Phases confirmation of cloudy Silwet L-77 aqueous solution by dielectric relaxation spectroscopy

The phase transition of Silwet L-77 (a kind of siloxane surfactant) dilute aqueous solution with temperature was investigated by dielectric relaxation spectroscopy. In the initial heating process, a dielectric relaxation was found at about 106 Hz, which was considered as the interface polarization ascribed to the interface between water and liquid phases (W and L1). With the temperature increasing further, a new dielectric relaxation was observed at about 104 Hz, which was assigned to the appearance of liquid crystal phase (Lα). According to the dielectric parameters fitted by Cole–Cole equation, the coexistence temperature of W, L1 and Lα was determined at about 37.0 °C.