Radical transfer on styrenic macromonomers of polyoxyethylene—II. Studies on model compounds

✍ Scribed by T. Hamaide; A. Revillon; A. Guyot

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 557 KB
• Volume: 23
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(87)90123-6

✦ Synopsis

In a previous study of the copolymerization of butyl acrylate with styrenic macromonomers, it was shown that benzylic hydrogen atoms are involved in a transfer process. In order to investigate these latter reaction, model compounds were synthesized and used as transfer agents in the polymerization of butyl acrylate. For a non-substituted benzylic ether, i.e. having two benzylic hydrogen atoms, the transfer constant was estimated to be around 0.0021; kinetic studies showed that the efficiency of reinitiation is about 80%. Replacement of a benzylic hydrogen atom by a methyl group led to a transfer process with no reinitiation. The measured transfer constant was 0.0018. The concentrations of the propagating and transferring radicals were calculated using the Jenkins and Kice equations. For the non-substituted ether, these methods did not fit our kinetic data. The incorporation of the transfer agents in the polymer was followed by GPC, u.v. and NMR spectroscopies. It appears that some polymer chains may include more than one transfer agent unit, though a statistic counting has shown the average number of transfer agent units per polymer chain to be less than one, even with a high reinitiation efficiency.