Abstract

The cationic polymerization of butadiene under the action of catalytic systems based on diethylaluminum chloride (AlEt₂Cl) in combination with tertiary alkyl halides (AHs) such as tert-butyl chloride, tert-butyl bromide, and 2-chloro-2-methylbutane is found to be an efficient method for the preparation of fully soluble butadiene polymers at a technologically convenient process temperature of 20°C. It is shown that with an increase in the duration of butadiene polymerization process, the weight-average molecular weights and polydispersity of the polymer increase significantly with a simultaneous decrease in the unsaturation of polybutadiene, which is associated with the transfer reaction of the growing chain to the double bond of the polymer during polymerization. A ¹³C NMR spectral study showed that the macromolecules of polybutadiene synthesized on the AlEt₂Cl–tert-butyl chloride catalytic system consist mainly of 1,4-trans units and contain two types of initial tert-butyl units and two types of end chlorine-containing units formed as a result of the transfer reaction of the growing chain to tert-butyl chloride. Based on the data of ¹³C NMR spectra of polybutadiene, a method for calculating butadiene conversion during polymerization is developed, and a mechanism of the process of cationic polymerization of butadiene is proposed. It is shown that the synthesized “cationic” polybutadiene is characterized by high film-forming properties and can be a promising component in the production of paints and varnishes.

中文翻译：

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基于二乙基氯化铝的阳离子催化体系合成低分子量丁二烯聚合物

摘要

丁二烯在基于二乙基氯化铝（AlEt ₂ Cl）和叔烷基卤（AHs）如叔丁基氯、叔-丁基溴和 2-氯-2-甲基丁烷被发现是在 20°C 的技术便利工艺温度下制备完全可溶的丁二烯聚合物的有效方法。结果表明，随着丁二烯聚合过程持续时间的增加，聚合物的重均分子量和多分散性显着增加，同时聚丁二烯的不饱和度降低，这与增长的链向转移反应有关聚合过程中聚合物的双键。13 C NMR谱研究表明，在AlEt ₂ Cl-叔丁基氯催化体系上合成^的聚丁二烯大分子主要由1,4-反式单元并包含两种类型的初始叔丁基单元和两种类型的末端含氯单元，这些单元是由于生长链向叔丁基氯的转移反应而形成的。基于聚丁二烯的¹³ C NMR光谱数据，建立了聚合过程中丁二烯转化率的计算方法，并提出了丁二烯阳离子聚合过程的机理。结果表明，合成的“阳离子”聚丁二烯具有高成膜性能，可以成为油漆和清漆生产中有前途的成分。