Reactions of polystyrene radicals in a monomer-free atom transfer radical polymerization system
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- Chiaki Yoshikawa
- 1Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan; Fax +81-774-38-3170
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- Atsushi Goto
- 1Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan; Fax +81-774-38-3170
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- Takeshi Fukuda
- 1Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan; Fax +81-774-38-3170
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説明
<jats:title>Abstract</jats:title><jats:p>Polystyrene radicals (PS<jats:sup>•</jats:sup>) were produced in high concentration using <jats:italic>ω</jats:italic>-bromopolystyrene (PS-Br) and <jats:italic>α</jats:italic>,<jats:italic>ω</jats:italic>-dibromopolystyrene (Br-PS-Br) in conjunction with Cu(I)Br following the atom transfer technique. A proper choice of the activator system led the PS-Br adduct to a maximum extent of coupling (by recombination), <jats:italic>q</jats:italic><jats:sub>max</jats:sub> = 0.91, as estimated by gel permeation chromatography. On the other hand, the fraction of chains terminated by disproportionation was estimated to be 0.07 ± 0.04 by <jats:sup>1</jats:sup>H NMR. When the radical concentration [PS<jats:sup>•</jats:sup>] was not high enough, the chain transfer reaction competed with termination, and <jats:italic>q</jats:italic><jats:sub>max</jats:sub> remained low. For the bifunctional adduct Br-PS-Br, the coupling reaction produced ‘polymers’ of a variety of chain lengths, whose distribution obeyed the theory of random coupling, when <jats:italic>q </jats:italic>was lower than about 0.5. The high extent of coupling (<jats:italic>q</jats:italic><jats:sub>max</jats:sub> ≈ 0.9) achievable in short time (< 10 min) suggests practical applicability of this reaction.</jats:p>
収録刊行物
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- e-Polymers
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e-Polymers 2 (1), 2002-12-01
Walter de Gruyter GmbH