The so-called 1,3 : 2,4-di-O-benzylidene-d-sorbitol (D-DBS) can cause the gelation of alcoholic solvents. The thermal behavior of a 1 wt% d-DBS/ethylene glycol gel was studied using thermal, optical, mechanical, and spectroscopic measurements. Changes in the optical and mechanical properties were observed at around 45 and 80 °C. Upon heating, the diameter of the spherulitic texture in the gel decreased above around 45 °C and disappeared at around 80 °C. In a thermal analysis, an endothermic peak was observed at around 80 °C, which agreed with the gel state-isotropic solution phase-transition point. The aggregated structure of d-DBS in ethylene glycol was studied, using UV absorption and circular dichroism (CD) measurements. The relative orientation of the benzene rings changed above 45 °C, due to the hypochromism of the UV absorptions. The gel showed a temperature dependence of the CD spectra. With increasing temperature, the value of the molar ellipticities increased at 27—82 °C, and drastically decreased at 82—93 °C, indicating that the aggregated structure underwent a change at between 45—80 °C and disappeared above 80 °C. The macroscopic level, as well as the optical and mechanical properties were related to the change in the aggregated structure formed by d-DBS.
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Yamasaki et al. (1996) studied this question.