates with lame...