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如众周知,典型的齐格勒-纳达(Ziegler-Natta)定向聚合催化剂是多相系統。由于催化系統的这一特点,使得在聚合及聚合物純制过程中,出現了一系列理論和实际問題,其中值得一提的是:难以从聚合物中洗出残存的催化剂以及对聚合过程本身研究所带来的困难等。为了克服非均相定向聚合催化剂的这些缺点,近年来出现了不少有关均相定向聚合方面的研究工作,因为采用均相絡合物催化系統不只可以大大减少催化剂的用量,而且可以简化所得聚合物的純化过程。虽然目前有关均相定向聚合的工作,文献上有过不少的报导,但按其引发的性质来說,大致可分为两类:一
As is well known, a typical Ziegler-Natta directional polymerization catalyst is a heterogeneous system. Due to this feature of the catalytic system, a series of theoretical and practical problems have arisen in the polymerization and polymer purification processes, of which it is worth mentioning that it is difficult to wash out the remaining catalyst from the polymer and to separate the polymerization process itself The difficulties caused by the research. In order to overcome these shortcomings of heterogeneous directional polymerization catalysts, there have been many researches on homogeneous polymerization in recent years, because the use of homogeneous complex catalyst system not only can greatly reduce the amount of catalyst, but also can simplify the resulting polymerization Purification process. Although there are a lot of reports on the work of homogeneous directional aggregation at present, according to the nature of its initiation, it can be roughly divided into two types: one