FLUORESCENCE QUENCHING STUDIES OF THE INTERACTION OF A PYRENE-LABELEDPOLYELECTROLYTE WITH QUENCHER-CARRYING OPPOSITELY CHARGED MICELLES

The interaction between poly(sodium 2-(acrylamido)-2-methylpropanesulf onate) labeled with 1 mol % pyrene (PyPAMPS) and mixed micelles of hex aethylene glycol n-dodecyl monoether (C12E6) and n-hexadecyltrimethyla mmonium chloride (CTAC), in which N,N-dimethylaniline (DMA) was solubi lized, was studied by steady-state and time-dependent fluorescence que nching by varying the mole fraction of CTAC (Y) in the mixed micelle. At Y < 0.05, fluorescence quenching is essentially dynamic, arising fr om collisional encounters of the pyrene Sites and DMA-carrying mixed m icelles. Strong quenching begins to occur at Y congruent to 0.05, corr esponding to the onset of polyelectrolyte-micelle interactions. In the region 0.05 < Y < 0.09, the quenching was shown to occur via transien t complex formation between PyPAMPS and the mixed micelle. Changes in the vibrational structures of fluorescence spectra of pyrene in PyPAMP S indicate that pyrene groups are inserted in the hexa(oxyethylene) ph ase of the mixed micelle when the polymer-micelle complex is formed. T he extent of quenching reaches a limiting value at Y > 0.11 in excess micelle solution, corresponding to the state in which all pyrene group s are micelle-bound.