Water-Soluble Copolymers .61. Microstructural Investigation of Pyrenesulfonamide-Labeled Polyelectrolytes: Variation of Label Proximity Utilizing Micellar Polymerization

Synthesis of a series of pyrenesulfonamide-labeled polyelectrolytes viith varied label proximities has been accomplished by a micellar polymerization technique. The solution properties of these terpolymers consisting of acrylamide (AM), acrylic acid (AA), and N-[(1-pyrenylsulfonamido)ethyl]-acrylamide (APS) are examined using viscometry, light scattering, and fluorescence spectroscopy. Classical light scattering indicates high molecular weights (\u3e1 x 10(6)) and very good polymer solvation even at high NaCl concentrations (A(2) similar to 10(4) cm(3) mol/g(2)). Viscometry and dynamic light scattering studies indicate no interpolymer aggregation of the hydrophobic APS labels. Also, no intermolecular associations are evident through measurement of I-E/I-M as a function of terpolymer concentration in 0.5 M NaCl or at pH 3 and 7. Further photophysical results are interpreted on the basis of intramolecular excimer formation. Steady-state fluorescence emission studies indicate that I-E/I-M scales with the surfactant to APS ratio (SMR) in polymerizations. Also, I-E/I-m is a linear function of n, the initial number of APS monomer molecules per micelle. Steady-state excitation and time-resolved fluorescence emission studies have been utilized to probe the microenvironment surrounding the APS labels at varying polymer concentration, electrolyte concentration, and pH values