Synergistic effects in binary surfactant mixtures
2004 (English)In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 123, 16-22 p.Article in journal (Refereed) Published
By considering the main contributions to the micellar free energy we have analysed the synergistic effect often seen on the CMC of a binary surfactant mixture. The synergistic effects are due mainly to the entropic free energy contributions related with the surfactant head groups. Several cases have been treated: (i) For a mixture of a monovalent ionic and a non-ionic surfactant in the absence of added salt we obtain, entirely because of electrostatic reasons, a negative deviation from the ideal behaviour corresponding to an interaction parameter β≈-1. Upon adding an inert salt we found that the magnitude of the synergistic effect first increases, reaches a maximum and eventually decreases. (ii) For mixtures of two ionic surfactants with the same charge number but with different hydrocarbon moieties β-values as low as -10 may arise. (iii) For mixtures of an anionic and a cationic surfactant enormous effects are anticipated yielding β≤-20 depending on the CMCs of respective pure surfactant. (iv) Synergistic effects due to different cross-section areas of the head groups are found to be rather small, with 0 > β > -1, provided the difference in head group size is modest but can become more significant when the size difference is larger.
Place, publisher, year, edition, pages
2004. Vol. 123, 16-22 p.
hydrocarbon, ionic surfactant, nonionic surfactant, surfactant, conference paper, electricity, electrochemistry, energy, entropy, micelle, molecular interaction, parameter
Other Chemical Engineering
IdentifiersURN: urn:nbn:se:kth:diva-157428ScopusID: 2-s2.0-3042788555OAI: oai:DiVA.org:kth-157428DiVA: diva2:771583
QC 201412152014-12-152014-12-092014-12-15Bibliographically approved