Wk. Busfield et al., INVESTIGATIONS INTO THE AIBN INITIATION STEPS IN THE FREE-RADICAL POLYMERIZATION OF ACRYLONITRILE BY THE AMINOXYL TRAPPING TECHNIQUE, Polymer bulletin, 36(4), 1996, pp. 435-441
A modification of the radical trapping technique employing the stable
nitroxide 1,1,3,3-tetramethyl-2,3-dihydro- 1H-isoindol-2-yloxyl, has b
een used to study the reaction of cyanoisopropyl radicals with acrylon
itrile. By keeping the concentration of the aminoxyl radical very low
(strategically added via a syringe pump), the addition of acrylonitril
e to cyanoisopropyl radicals becomes competitive with radical trapping
. Thus, sufficient quantities of alkoxyamines produced by the trapping
of 'second generation' carbon-centred radicals (cyanoisopropyl plus o
ne monomer unit), and even 'third generation' carbon-centred radicals
were obtained for identification by HPLC / MS techniques. Trapping by
traces of adventitious oxygen was also competitive and the various per
oxy radicals thus formed, underwent addition to acrylonitrile followed
by further reaction or trapping by the aminoxyl.