Abstract
In a titration calorimetric study an aqueous solution held in a syringe and containing hexadecyltrimethylammonium bromide (CTAB; 15.4×10−3 mol dm−3) is injected in aliquots (5×l0−3 dm3) into a sample cell containing initially water. Analysis of the data shows that thecmc equals 0.97×l0−3 dm−3 and the enthalpy of micelle formation equals −10.3 kJ mol−1. When the solution in the syringe is replaced by a mixed surfactant solution, CTAB+dodecyltrimethylammonium bromide, at the same total concentration of surfactant, thecmc of CTAB decreases gradually with increasing mole fraction of DOTAB but the enthalpy of CTAB micelle formation is hardly affected. We conclude, therefore, that incorporation of DOTAB monomers into the CTAB micelles stabilizes entropically the CTAB micelles.
Similar content being viewed by others
References
J. K. Grime, Analytical Solution Calorimetry, Wiley, New York, 1985, Chapter 6.
K. Bijma, J. B. F. N. Engberts, G. Haandrikman, N. M. van Os, M. J. Blandamer, M. D. Butt and P. M. Cullis, Langmuir, 10 (1994) 2578.
J. Bach, M. J. Blandamer, J. Burgess, P. M. Cullis, L. G. Soldi, K. Bijma, S. Noordman, J. B. F. N. Engberts, A. Kacperska, K. C. Rao and M. C. S. Subha, J. Chem. Soc., Faraday Trans., 91 (1995) 1229.
N. M. van Os, J. R. Haak and L. A. M. Rupert, Physico-Chemical Properties of Selected Anionic, Cationic and Non-Ionic Surfactants, Elsevier, Amsterdam 1993.
J. Bach, M. J. Blandamer, J. Burgess, P. M. Cullis, P. Tran, L. G. Soldi, K. C. Rao, M. C. S. Subha and A. Kacperska, J. Phys. Org. Chem., 8 (1995) 108.
N. M. van Os, G. J. Daane and G. Haandrikman, J. Coll. Int. Sci., 141 (1991) 1999.
Author information
Authors and Affiliations
Additional information
We thank EPSRC for their support; the Commonwealth Scholarship Commission for an award to MCSS and the Royal Society for a grant awarded to PMC for the purchase of the Titration Microcalorimeter.
Rights and permissions
About this article
Cite this article
Blandamer, M.J., Cullis, P.M., Soldi, L.G. et al. Effects of added dotab on thecmc and enthalpy of micelle formation at 298.2 K for CTAB(aq). Journal of Thermal Analysis 46, 1583–1588 (1996). https://doi.org/10.1007/BF01980764
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01980764