GE Power and Water; Water & Process Technologies, 4636 Somerton Road, Trevose, PA 19053, USA.
Chemistry. 2012 Apr 10;18(15):4607-12. doi: 10.1002/chem.201102183. Epub 2012 Feb 29.
The field of transition-metal-mediated controlled/"living" radical polymerization (CLRP) has become the subject of intense discussion regarding the mechanism of this widely-used and versatile process. Most mechanistic analyses (atom transfer radical polymerization (ATRP) vs. single-electron transfer living radical polymerization (SET-LRP)) have been based on model experiments, which cannot correctly mimic the true reaction conditions. We present, for the first time, a determination of the [Cu(I)Br]/[L] (L=nitrogen-based chelating ligand) ratio and the extent of Cu(I)Br/L disproportionation during CLRP of methyl acrylate (MA) in dimethylsulfoxide (DMSO) with Cu(0) wire as a transition-metal catalyst source. The results suggest that Cu(0) acts as a supplemental activator and reducing agent of Cu(II)Br(2)/L to Cu(I)Br/L. More importantly, the Cu(I)Br/L species seem to be responsible for the activation of SET-LRP.
过渡金属介导的可控/“活性”自由基聚合（CLRP）领域已成为广泛应用且多功能的这一过程的机理的激烈讨论的主题。大多数机理分析（原子转移自由基聚合（ATRP）与单电子转移活性自由基聚合（SET-LRP））都是基于模型实验，这些实验无法正确模拟真实的反应条件。我们首次确定了在二甲基亚砜（DMSO）中用铜（0）丝作为过渡金属催化剂源，通过甲基丙烯酸甲酯（MA）的 CLRP，[Cu（I）Br]/[L]（L=氮基螯合配体）的比例以及 Cu（I）Br/L 歧化的程度。结果表明，Cu（0）充当 Cu（II）Br（2）/L 至 Cu（I）Br/L 的辅助活化剂和还原剂。更重要的是，Cu（I）Br/L 似乎负责 SET-LRP 的活化。
