Interaction of the Nonionic Surfactant C12E8 with High Molar Mass Poly(ethylene oxide) Studied by Dynamic Light Scattering and Fluorescence Quenching Methods

Abstract

Dynamic light scattering has been used to investigate ternary aqueous solutions of n-dodecyl octaoxyethylene glycol monoether (C12E8) with high molar mass poly(ethylene oxide) (PEO). The measurements were made at 20 °C, always below the cloud point temperature (Tc) of the mixed solutions. The relaxation time distributions are bimodal at higher PEO and surfactant concentrations, owing to the presence of free surfactant micelles, which coexist with the slower component, representing the polymer coil/micellar cluster complex. As the surfactant concentration is increased, the apparent hydrodynamic radius (RH) of the coil becomes progressively larger. It is suggested that the complex structure consists of clusters of micelles sited within the polymer coil, as previously concluded for the PEO−C12E5−water system. However, C12E8 interacts less strongly than C12E5 with PEO; at low concentrations of surfactant the complex does not contribute significantly to the total scattered intensity. The perturbation of the PE...