Langmuir, Vol.10, No.2, 377-380, 1994
Noncritical Behavior Near the Cloud Point in Perfluorinated Ionic Micellar Solutions
The solution properties of a noncritical cloud point system, namely, sodium perfluorooctanoate/H2O/tetrapropylammonium bromide, were investigated by dynamic and static light scattering. Critical-type behavior is observed when the temperature approaches the minimum cloud point (T(d)) from the one-phase region : However, for other sodium perfluorooctanoate solutions, but of lower concentration than that corresponding to the minimum cloud-point temperature, the apparent hydrodynamic radius may decrease as the temperature approaches the cloud point. It is thus shown that a cloud-point system may not always exhibit critical-type behavior as many authors believe in the literature.
Keywords:ANGLE NEUTRON-SCATTERING;AQUEOUS-SOLUTIONS;LIGHT-SCATTERING;PHYSICOCHEMICAL PROPERTIES;SURFACTANT SOLUTIONS;ANIONIC SURFACTANTS;CRITICAL EXPONENTS;TEMPERATURE;CROSSOVER;MIXTURES