Space-limited living species provide new insight into the regulation of the microstructure of isoprene units in alternating copolymers composed of isoprene (Ip) and 1,1-bis(4-dimethylsilylphenyl)ethylene (DPE-2SiH) using living anionic polymerization (LAP) modified with additives. It was found that suitable modifiers, such as sodium alkoxide (RONa), led to nearly 80% cis 1,4-addition of the isoprene units, while addition of potassium alkoxide (ROK) resulted in nearly 70% trans 1,4-addition. Through analysis, we know that the additives influence the angles between two subterminal benzene rings, and promote the regulatory effect of the space-limited living species on the cis and trans isoprene units. The larger the angle between two subterminal benzene rings, the more favourable are the conditions for addition polymerization in this form of microstructure. The copolymerization mechanism was investigated with the assistance of density functional theory (DFT) with Gaussian 09 and the corresponding characteristics of copolymers were determined with SEC, ¹H NMR, ¹³C NMR and MALDI-TOF MS techniques. Due to the living features of LAP, this method can be employed as a key control of the copolymer chain sequence and microstructure at the same time.

中文翻译：

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通过阴离子聚合中“空间受限”的生物物种调节交替共聚物中异戊二烯单元的顺式和反式微结构

有限空间的生物物种提供了利用活性阴离子聚合（LAP）来调节由异戊二烯（Ip）和1,1-双（4-二甲基甲硅烷基苯基）乙烯（DPE-2SiH）组成的交替共聚物中异戊二烯单元微观结构的新见解用添加剂改性。发现合适的改性剂，例如醇钠（RONa），导致异戊二烯单元的顺式1,4-加成近80％，而醇钾（ROK）的加入导致反式1,4-加成近70％。通过分析，我们知道添加剂会影响两个亚末端苯环之间的角度，并促进空间受限的生物物种对顺式和反式的调节作用。异戊二烯单位。两个亚末端苯环之间的角度越大，以这种形式的微结构进行加聚的条件越有利。借助密度泛函理论（DFT）和高斯09对共聚机理进行了研究，并通过SEC，¹ H NMR，¹³ C NMR和MALDI-TOF MS技术测定了共聚物的相应特性。由于LAP的活性特征，该方法可同时用作共聚物链序列和微观结构的关键控制。