Identification of transitions in lyotropic mesophases in hexaethylene glycol dodecyl ether–water by precision densimetry

Abstract

The temperature dependence of the density has been measured for several concentrations of the hexaethylene glycol dodecyl ether (C12E6)–water (H2O) system, which exhibited lyotropic mesophases. The transitions from the lamellar (Lα) phase to the micellar solution (L1) phase and from the hexagonal (H1) phase to the micellar solution phase are of first order, and the molecular packing in the Lα phase is closer than that in the H1 phase. The mixture with 65.0 wt.% C12E6 exhibits L1, cubic (V1), H1 and Lα phases. The individual phase transitions between the H1, V1, Lα and L1, phases in sequence were clearly evident in the reduced density. The H1–V1 and V1–Lα phase transitions are of second order.