The polymerization of styrene by sulphuric acid IV. Chain-stopping agents and mechanisms

Abstract

Alcohols, nitromethane and triphenyl methyl compounds are shown to cause a large depres­sion of molecular weight and yield in the cationic polymerization of styrene by sulphuric acid at 25°C. Ether, acetone and iso propyl benzene have a weaker effect. Where the equivalent of the Mayo transfer equation is obeyed, the ‘molecular transfer constants’ have been determined. Nitromethane and the triphenyl methyl compounds are anomalous in this respect. There is evidence that all the polar substances interact to a greater or less extent with the catalyst, as well as with the growing chains.