Fluorescence probe and pulsed field gradient NMR study of aqueous solutions of poly(ethylene oxide)-polypropylene oxide)-polyethylene oxide) block copolymer F88

In aqueous solutions of the triblock copolymer F88 (EO96PO39EO96) micelle f ormation has been studied by means of dual fluorescence of the probe molecu le 1,3-bis(1-pyrene)propane monitoring viscosity changes in its microenviro nment. Mobility changes of the polymer molecules on micellization were foll owed by means of pulsed field gradient (PFG) NMR. These results complement a recent detailed study of cis-trans isomerization of azo dyes as "kinetic probes" for structure formation in aqueous solutions of F88 (Langmuir 2001, 17, 2907). Differences of the critical micellization temperatures determin ed by various methods, and in H2O and D2O as solvents, are discussed. Our r esults reflect the particular large content of polye(ethylene oxide) in F88 (80%) compared to other triblock copolymers of this type.