Selenium-Centered Radical Mediated Polymerization

Kwon and coworkers have reported the use of diphenyl diselenide 28 and a variety of ben/.ylic selenides ( .. 29,30, 31 and 32 ) as photoiniferters for polymerization of S, MM A and some derivatives. Very narrow dispersities were not obtained ( M / M typically 2-2.5). However, it was possible to prepare block copolymers. A related visible light photoinitiation system has recently been reported comprising l-(phenylseleno)ethylbenzene and /-butyl(diphcnyl)(phcnylsclcno)silanc.  

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Most polymerizations in this section can be categorized as stable (Tree) radical-mediated polymerizations (sometimes abbreviated as SFRMP). In the following discussion systems have been classed according to the type of stable radical involved, which usually correlates with the type of bond homolyzed in the activation process. Those described include systems where the stable radical is a sulfur-ccntered radical (Section 9.3.2), a selenium-centered radical (Section 9.3.3), a carbon-centered radical (Sections 9.3.4 and 9.3.5), an oxygen-centered radical (Sections 9.3.6, 9.3.7), or a nitrogcn-ccntcrcd radical (Section 9.3.8). Wc also consider polymerization mediated by cobalt complexes (Section 9.3.9) and certain monomers (Section 9.3.5). 

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