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定向聚合所用的 Ziegler 型催化剂,包含过渡金属卤化物及Ⅰ、Ⅱ或Ⅲ族金属有机化合物二组份。它们间的反应对定向聚合具有决定性的作用。近年来不少人对此进行了研究,其中研究得较多的是烷基铝与四氯化钛的反应。研究方法之一是测定催化剂反应时过渡金属的价态。价态与聚合的活性有一定的关系。Friedlander 曾指出,乙烯在室温用三异丁基铝及四氯化钛聚合时,催化剂的最大活性在钛为三价时;Ludlum 则认为,乙烯在80℃聚合时,最大的活性在钛为二价时。Kern 曾指出,苯乙烯在25℃聚合时,当二价钛与三价钛之比为1:1
Ziegler-type catalyst for directional polymerization comprises a transition metal halide and a Group I, II or III organometallic compound. The reaction between them plays a decisive role in directional polymerization. In recent years, many people have carried out research on this, which is the most studied aluminum alkyl and titanium tetrachloride reaction. One of the research methods is to determine the valence of the transition metal during the reaction of the catalyst. Valence and polymerization activity have a certain relationship. Friedlander has pointed out that when ethylene is polymerized with triisobutylaluminum and titanium tetrachloride at room temperature, the maximum activity of the catalyst is when the titanium is trivalent; Ludlum suggests that the maximum activity of ethylene when polymerized at 80 & lt; 0 & When price. Kern once pointed out that when styrene is polymerized at 25 ° C, when the ratio of divalent titanium to trivalent titanium is 1: 1