A novel profluorescent dinitroxide for imaging polypropylene degradation

The synthesis and properties of the novel polyfluorescent dinitroxide with high quantum yield and having an ability to detect free-radical formation during polymer degradation were described. The new probe was synthesized by a Suzuki cross-coupling reaction with more reactive iodo-nitroxide as a coupling partner. The results show that the fluorescence of the degrading plaque increase over the first 300 min and then rise more rapidly between 400 and 500 min, indicating the trapping of alkyl radicals. The results also indicate that the doped plaque displays low fluorescence due to quenching by the nitroxides and also contains a significantly lower concentration of the adduct. Polypropylene doped with benzoyl peroxide and degraded at 100°C shows an area of fluorescence in the center of the plaque due to ion trapping.