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

Abstract

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 10 6 Hz, which was considered as the interface polarization ascribed to the interface between water and liquid phases (W and L 1). With the temperature increasing further, a new dielectric relaxation was observed at about 10 4 Hz, which was assigned to the appearance of liquid crystal phase (L α). According to the dielectric parameters fitted by Cole–Cole equation, the coexistence temperature of W, L 1 and L α was determined at about 37.0 °C.