The formation of oligomers in the inhibited thermal copolymerisation of styrene and acrylonitrile

Abstract

AbstractThe formation of oligomers up to molecular weights as high as about 800 was investigated in the iodine‐ and 4‐nitrosophenol‐inhibited thermally initiated copolymerisation of styrene and acrylonitrile by using column exclusion chromatography. In contrast to other possible approaches, such as the estimation of the rate of inhibition by analysing the inhibition period or trapping the initiating radicals through spin traps, this method offers the advantage of detecting the molecular species appearing during the inhibition reaction by directly estimating their molecular weights even in the higher ranges. A structural assignment of the discovered species is suggested and supported by the results of copolymerisation statistics. With iodine and 4‐nitrosophenol as inhibitors, the oligomers of the thermal reaction of copolymerisation initiation, the reaction products of inhibitors with initiating radicals, as well as components of a higher molecular weight were detected and classified, and the mechanisms of their formation are discussed.