PHOTOPHYSICAL PROBE STUDIES OF POLYMER-DETERGENT INTERACTIONS

The interaction of surfactants with macromolecules is of both fundamental interest and technological importance. One of the most extensively studied detergent-polymer systems is sodium dodecyl sulphate (SDS)-poly(ethylene glycol) (PEG). In aqueous solution, the PEG-SDS interaction results in the formation of micelle-like aggregates or clusters of SDS attached to the PEG polymer chain. Compared to normal SDS micelles, these SDS-PEG clusters are smaller, are more highly dissociated, and have a somewhat more ''open'' structure. In the present work, photophysical probe techniques have been employed to determine aggregation numbers of SDS-PEG clusters over a wide range of [SDS], [PEG] and added common counterion salt (NaCl), to study bimolecular encounters within the aggregates and to determine solubilities of simple organic molecules in the SDS-PEG clusters. The results emphasize the distinct nature of the SDS-PEG aggregates as compared to normal SDS micelles formed in the absence of PEG.