Self-assembling Structures and Sol-Gel Transition of Optically Active and Racemic 12-Hydroxystearic Acids in Organic Solvents

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• 作者：Hiroyuki Takeno ; Tomomitsu Mochizuki ; Kazuto Yoshiba ; Shingo Kondo ; Toshiaki Dobashi
• 关键词：Self ; assembling structures ; Sol ; gel transition ; Low ; molecular weight gelator ; Small ; angle X ; ray scattering
• 刊名：Progress in Colloid and Polymer Science
• 出版年：2009
• 出版时间：2009
• 年：2009
• 卷：136
• 期：1
• 页码：47-53
• 全文大小：164.0 KB

文摘

Self-assembling structures and sol-gel transition in solution of optically active and racemic 12-Hydroxystearic acids (HSA) have been investigated by means of small-angle X-ray scattering (SAXS), differential scanning calorimetry and rheological measurements. Apparently two kinds of gel, transparent gel and turbid gel were obtained in different solvents or by changing concentrations in the same solvent. The melting temperature of the turbid gel is higher than that of the transparent gel. The difference can be qualitatively explained by the dissolution of the crystals (melting point depression) in non-ideal solutions. The SAXS profiles of the transparent gel composed of fibrillar structures have a similar shape at different concentrations, although the intensity is larger for the gels with higher concentrations of 12-HSA. The SAXS analysis reveals that the cross-section of fibrils have square or circular shape (no anisotropic shape) with the radius of gyration 83 ?. On the other hand, for the turbid gel structural inhomnogeneity becomes significant with concentration. The gelation properties and the structures are found to be similar in the racemic HSA gel and the optically active (D-HSA) gel.