Correlation between micellar structure and cloud point in long poly(oxyethylene)n oleyl ether systems

Citation
K. Shigeta et al., Correlation between micellar structure and cloud point in long poly(oxyethylene)n oleyl ether systems, LANGMUIR, 17(16), 2001, pp. 4717-4723
Citations number
43
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
LANGMUIR
ISSN journal
0743-7463 → ACNP
Volume
17
Issue
16
Year of publication
2001
Pages
4717 - 4723
Database
ISI
SICI code
0743-7463(20010807)17:16<4717:CBMSAC>2.0.ZU;2-B
Abstract
Phase behavior, micellar structure, and cloud point have been investigated in water/long poly(oxyethylene)(n) oleyl ether (C18:1EOn) (n = 10. 7, 19.2, 30.1, and 50.8) systems. With increasing n, the discontinuous micellar cub ic phase (I-1) becomes increasingly stable, effectively replacing hexagonal and lamellar liquid crystalline phases. From NMR self-diffusion measuremen ts in the liquid micellar phase at lower concentrations, we found that mice lles at larger n remain spherical and interact to a good approximation as h ard spheres up to crystallization. In the cubic phase, small-angle X-ray da ta indicate a body-centered cubic arrangement. The aggregation number of th e micelles monotonically decreases with increasing EO chain length, but the micellar molecular weight first decreases and then turns to increase at a certain EO chain length because of the increase of molecular weight of the surfactant molecule. As a result, the cloud point first increases with incr easing EO chain length, reaches a maximum, and then slightly decreases as t he EO chain length is further increased. Comparison was also made of the cl oud-point behavior of poly(oxyethylene)(n) polymer systems with that of the C18:1EOn systems.