Photochemistry of methyl viologen in aqueous solution containing polymeric carboxylic acids

Abstract

The photochemistry of methyl viologen, MV²⁺, in aqueous solution containing poly(methacrylic acid), PMAA, or poly(acrylic acid), PAA, has been investigated by laser flash photolysis and steady-state techniques. A polymer-MV²⁺ complex is formed in solution which is found to be pH dependent. The radical cation, MV^˙+, is produced immediately upon laser excitation, with a quantum yield of 0.28 under optimum conditions. PMAA was found to degrade upon irradiation, while PAA showed little change in viscosity. The data are relevant to polymer-stabilized colloidal systems used in photolytic studies.