Active, Versatile, and Removable Iron Catalysts with Phosphazenium Salts for Living Radical Polymerization of Methacrylates(1)
Active, Versatile, and Removable Iron Catalysts with Phosphazenium Salts for Living Radical Polymerization of Methacrylates(1)
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DOI：
10.1021/ma801762k
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发表时间：
2009-01
期刊：
影响因子：
5.5
通讯作者：
M. Ishio;Masao Katsube;M. Ouchi;M. Sawamoto;Y. Inoue
中科院分区：
文献类型：
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作者：
M. Ishio;Masao Katsube;M. Ouchi;M. Sawamoto;Y. Inoue
磷腈鎓卤化物（PZN-X; X = Cl，Br，I）是一种高离域性的大体积盐，与铁卤化物（FeX 2）形成原位活性阴离子Fe（II）配合物，可有效催化甲基丙烯酸烷基酯和官能化甲基丙烯酸酯的活性自由基聚合，并具有较好的催化活性和对极性官能团的耐受性。例如，FeBr 2/PZN-Br的等摩尔组合有效地诱导甲基丙烯酸甲酯（MMA）与溴化物引发剂[H-（MMA）2-Br]的活性自由基聚合，得到具有受控分子量和窄分子量分布（Mw/Mn < 1.2）的聚合物。聚合物的分子量可以在添加单体的第二进料时或在较低的引发剂剂量下增加，同时保持窄的分布。在活性和可控性方面，PZN基催化剂因此不仅与传统的铁络合物[FeBr 2（PPh 3）2; Ph = C6 H5]，而且与迄今为止已知的其他组合物显著不同。
Phosphazenium halides (PZN−X; X = Cl, Br, I), highly delocalized bulky salts, turned out to be excellent cocatalysts to be combined with iron halides (FeX2) to form in situ active anionic Fe(II) complexes that effectively catalyze living radical polymerization of alkyl and functionalized methacrylates with improved catalytic activity and tolerance to polar functionalities. For example, equimolar combinations of FeBr2/PZN−Br efficiently induced a living radical polymerization of methyl methacrylate (MMA) with a bromide initiator [H−(MMA)2−Br] to give polymers with controlled molecular weights and narrow molecular weight distributions (Mw/Mn < 1.2). Polymer molecular weight could be extended upon addition of second feeds of monomer or at lower initiator dose, while retaining narrow distributions. In terms of activity and controllability, the PZN-based catalysts were thus predominantly distinguished from not only a conventional iron complex [FeBr2(PPh3)2; Ph = C6H5] but also other hitherto known combinations...