Conformations of tethered polymer chains: a fluorescence energy transfer study

Investigations have been carried out to probe the conformations of tethered poly(ethyleneglycol) (PEG) chains anchored on polystyrene (PS) latex parti cles in presence of an anionic surfactant, sodium dodecyl sulfate (SDS) and two inorganic salts, sodium and potassium chloride. For this purpose, PS l atex particles were labeled with pyrene and mononaphthayl PEG ester. Distan ce dependent nonradiative energy transfer from naphthalene moieties to pyre ne moieties was used as a ruler in this study. Results showed that the sepa ration distance between the acceptor and the donor changes with external st imuli. Analysis of the results suggested that there is considerable contrac tion of the polymer chain upon interaction with salts and surfactant below its critical micelle concentration. The study also reveals that SDS interac ts with PEG chains bellow its critical micellar concentration, probably due to binding of SDS counterions to PEG chains. (C) 2001 Elsevier Science Ltd . All rights reserved.