PHOTOOXIDATIVE DEGRADATION OF POLY(2,6-DIMETHYL-1,4-PHENYLENE OXIDE) IN THE PRESENCE OF CONCENTRATED HYDROXY PEROXIDE - THE ROLE OF HYDROXY(HO-CENTER-DOT) AND HYDROPEROXY (HO2-CENTER-DOT) RADICALS

The reaction of poly(2,6-dimethyl-1,4-phenylene oxide) with hydroxy (H O') and hydroperoxy (HO2) radicals generated by the UV photolysis of c oncentrated hydrogen peroxide (H2O2) (3Swt%) has been studied. The HO. /HO2(.) radicals accelerate the photo-oxidative chain-scission of a po lymer, in comparison with photo-oxidative degradation in air or in wat er. However, both HO. and HO2. radicals undergo additional reactions t o the aromatic phenyl rings in a polymer. Spectroscopic analyses sugge st the presence of phenols and hydroxy-mucondialdehydes among the phot o-oxidation products, indicating that HO. and HO2. addition occurs at the phenyl groups of the polymer. Rearrangement of hydroxy-phenyl radi cals can also produce quinoide structures. Coloration of the polymer c an result from formation both of quinone and hydroxy-mucondialdehyde s tructures in photo-oxidized polymer. The significance of HO. radicals formed from the thermolysis and/or photolysis of hydroperoxides in the polymer is considered.