Living radical polymerization of methylstyrenes by a stable nitroxyl radical, and stability of the aminoxy chain end

✍ Scribed by Eri Yoshida; Takamasa Fujii

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 163 KB
• Volume: 36
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(19980130)36:2<269::aid-pola9>3.0.co;2-m

✦ Synopsis

Radical polymerization of 2-, 3-, and 4-methylstyrenes (MeSts) was investigated with benzoyl peroxide (BPO) as an initiator, in the presence of 4-methoxy-2,2,6,6tetramethylpiperidine-1-oxyl (MTEMPO). The polymerization was performed in bulk for 3.5 h at 95ЊC, and then continued for a defined time at 125ЊC, to give the corresponding poly(MeSt)s with narrow polydispersity in high yield. It was found that the polymerization proceeded in accordance with a living mechanism, because the molecular weight of the resulting polymers was proportional to the conversion, and to the reciprocal of the initial concentration of MTEMPO. It was found that steric hindrance between the methyl group of 2-MeSt, and the tetramethyl ones of MTEMPO, significantly contributed to the rate of polymerization, and to the stability of the growing polymer chain end. The stability decreased in the order of 2ú 3ú 4-MeSt, by occurrence of decomposition, which was caused by disproportionation of the growing chain end. However, the steric hindrance had no effect on the tacticity of the resulting polymer. ᭧ 1998