The Sequence of a Step-Growth Copolymer Can Be Influenced by Its Own Persistence Length
The Sequence of a Step-Growth Copolymer Can Be Influenced by Its Own Persistence Length
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逐步增长共聚物的序列可能受到其自身持续长度的影响
DOI：
10.1021/acs.jpcb.1c00873
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
DuBay, Kateri H.
中科院分区：
文献类型：
--
作者：
Zhang, Zhongmin;DuBay, Kateri H.
合成的共聚物序列仍然难以控制，即使是简单的一锅法、基于溶液的共聚也有一些尚未完全了解的特征。在以前的溶液分步生长共聚模拟中，我们证明了A型和B型单体之间的吸引力的微小变化可以通过新生低聚物的加长引发的紧急聚集和相分离来显著影响共聚序列。在这里，我们研究了共聚物的几何构型的一个方面─它的柔韧性─如何调节这些影响。我们的模拟表明，随着链刚性的增加，聚合诱导聚集体内的链排列开始，并证明这种排列可以影响所产生的共聚序列。对于持久性长度为≥10的共聚聚合物，相同类型的单体之间适度的∼kBT非键合吸引力会产生特征长度的A和B嵌段，并导致多分散性指数快速增长、达到峰值，然后随着反应的进行而减小。这些结果表明，对于单体间吸引力和物理上现实的灵活性变化不大的共聚体系，初生共聚物的持续长度可以影响其自身的顺序。
Synthetic copolymer sequences remain challenging to control, and there are features of even simple one-pot, solution-based copolymerizations that are not yet fully understood. In previous simulations on step-growth copolymerizations in solution, we demonstrated that modest variations in the attractions between type A and B monomers could significantly influence copolymer sequence through an emergent aggregation and phase separation initiated by the lengthening of nascent oligomers. Here we investigate how one aspect of a copolymer’s geometry─its flexibility─can modulate those effects. Our simulations show the onset of strand alignment within the polymerization-induced aggregates as chain stiffness increases and demonstrate that this alignment can influence the resulting copolymer sequences. For less flexible copolymers, with persistence lengths ≥10 monomers, modest nonbonded attractions of ∼kBTbetween monomers of the same type yield A and B blocks of a characteristic length and result in a polydispersity index that grows rapidly, peaks, and then diminishes as the reaction proceeds. These results demonstrate that for copolymer systems with modest variations in intermonomer attractions and physically realistic flexibilities a nascent copolymer’s persistence length can influence its own sequence.