氯化钕异丙醇合物/三异丁基铝催化剂活性中心的分离与聚合

研究了氯化钕异丙醇合物/三异丁基铝催化剂的配制方式对异戊二烯聚合和聚合产物特性的影响。 将催化剂的悬浊液分离得到清液和沉淀,分别进行聚合,并对沉淀进行了拉曼光谱表征。 结果表明,(Nd+Al)配制方式在室温和70 ℃下所得催化剂的清液均无活性,并且70 ℃下所得催化剂的沉淀也无活性。 (Nd+IP+Al)配制方式在任何条件下所得催化剂的各组分均有活性,推测该配制方式所得催化剂可能形成的是2种活性中心：(isoprenyl)2NdCl和(isoprenyl)NdCl2。 配制方式对聚异戊二烯的微观结构没有影响(96%左右),分离前的悬浮催化剂和沉淀催化剂所得聚异戊二烯均为高分子量(Mn＞100×104)和窄分子量分布(Mw/Mn＜2.0)的聚合物,但是分离后清液所得聚合物的分子量较低(Mn＜30×104),分子量分布很宽(Mw/Mn＞5.0)。

Separation and Polymerization of Active Species Using Neodymium Chloride Isopropanol Complex/ Triisobutylaluminium as Catalyst

The reaction product between NdCl3·3i-PrOH and Al(i-Bu)3 as catalysts was separated into a soluble and an insoluble part in hexane, and isoprene polymerization behaviors and characteristics of hexane-soluble and insoluble fractions were examined. The results indicated that the hexane-soluble fraction of the catalyst aging with the (Nd+Al) preformation had no activity at room temperature and at 70 ℃, and the catalytic precipitate obtained at 70 ℃had no active too. The catalysts with the (Nd+IP+Al) preparation pattern showed activity of polymerization at both room temperature and 70 ℃. We speculated that there are two catalyst active centers of (isoprenyl)2NdCl and (isoprenyl)NdCl2 in the polymerization system. The catalytic prepared methods had no effect on the microstructures of polyisoprene(about 96%). The molecular mass of the polyisoprenes obtained by the suspension catalyst and precipitate catalyst was high(Mn＞100×104) and the molecular mass distribution was narrow(Mw/Mn＜2.0), while the polyisoprene obtained by the clear solution catalyst had lower molecular mass(Mn＜30×104) and a very wide molecular mass distribution(Mw/Mn＞5.0).