Oxidation of monolayers of partly converted dimethoxy-substituted poly(p-phenylenevinylene) precursor polymers at the air-water interface

We observed that the poly(p-phenylenevinylene) units in Langmuir monolayers of partly converted dimethoxy-substituted poly(p-phenylenevinylene) precur sor polymers oxidize at the air-water interface. This reaction even happene d in the dark and therefore can not be attributed to a photooxygenation rea ction with singlet oxygen. We assume that ground-state triplet oxygen is po larized at the air-water interface and forms a weakly bound complex with th e double bond to give a reactive intermediate state, which lowers the activ ation energy of the oxidation reaction. The air-water interface thus works as a catalyst in this reaction.