Raman Spectroscopic Analysis of Surfactants in the Neat, Monomeric and Micellar Phases
Surfactant amphiphiles such as alkanoates aggregate in water to produce noncovalent assemblies called micelles. The driving force for this aggregation is the hydrophobic effect that brings the alkyl chains together into a compact assembly with minimal contact with the bulk water. Hydration of the charged or polar headgroups at the surface and inter-headgroup interactions as well as counterion binding lead to a maximization of the interfacial area of the micellar particle. The optimum compact shape that offers a large surface area and minimal volume is the sphere, and it is thus seen that most ionic surfactants of the alkyl carboxylate, sulfate or t r imet hy 1 ammon i um class tend to form spherical micelles when dispersed in pure water, beyond a concentration termed the critical micelle concentration or cmc. The standard picture of the spherical micelles of ionic surfactants has been presented recently by Gruen (1985).
KeywordsSurfactant Hydration Bromide Chloroform Polyethylene
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