Micellar growth, network formation, and criticality in aqueous solutions of the nonionic surfactant C12E5

A. Bernheim-Groswasser, E. Wachtel, Y. Talmon

Research output: Contribution to journalArticlepeer-review

187 Scopus citations

Abstract

We used cryo-TEM and light scattering to study the micellar growth and subsequent network formation in aqueous solutions of the nonionic surfactant C12E5. Cryo-TEM shows the first direct evidence for the existence of connected topology in the vicinity of the critical point and the two-phase separation curve of the C12E5/water micellar system. The coexisting phases within the two-phase region consist of one concentrated and one dilute network of interconnected cylindrical micelles. These findings are consistent with the recent theoretical explanation of criticality and phase separation in certain nonionic surfactant systems as resulting from entropic attraction between network junctions. Away from the two-phase separation curve, we have identified uniaxial micellar growth, with increasing temperature and concentration, into long the threadlike micelles. From the power-law dependence of the radius of gyration, RG,z, and the hydrodynamic diameter, DH, on the molecular weight (RG,z, D̄H approx. Mwv), we find that these threadlike micelles have properties resembling those of flexible polymers in a good solvent (v approx. 0.6). Static and dynamic light scattering show that the mean micelle contour length increases as c0.5 (c is the surfactant concentration) in agreement with theory. Finally, we show that the end-cap energy Ec increases linearly with temperature.

Original languageEnglish
Pages (from-to)4131-4140
Number of pages10
JournalLangmuir
Volume16
Issue number9
DOIs
StatePublished - 2 May 2000
Externally publishedYes

Fingerprint

Dive into the research topics of 'Micellar growth, network formation, and criticality in aqueous solutions of the nonionic surfactant C<sub>12</sub>E<sub>5</sub>'. Together they form a unique fingerprint.

Cite this