Effect of UV light on the system styrene/maleic anhydride at −196°C

The effect of UV light (λ > 300 nm) on the system styrene/maleic anhydride/solvent (acetone or chloroform) in the presence and/or absence of the alternating styrene/maleic anhydride copolymer was studied by the ESR method at −196°C. It was found that the concentration of paramagnetic species increased with the time of irradiation. The intensity of the ESR spectra at −196°C did not change when the light was cut off. By analysis of the ESR spectra of the systems studied the methyl (aH = 2,3 mT), dichloromethyl (aH = 1,66 mT), and acetyl (aH = 0,52 mT) radicals as well as the radicals A and D (aHα = 2,25 mT, aHβ = 3,19 mT) and (aHβ = 1,1 mT), respectively, were identified.