FLUORESCENCE STUDIES OF THE INTERACTION OF SODIUM DODECYL-SULFATE WITH HYDROPHOBICALLY MODIFIED POLY(ETHYLENE OXIDE)

A poly (ethylene oxide) (PEO, = 8000), 1, containing pyrene (Py) groups at both ends attached via ether linkages has been prepared (1), and the fluorescence properties of its aqueous solutions have been examined. These solutions show a weak excimer emission which is at first strongly enhanced and then suppressed by adding increasing amounts of sodium dodecyl sulfate (SDS) to the solutions. From the sharp onset of enhanced excimer emission and a correspondingly sharp change in the vibrational structure of the locally excited Py emission, we infer the formation of mixed micelles with an apparent cmc of 8 X 101 234 M. SDS-polymer interaction occurs at concentrations well below that of SDS with either Py itself or PEO itself, indicating that in the hydrophobically modified polymer 1 the chain and end groups act cooperatively to promote interaction with the surfactant. At low SDS concentrations, the chains tend to cyclize to put both Py groups in the same micelle. © 1990, American Chemical Society. All rights reserved.