A SiO₂/MgCl₂-bisupported Ziegler–Natta-type catalyst is studied in gas-phase ethylene/1-butene copolymerization. With a minimal amount of alkylaluminum required to activate the catalyst, polymerization kinetics is profoundly affected by the dosage of it. High dosage of alkylaluminum retards the polymerization but does not kill the catalyst. Through a comprehensive characterization on the samples by differential scanning calorimetry, crystallization elution fractionation, thermal gradient interaction chromatography, cross-fractionation chromatography, and nuclear magnetic resonance, it has been shown that alkylaluminum also alters the short-chain branching distribution (SCBD) of the copolymer but barely affects the total comonomer incorporation. It is proposed that alkylaluminum alters the active species from producing statistical copolymer chains to producing block polymer chains with C4-enriched and C4-scattered segments. It provides an example of a bimetallic structure of active species as well as an approach to tailor SCBD between a statistical copolymer and block copolymer bearing C4-enriched and C4-scattered segments.

中文翻译：

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工程聚（乙烯-共-1-丁烯）通过调制由烷基铝的活性物质

SiO ₂ / MgCl ₂在气相乙烯/ 1-丁烯共聚中研究了双支撑的齐格勒-纳塔型催化剂。用最少量的烷基铝来活化催化剂，聚合动力学受其用量的影响很大。高剂量的烷基铝会延迟聚合反应，但不会杀死催化剂。通过差示扫描量热法，结晶洗脱分级分离，热梯度相互作用色谱，交叉分馏色谱和核磁共振对样品进行全面表征，结果表明烷基铝还改变了样品的短链支化分布（SCBD）。共聚物，但几乎不影响共聚单体的总掺入量。提出烷基铝改变活性物种，从产生统计共聚物链到产生具有富含C 4和C 4分散链段的嵌段聚合物链。它提供了一个活性物种双金属结构的例子，以及在带有C4富集和C4分散链段的统计共聚物和嵌段共聚物之间调整SCBD的方法。