Tracing Arm-Growth Initiation in Z-RAFT Star Polymerization by NMR: The Impact of the Leaving R-Group on Star Topology
Tracing Arm-Growth Initiation in Z-RAFT Star Polymerization by NMR: The Impact of the Leaving R-Group on Star Topology
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DOI：
10.1002/pola.23032
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发表时间：
2008-11-01
影响因子：
--
通讯作者：
Vana, Philipp
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文献类型：
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作者：
Boschmann, Daniel;Maenz, Martin;Vana, Philipp
在苯乙烯-d(8)的六臂Z-RAFT星形聚合中，离开基团在其初始位置的H-1核磁共振信号消失，从而引发了臂的生长。这些测量揭示了离开基团对星形聚合物拓扑结构的巨大影响。苯乙基作为离开基团，在单体转化率达到8%后就已经完全引发了星形的形成。然而，作为离开基团的苄基大大减缓了臂生长的引发，导致只有在约60%的单体转化率之后才能完全引发星形聚合物。在该值以下，不能以苯基为离开基团生成预期拓扑结构的星形聚苯乙烯。[彩色插图可在在线问题中查看，可在www.intercience.wiley.com上获得。]2008年9月25日在线发布
Arm-growth initiation in six-armed Z-RAFT star polymerization of styrene-d(8) was followed via the disappearance of H-1 NMR signals of the leaving group at their original position. These measurements revealed a dramatic impact of the leaving group on star polymer topology. Phenylethyl as leaving group induced formation of completely initiated stars already after 8% of monomer conversion. Benzyl as leaving group, however, drastically slows down arm-growth initiation, resulting in fully initiated star polymers only after about 60% of monomer conversion. Below that value, star-polystyrene of the expected topology cannot be generated with benzyl as leaving group. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.] Published online 25 September 2008