Electron Spin Resonance Study of Monomeric, Dimeric, and Polymeric Acrylate Radicals Prepared Using the Atom Transfer Radical Polymerization TechniqueDirect Detection of Penultimate-Unit Effects
作者:Atsushi Kajiwara、Ajaya Kumar Nanda、Krzysztof Matyjaszewski
DOI:10.1021/ma035516s
日期:2004.2.1
dimers provided radicals mimicking the active species in a radical copolymerization of MA, MMA, and tBA. Well-resolved ESR spectra of the dimeric radicals confirm electronic and steric effects of the penultimate unit on the propagating radical. Hyperfine splitting constants observed for monomeric, dimeric, oligomeric, and polymeric tert-butyl acrylate radicals depend on the polymer chain length. The
通过电子自旋共振(ESR)研究了有机锡化合物与通过原子转移自由基加成(ATRA)或原子转移自由基聚合(ATRP)制备的自由基前体反应生成的模型自由基。各种(甲基)的二聚物丙烯酸酯单元,丙烯酸甲酯(MA),叔-丁基丙烯酸酯(吨BA)和甲基丙烯酸甲酯(MMA),MA-MA-BR,MA-吨BA-BR,吨BA-吨BA- BR,MMA-吨BA-Br和MA-MMA-BR,由ATRA制备。这些二聚体在MA,MMA和t的自由基共聚中提供了模仿活性物种的自由基。爸 良好解析的二聚体基团的ESR光谱证实了倒数第二个单元对正在传播的基团的电子和空间效应。对于单体,二聚,低聚和聚合的丙烯酸叔丁酯基团观察到的超细分裂常数取决于聚合物链长。将ESR谱随链长和倒数第二个单元的变化与使用CuBr / bpy催化剂系统在ATRP中活化的速率常数进行了比较。