Low-Temperature Dielectric Relaxation in the System Silica Gel – Undecylenic Acid

The paper discusses the influence of silica gel pores' size on the structure and the dielectric properties of the nanocrystals of undecylenic acid with the view of determining molecular mechanisms of the possible pharmacological activity of similar substances. To achieve these goals, the powder XRD method was utilized. The nanocrystals formed in the silica gel pores show the absence of order along the long axes of molecules. The dielectric relaxation in the bulk undecylenic acid and its nanocrystals was studied using dielectric spectroscopy. The decrease in pores' size led to a decrease in the temperatures of the relaxation process. We relate this shift to the formation of additional stresses in the nanocrystals caused by the interaction with the silica gel walls.