Opposite effects of a singlet oxygen quencher on photochemical degradation of dicyano-substituted poly(phenylenevinylenes) with different side chains

RO-diCN-PPV and C8-diCN-PPV photodegrade via singlet oxygen mechanism and RO-diCN-PPV is seven times more stable. 1,4-diazabicyclo[2.2.2]octane (DABCO), a well-known singlet oxygen quencher, exhibits opposite effects on photodegradation of the polymers. With 15 mol% DABCO, degradation rate of C8-diCN-PPV decreased by 65%, while that of RO-diCN-PPV increased by 246%. Electron donation from DABCO to RO-diCN-PPV can happen upon photoexcitation and results in generation of DABCO cationic radicals which initiate a radical process that damages the polymer and destroys DABCO.