Verdazyl‐Mediated Polymerization of Styrene

This is the authors' abstract. We don't add key points for this paper.

Attempted controlled polymerizations of styrene, conducted in the presence of either 1,3,5‐triphenyl‐6‐oxoverdazyl or 1,5‐dimethyl‐3‐phenyl‐6‐oxoverdazyl radicals initiated with benzoyl peroxide or 1,1′‐azobis(cyclohexanecarbonitrile) were universally unsuccessful regardless of the reaction temperature and the initiator/verdazyl molar ratio. No improvement was observed using a verdazyl‐terminated styrene initiator adduct prepared by an exchange reaction between a styrene‐TEMPO alkoxyamine and a 1,3,5‐triphenyl‐6‐oxoverdazyl radical. However, controlled polymerizations of styrene were achieved at 125 °C using a styrene‐verdazyl adduct containing the 1,5‐dimethyl‐3‐phenyl‐6‐oxoverdazyl radical. Polydispersity indexes remained low throughout the polymerizations and plots of number average molecular weight (M ₙ ) versus time were linear. However, the actual M ₙ values were considerably lower than theoretical, an unexpected result that is under investigation.