Wang Yi, Fantin Marco, Park Sangwoo, Gottlieb Eric, Fu Liye, Matyjaszewski Krzysztof
Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213.
Macromolecules. 2017 Oct 24;50(20):7872-7879. doi: 10.1021/acs.macromol.7b02005. Epub 2017 Oct 13.
An electrochemically mediated reversible addition-fragmentation chain-transfer polymerization (RAFT) of (meth)acrylates was successfully carried out via electroreduction of either benzoyl peroxide (BPO) or 4-bromobenzenediazonium tetrafluoroborate (BrPhN) which formed aryl radicals, acting as initiators for RAFT polymerization. Direct electroreduction of chain transfer agents was unsuccessful since it resulted in the formation of carbanions by a two-electron transfer process. Reduction of BrPhN under a fixed potential showed acceptable control, but limited conversion due to the generation of a passivating organic layer grafted on the working electrode surface. However, using fixed current conditions, easier to implement than fixed potential conditions, conversions > 80% were achieved. Well-defined homopolymers and block copolymers with a broad range of targeted degrees of polymerization were prepared.
通过对过氧化苯甲酰（BPO）或四氟硼酸4-溴苯重氮盐（BrPhN）进行电还原成功实现了（甲基）丙烯酸酯的电化学介导可逆加成-断裂链转移聚合（RAFT），这两种物质均可形成芳基自由基，作为RAFT聚合的引发剂。链转移剂的直接电还原未成功，因为这会通过双电子转移过程形成碳负离子。在固定电位下对BrPhN的还原显示出可接受的可控性，但由于在工作电极表面接枝形成了钝化有机层，导致转化率有限。然而，使用比固定电位条件更易于实施的固定电流条件，实现了>80%的转化率。制备了具有广泛目标聚合度的结构明确的均聚物和嵌段共聚物。
