Radiation induced reactions in micellar and polymer systems

The main purpose of this work is to study the effect of aggregation on simple reactions. Aggregated systems chosen include aqueous solutions of micelles and polymethacrylic acid PMA; various radiation induced reactions such as OH radical H atom abstraction and electron transfer to quinones are studied in these systems. The interactions between ionic micelles and polymethacrylic acid, the effect of micellization on the reactivities of OH radical and the kinetics of association process in micelle systems are also investigated. The experimental techniques employed include steady state fluorescence, time-dependent fluorescence, laser-photolysis, gamma and pulse radiolysis and pulse polarography. The excited state of pyrene as observed via steady-state fluorescence and laser photolysis is used to show that pyrene is solubilized in the PMA coil in aqueous solution at pH < 4. The rates of reactions of OH-radical with monomeric surfactants are all near diffusion controlled. However when surfactants form micelles, the rates decrease at least an order of magnitude. Pulse radiolysis is employed to study these effects and combined with electron transfer reactions between monomer radicals and benzoquinones, it is possible to gain information on the kinetics of association reactions in micellar systems. PMA degrades upon irradiation, and gamma and pulse radiolysis are used to investigate the kinetics and mechanism of this degradation process. Finally pulse polarography is used to study the electrochemical properties of intermediates produced pulse radiolytically in surfactant and polymer solutions