Isospecific Polymerization of Propylene By ansa-Zirconocene Diamide Compound Cocatalyzed by Mao
Isospecific Polymerization of Propylene By ansa-Zirconocene Diamide Compound Cocatalyzed by Mao
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毛助催化柄型二茂锆二酰胺化合物同构聚合丙烯
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
Ghil Nam Hwang
中科院分区：
文献类型：
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作者：
I. Kim;Ghil Nam Hwang
摘要研究了甲基铝氧烷(MAO)助催化外消旋乙烯-1，2-双(1-吲基)锆双(二甲酰胺)[RAc-(EBI)Zr(NMe2)2(RAC-1)]引发丙烯聚合的动力学。通过改变不同的实验参数考察了RAC-1/MAO催化剂与RAC-(EBI)ZrCl2(RAC-2)/MAO催化剂的聚合行为，这是由于每种茂金属与MAO反应生成阳离子活性物质的过程不同所致。当[Al]/[Zr]为137.1μM，聚合温度为30℃时，RAc-1/MAO催化剂的活性最高。在很低的MAO浓度下，RAc-1/MAO催化剂的活性可以忽略不计，这可能是由于阳离子活性物种的不稳定所致。在30℃时，RAC-1/MAO催化剂生成的聚合物的介五值在82.8%~89.7%之间。当聚合温度高于60℃时，RAC-1/MAO催化剂失去了立体基性质。
Abstract The kinetics of propylene polymerization initiated by racemic ethylene-1,2-bis(1-indenyl) zirconium bis(dimethylamide) [rac-(EBI) Zr(NMe2)2(rac-1)] cocatalyzed by methylaluminoxane (MAO) were studied. The polymerization behaviors of rac-1/MAO catalyst investigated by changing various experimental parameters are quite different from those of rac-(EBI) ZrCl2 (rac-2)/MAO catalyst, due to the differences in the generation procedure of cationic actives species of each metallocene by the reaction with MAO. The activity of rac-1/MAO catalyst showed maximum when [Al]/[Zr] is around 2000, when [Zr] is 137.1 μM, and when polymerization temperature is 30°C. The negligible activity of rac-1/MAO catalyst at a very low MAO concentration seems to be caused by the instability of the cationic active species. The meso pentad values of polymers produced by rac-1/MAO catalyst at 30°C are in the range of 82.8% to 89.7%. The rac-1/MAO catalyst lost stereorigid character at the polymerization temperature above 60°C. Th...