good yields. The bulky aryl groups on the Rh complex were essential to achieving high initiator efficiency, whereas the bulky substituents on aryl isocyanides were required for the formation of high molecular weight polymers. The living nature of the present system was confirmed by kinetic studies as well as the formation of block copolymers. The polymerization rate was dependent not on the concentration
良好定义arylrhodium络合物的Rh(AR)(NBD)(PPH 3)(AR =我2 ç 6 ħ 3,2,4,6-
镨我3 C 6 H 2,2 -PhC 6 H 4,2 -Me-1-
萘基,9-
蒽基,C(Ph)CPh 2;由[Rh(nbd)Cl] 2与LiAr和PPh 3反应制备的nbd =
2,5-降冰片二烯)在PPh 3存在下,有效地引发了邻位具有大取代基的芳基
异氰酸酯的活性聚合以高收率得到具有窄多分散指数的聚
异氰酸酯。Rh络合物上的大体积芳基对于实现高
引发剂效率是必不可少的,而芳基异
氰化物上的大体积取代基是形成高分子量聚合物所必需的。通过动力学研究以及嵌段共聚物的形成证实了本系统的活性性质。聚合速率不取决于单体的浓度,而是取决于PPh 3的浓度。