Polymer radicals derived from diethyl, diisopropyl, dicyclohexyl and di-tert-butyl fumarates were spin-trapped with 2,4,6-tri-tert-butylnitrosobenzene (BNB), which yields an anilino radical and a nitroxide depending on the steric environment of the radical centre. The spin adduct was prepared by fumarate polymerization initiated with di-tert-butyl hyponitrite in the presence of BNB and by the reaction with active poly (fumarate) radical. According to the e.s.r, spectra of the spin adducts, increases in the bulkiness of the ester alkyl group and the polymer chain length brought about a larger quantity of the anilino radical. This finding indicates the tendency that the reactivity of poly (fumarate) radical toward BNB is differentiated by the steric hindrance caused by the polymer chain and the ester alkyl group
Посилання на статтю:
Observation of steric effect in radical polymerization of dialkyl fumarates by spin trapping with 2,4,6-tri-tert-butylnitrosobenzene / Bunichiro Yamada, Eiichiro Yoshikawa and Takayuki Otsu // Polymer. – 1992. – Vol 33. – P. 3245-3251.