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

  • Hiroyuki TakenoEmail author
  • Tomomitsu Mochizuki
  • Kazuto Yoshiba
  • Shingo Kondo
  • Toshiaki Dobashi
Part of the Progress in Colloid and Polymer Science book series (PROGCOLLOID, volume 136)

Abstract

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 Å. 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.

Keywords

Self-assembling structures Sol-gel transition Low-molecular weight gelator Small-angle X-ray scattering 

Notes

Acknowledgment

H. T. acknowledges Prof. T. Hashimoto for his valuable comments.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Hiroyuki Takeno
    • 1
    Email author
  • Tomomitsu Mochizuki
  • Kazuto Yoshiba
  • Shingo Kondo
  • Toshiaki Dobashi
  1. 1.Department of Chemistry and Chemical Biology, Faculty of EngineeringGunma UniversityKiryuJapan

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