Wang Yi, Lorandi Francesca, Fantin Marco, Chmielarz Paweł, Isse Abdirisak A, Gennaro Armando, Matyjaszewski Krzysztof
Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States.
Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy.
Macromolecules. 2017 Nov 14;50(21):8417-8425. doi: 10.1021/acs.macromol.7b01730. Epub 2017 Nov 3.
It was recently reported that copper catalysts used in atom transfer radical polymerization (ATRP) can combine with anionic surfactants used in emulsion polymerization to form ion pairs. The ion pairs predominately reside at the surface of the monomer droplets, but they can also migrate inside the droplets and induce a controlled polymerization. This concept was applied to activator regenerated by electron transfer (ARGET) ATRP, with ascorbic acid as reducing agent. ATRP of -butyl acrylate (BA) and -butyl methacrylate (BMA) was carried out in miniemulsion using Cu/tris(2-pyridylmethyl)amine (TPMA) as catalyst, with several anionic surfactants forming the reactive ion-pair complexes. The amount and structure of surfactant controlled both the polymerization rate and the final particle size. Well-controlled polymers were prepared with catalyst loadings as low as 50 ppm, leaving only 300 ppb of Cu in the precipitated polymer. Efficient chain extension of a poly(BMA)-Br macroinitiator confirmed high retention of chain-end functionality. This procedure was exploited to prepare polymers with complex architectures such as block copolymers, star polymers, and molecular brushes.
最近有报道称，原子转移自由基聚合（ATRP）中使用的铜催化剂可与乳液聚合中使用的阴离子表面活性剂结合形成离子对。这些离子对主要存在于单体液滴表面，但也能迁移到液滴内部并引发可控聚合反应。这一概念被应用于以抗坏血酸为还原剂的电子转移再生催化剂原子转移自由基聚合（ARGET ATRP）。以Cu/三（2-吡啶甲基）胺（TPMA）为催化剂，在微乳液中进行丙烯酸丁酯（BA）和甲基丙烯酸丁酯（BMA）的原子转移自由基聚合反应，使用几种阴离子表面活性剂形成反应性离子对络合物。表面活性剂的用量和结构同时控制了聚合速率和最终粒径。在催化剂负载低至50 ppm的情况下制备了可控聚合物，沉淀聚合物中仅残留300 ppb的铜。聚（BMA）-Br大分子引发剂的有效链增长证实了链端官能团的高保留率。该方法被用于制备具有复杂结构的聚合物，如嵌段共聚物、星形聚合物和分子刷。
