Physical Gelation of Binary Mixtures of Hydrocarbons Mediated n-Lauroyl-$L$-Alanine and Characterization of Their Thermal and Mechanical Properties

Bhattacharya, Santanu and Pal, Asish (2008) Physical Gelation of Binary Mixtures of Hydrocarbons Mediated n-Lauroyl-$L$-Alanine and Characterization of Their Thermal and Mechanical Properties. In: Journal of Physical Chemistry, B, 112 (16). pp. 4918-4927.

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Abstract

Fatty acid amides, such as n-lauroyl-L-alanine, gelate both aliphatic and aromatic hydrocarbon solvents efficiently. In addition this compound is found to gelate the binary solvent mixtures comprised of aromatic hydrocarbon, e.g., toluene and aliphatic hydrocarbons, e.g., n-heptane. Scanning electron microscopy and atomic force microscopy show that the fiber thickness of the gel assembly increases progressively in the binary mixture of n-heptane and toluene with increasing percentage of toluene. The self-assembly patterns of the gels in individual solvents, n-heptane and toluene, are however different. The toluene gel consists of predominantly one type of morphological species, while n-heptane gel has more than one species leading to the polymorphic nature of the gel. The n-heptane gel is thermally more stable than the toluene gel as evident from the measurement using differential scanning calorimetry. The thermal stability of the gels prepared in the binary mixture of n-heptane and toluene is dependent on the composition of solvent mixture. Rheology of the gels shows that they are shear-thinning material and show characteristic behavior of soft viscoelastic solid. For the gels prepared from binary solvent mixture of toluene and n-heptane, with incorporation of more toluene in the binary mixture, the gel becomes a more viscoelastic solid. The time sweep rheology experiment demonstrates that the gel made in n-heptane has faster gel formation kinetics than that prepared in toluene.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry, B
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	18 May 2008
Last Modified:	19 Sep 2010 04:45
URI:	http://eprints.iisc.ac.in/id/eprint/14005

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