Diminishing catalyst concentration in atom transfer radical polymerization with reducing agents
Diminishing catalyst concentration in atom transfer radical polymerization with reducing agents
复制标题
DOI：
10.1073/pnas.0602675103
复制
发表时间：
2006-10-17
影响因子：
11.1
通讯作者：
Tsarevsky, Nicolay V.
中科院分区：
文献类型：
--
作者：
Matyjaszewski, Krzysztof;Jakubowski, Wojciech;Tsarevsky, Nicolay V.
介绍了原子转移自由基聚合(ATRP)中用于连续活化剂再生(ICAR)的引发剂的概念，利用恒定的有机自由基源来再生铜-I活化剂，否则当在很低浓度下使用时，该活化剂在终止反应中被消耗。利用这一技术，可以在催化剂浓度在10-50ppm之间时实现聚苯乙烯和聚甲基丙烯酸甲酯(M-w/M-n<；1.2)的受控合成，在这种情况下，许多应用将不允许其去除或回收。此外，各种有机还原剂(联氨和苯酚的衍生物)被用来在通过电子转移(ARGET)ATRP再生的活化剂中连续再生铜-I活化剂。在催化剂浓度低至50ppm的情况下，实现了丙烯酸酯(M-w/M-n<；1.2)的受控聚合物合成。针对不同工艺中不同的副反应(即络合解离、析酸、络合)，讨论了合适的铜络合配体{三[2-(二甲氨基)乙基]胺(Me6TREN)和三[(2-吡啶)乙基]Am in e(TPMA)}的合理选择。此外，还利用机理研究和动力学建模对每个系统进行了优化。对所选催化剂/还原剂在均相聚合和嵌段聚合中的性能进行了评价。
The concept of initiators for continuous activator regeneration (ICAR) in atom transfer radical polymerization (ATRP) is introduced, whereby a constant source of organic free radicals works to regenerate the Cu-I activator, which is otherwise consumed in termination reactions when used at very low concentrations. With this technique, controlled synthesis of polystyrene and poly(methyl methacrylate) (M-w/M-n < 1.2) can be implemented with catalyst concentrations between 10 and 50 ppm, where its removal or recycling would be unwarranted for many applications. Additionally, various organic reducing agents (derivatives of hydrazine and phenol) are used to continuously regenerate the Cu-I activator in activators regenerated by electron transfer (ARGET) ATRP. Controlled polymer synthesis of acrylates (M-w/M-n < 1.2) is realized with catalyst concentrations as low as 50 ppm. The rational selection of suitable Cu complexing ligands {tris[2-(dimethylamino)ethyl]amine (Me6TREN) and tris[(2-pyridyl)m ethyl] am in e (TPMA)} is discussed in regards to specific side reactions in each technique (i.e., complex dissociation, acid evolution, and reducing agent complexation). Additionally, mechanistic studies and kinetic modeling are used to optimize each system. The performance of the selected catalysts/reducing agents in homo and block (co)polymerizations is evaluated.