PHOTOOXIDATION POLY(BUTADIENE) - QUENCHING OF EXCITED-STATES BY NITROXIDES

The phosphorescence from three model bicyclic enones and those formed in thermally oxidized poly(butadiene) has been shown to be quenched efficiently by a nitroxide [3,3,4,4-tetramethyldiazetine N,N′-dioxide] in CH2Cl2:tetrahydrofuran glass at 77K. The Perrin model for static quenching was applied, and the interchromophoric distance for half-quenching found to be ∼ 12 A. At room temperature the nitroxide additive inhibited the formation of volatile products from thermally oxidized poly(butadiene) films: results also obeyed the Perrin relationship, pointing to a quenching mechanism of photostabilization. By contrast, a commercial hindered amine stabilizer was found not to act as a quencher of phosphorescence at 77K, and to have a concentration dependence for the reduction in volatile product formation at 298K in PBD films different from the nitroxide, indicating different mechanisms of action. © 1979.