We previously developed a method called carbanionic copolymerization-induced crystallization (CCPIC) to prepare alternating crystalline copolymers by adjusting the copolymer composition rather than by increasing the content of a certain stereochemical structure. In this work, eight new alternating crystalline copolymers were developed by regulating the substituent structure of conjugated dienes used in CCPIC. These types of conjugated dienes can achieve alternating growth with 1,1-diphenylethylene (DPE) and its derivatives (9-methylene-9H-thioxanthene, MTAE; 9,9-dimethyl-10-methylene-9,10-dihydroanthracene, MMAE) under neat conditions. When the substituents at the 2- or 3-position of the dienes change from 2-H/3-H (butadiene, BD) to 2-cyclopentyl/3-CH₃ (2-cyclopentyl-3-methyl-1,3-butadiene, MCPBD) and 2-cyclohexyl/3-CH₃ (2-cyclohexyl-3-methyl-1,3-butadiene, MCHBD) with greater steric hindrance, the alternating copolymers DPE/MTAE/MMAE-alt-MCPBD/MCHBD exhibit crystallization characteristics. DPE (without a bridge structure)-alt-MCPBD/MCHBD exhibits low crystallinity, and the crystallinity of MMAE (with a bridge structure containing two methyl substituents)-alt-MCPBD/MCHBD decreases with the increase in the size of the substituents. This indicates that the structure of DPE and its derivatives affects the aggregation structure of these alternating polymers. Interestingly, DPE and its derivatives (MTAE and MMAE) do not have chiral carbon atoms or stereoisomers in their polymer chains. The amorphous-to-crystalline transition of the polymer was achieved by changing the substituent structure of the dienes and DPE derivatives used in alternating copolymerization. Therefore, the crystallization of these crystalline polymers in CCPIC can be attributed to the steric hindrance effect brought about by the comonomer structure rather than just the stereoregularity of the monomer units in the chain.

中文翻译：

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通过碳离子共聚诱导结晶合成的交替结晶共聚物的取代基调控


我们之前开发了一种称为碳离子共聚诱导结晶 （CCPIC） 的方法，通过调整共聚物组成而不是增加某种立体化学结构的含量来制备交替结晶共聚物。在这项工作中，通过调节 CCPIC 中使用的共轭二烯的取代基结构，开发了 8 种新的交替结晶共聚物。这些类型的共轭二烯可以在整洁的条件下与 1,1-二苯乙烯 （DPE） 及其衍生物（9-亚甲基-9H-噻杂蒽，MTAE;9,9-二甲基-10-亚甲基-9,10-二氢蒽，MMAE）实现交替生长。当二烯的 2 位或 3 位取代基从 2-H/3-H（丁二烯，BD）变为 2-环戊基/3-CH₃（2-环戊基-3-甲基-1,3-丁二烯，MCPBD）和 2-环己基/3-CH₃（2-环己基-3-甲基-1,3-丁二烯，MCHBD）时，交替共聚物 DPE/MTAE/MMAE-alt-MCPBD/MCHBD 表现出结晶特性。DPE（无桥结构）-alt-MCPBD/MCHBD 表现出低结晶度，MMAE（具有包含两个甲基取代基的桥结构）-alt-MCPBD/MCHBD 的结晶度随着取代基尺寸的增加而降低。这表明 DPE 及其衍生物的结构会影响这些交替聚合物的聚集结构。有趣的是，DPE 及其衍生物（MTAE 和 MMAE）的聚合物链中没有手性碳原子或立体异构体。聚合物的无定形到结晶转变是通过改变交替共聚中使用的二烯烃和 DPE 衍生物的取代基结构来实现的。 因此，这些结晶性聚合物在 CCPIC 中的结晶可以归因于共聚单体结构带来的空间位阻效应，而不仅仅是链中单体单元的立体规则性。