The thermotropic phase behavior of ascorbyl palmitate: an infrared spectroscopic study

Abstract

The infrared spectra of aqueous potassium ascorbyl palmitate were studied as a function of temperature using Fourier transform infrared techniques. From a light scattering experiment the Krafft point of 0.1 M potassium ascorbyl palmitate was determined to be 48 °C. The temperature-induced changes in infrared spectral parameters such as frequency and bandwidth characterize this Krafft point as a phase transition from a conformationally ordered, poorly hydrated solid phase, to an isotropic micellar phase. The phase transition of this "pseudosoap" occurs over a temperature range of about 10 °C, reflecting the progressive hydration of the solid upon micellization, a behavior typical of surfactants such as soaps.