Controlled radical polymerization of styrene in the presence of a polymerizable nitroxide compound

Styrene is polymerized in the presence of 4-methacryloyloxy-2,2,6,6-tetrame thylpiperidine-1-oxy. The polymerization rate is higher than that using 4-h ydroxy-2,2,6,6-tetramethylpiperidine-1-oxy as counterradical. However, the molecular weight does not increase linearly with monomer conversion and the ultimate polydispersity is rather high. After posttreating with ascorbic a cid, the molecular weight decreases and a narrow polydispersity is obtained . A branched or hyperbranched structure was thus suggested.