Interaction between poly(ethylene glycol) and two surfactants investigated by diffusion coefficient measurements.

Dynamic light scattering (DLS) and fluorescence recovery after pattern photobleaching (FRAPP) were used to study the interaction of low molecular weight poly(ethylene glycol) (PEG) with micelles of two different surfactants: tetradecyldimethyl aminoxide (C14DMAO, zwitterionic) and pentaethylene glycol n-dodecyl monoether (C12E5, non-ionic). By using an amphiphilic fluorescent probe or a fluorescent-labeled PEG molecule, FRAPP experiments allowed to follow the diffusion of the surfactant–polymer complex either by looking at the micelle diffusion or at the polymer diffusion. Experiments performed with both fluorescent probes gave the same diffusion coefficient showing that the micelles and the polymer form a complex in dilute solutions. Similar experiments showed that PEG interacts as well with pentaethylene glycol n-dodecyl monoether (C12E5).