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本工作研究了β-二酮类希土螯合物与三烷基铝组成的均相体系对丁二烯定向聚合的催化活性及一些聚合规律。实验结果表明下列希土螯合物与三乙基铝组合时都具有使丁二烯进行顺式-1,4定向聚合的催化活性:NdB_3;NdB;NdBTA;NdTTA;PrB_3;PrB;PrBTA;PrTTA;YB_3;YBTA 以及 LaBTA 等。这些均相催化体系的活性远比非均相希土氯化物体系的高。在一定的催化剂浓度范围内,催化活性随着Al/希土及希土/丁(克分子比)的增高而增大。聚合反应速率对单体浓度呈一级关系,对希土螯合物浓度也近似呈 一级关系,并呈现一诱导期。丁二烯在 NdB_3-Al(C_2H_5)_3体系中聚合的总活化能为 13±0.5千卡/克分子。研究不同希土元素的这些螯合物表明同一元素的不同螯合物体系的聚合反应速率和聚合物链结构都没有显著的差别。但不同希土元素的同一整合物体系的聚合活性相差较大,含有镨和钕螯合物体系的活性比其他体系大。由这些均相催化体系所得聚丁二烯的1,2链节含量不超过1％,都不含或含很少量凝胶,聚合物的[η]随着Al/希土(克分子比)以及希土/丁(克分子比)的增大而降低,[η]可以从 4—5降至 1以下。Al(i-C_4H_9)_3也能与这些螯合物组成活性催化体系,但活性很低。Al(C_2H_5)_2Cl则不能与这些螯合物构成活性催化体系。
This work studied the catalytic activity and some polymerization rules of the homopolymer system of β-diketono-chelate and trialkylaluminum for directional polymerization of butadiene. The experimental results show that the following rare earth chelate complexes with triethylaluminum have the catalytic activity of butadiene cis-1,4 orientation polymerization: NdB_3; NdB; NdBTA; NdTTA; PrB_3; PrB; PrBTA; PrTTA ; YB_3; YBTA and LaBTA and so on. These homogeneous catalytic systems are far more active than heterogeneous rare earth chloride systems. At a certain range of catalyst concentration, the catalytic activity increases with the increase of Al / rectorite and rectorite / rhodium molar ratio. The polymerization rate showed a first-order relationship with the monomer concentration, and also had a first-order relationship with the concentration of the chelate of the laterite and showed an induction period. The total activation energy of butadiene polymerized in NdB_3-Al (C_2H_5) _3 system is 13 ± 0.5 kcal / mol. The study of these chelates of different rare earth elements shows that there is no significant difference in the polymerization rate and the polymer chain structure for different chelate systems of the same element. However, the activity of the same monolithic system with different rare earth elements varies greatly, and the system containing praseodymium and neodymium chelate is more active than other systems. The polybutadienes obtained from these homogeneous catalysis systems contain no more than 1% of 1,2-linkages and contain no or very small amounts of gels. The [η] of the polymers increases with increasing Al / ) And the ratio of rehield / mole (mole ratio), [η] can be reduced from 4-5 to below 1. Al (i-C_4H_9) _3 can also form an active catalytic system with these chelates, but the activity is very low. Al (C_2H_5) _2Cl can not form an active catalytic system with these chelates.