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additions to the phase diagram locate regions of foaminess, of preferential wetting, of capillary activity, of innate inhibition of foam, of emulsion stability, and also show which conjugate phase appears as the matrix of the liquid/liquid dispersion. Acknowledgment. The data represented by line PI in Figure 3 were obtained by Mr. R. E. Kornbrekke. The data shown in Figure 5 were obtained by Miss Carrie Woodcock.
References and Notes (1) I. Langmuir in "Coiioid Symposium Monograph", Vol. 3, H. N. Holmes, Ed., Chemical Catalog Co., New York, N.Y., 1925, p 62. (2) S. Ross and G. Nishioka, J . Phys. Chem., 79, 1561 (1975). (3) S. Ross and G. Nishioka in "Foams", R. J. Akers, Ed., Academic Press, New York, N.Y., 1976, pp 17-31. (4) J. W. Cahn, J . Chem. Phys., 66, 3667 (1977). (5) S. Ross, J . Colloid Interface Sci., 42, 52 (1973).
Ulmius et ai.
(6)S. Ross, J. Phys. Colloid Chem., 54, 429 (1950); W. E. Ewers and K. L. Sutherland, Aust. J. Sci. Res., Ser. A , 5, 697 (1952). (7) J. V. Robinson and W. W. Woods, J. SOC.Chem. Ind. (London), 67, 361 (1948). (8) S. Ross, Chem. Eng. Prog., 63 (9), 41 (1967). (9) S.Ross and G. Nishioka, J. Colloid Interface Sci., 65, 216 (1978). (10) W. D. Harkins, J . Chem. Phys., 9, 552 (1941). (11) S.Rossand R. E. Patterson, J . Chem. Eng. Data, 24, 111 (1979). (12) R. E. Patterson, Ph.D. Dissertation, Rensseiaer Polytechnic Institute, Troy, N.Y., 1978. (13) R. E. Patterson and S.Ross, Surface Sci., 81, 451 (1979). (14) J. J. Bikerman, Trans. Faraday Soc., 34, 634 (1938). (15) Landolt-Bornstein, "Zahlenwerte und Functionen", Vol. 2, Part 2, Section C, Springer-Veriag, Berlin, 1964, p 610. (16) W. D. Bancroft arid S.C. Hubard, J. Am. Chem. Soc., 64, 347 (1942). (17) T. Sasaki, Bull. Chem. Soc. Jpn., 14, 63 (1939). (18) T. Sasaki and S. Okazaki, Kolloid-Z., 159, 11 (1958). (19) G. D. Smith, C. E. Doneien, and R. E. Barden, J. Colloid Interface Sci., 60, 488 (1977). (20) N. K. Adam, "The Physics and Chemistry of Surfaces", 3rd ed,Oxford University Press, London, 1941, pp 117-1 18 (see also Dover reprint, New York, 1968).
Viscoelasticity in Surfactant Solutions. Characteristics of the Micellar Aggregates and the Formation of Periodic Colloidal Structures Jan Ulmlus, HAkan Wennerstrom,* Lennart B.-A. Johansson, Goran Lindblom, Division of Physical Chemistry 2, Chemical Center, 5-220 07 Lund, Sweden
and Signe Gravsholt Fysisk-Kemisk Instituf, The Technical University of Denmark, DTH 206, DK 2800 Lyngby, Denmark (Received November 6, 1978) Publicatlon costs assisted by the University of Lund
The properties of viscoelastic dilute aqueous solutions containing the hexadecyltrimethylammonium cation (CTA+) are investigated by monitoring the proton magnetic resonance spectrum and the linear dichroism induced in a shear gradient. It is found that the viscoelastic behavior of the dilute solutions correlates with the formation of rod-shaped micellar aggregates. This correlation is manifested both with respect to changes in composition and in temperature. It is suggested that the behavior of the solutions is caused by the presence of a periodic colloidal structure formed due to the repulsive force between the aggregates.
Introduction Aqueous solutions of some amphiphilic molecules show a striking viscoelastic behavi0r.l The viscoelasticity can, for example, be seen by simply swirling the solution and visually observing the recoil of air bubbles trapped in the solution after the swirling is stopped. The viscoelasticity is manifested in a number of other properties as, for example, a non-Newtonian viscous behavior2 and a flow-induced optical anisotropy as illustrated in Figure 1.2b Although viscoelasticity3 has been observed for a number of aqueous solutions containing ionic amphiphiles (see ref 1 and references cited therein), the property is of a rather rare occurrence. Furthermore, the chemical difference between solutions which show viscoelasticity and those which do not is sometimes smal1.l Usually the viscoelastic behavior is observed when a third component is added to a rather dilute (
