Complex coacervation is a widely utilized technique for effecting phase separation, though predictive understanding of molecular-level details remains underdeveloped. Here, we couple coarse-grained Monte Carlo simulations with experimental efforts using a polypeptide-based model system to investigate how a comb-like architecture affects complex coacervation and coacervate stability. Specifically, the phase separation behavior of linear polycation-linear polyanion pairs was compared to that of comb polycation-linear polyanion and comb polycation-comb polyanion pairs. The comb architecture was found to mitigate cooperative interactions between oppositely charged polymers, as no discernible phase separation was observed for comb-comb pairs and complex coacervation of linear-linear pairs yielded stable coacervates at higher salt concentration than linear-comb pairs. This behavior was attributed to differences in counterion release by linear vs. comb polymers during polyeletrolyte complexation. Additionally, the comb polycation formed coacervates with both stereoregular poly(L-glutamate) and racemic poly(D,L-glutamate), whereas the linear polycation formed coacervates only with the racemic polyanion. In contrast, solid precipitates were obtained from mixtures of stereoregular poly(L-lysine) and poly(L-glutamate). Moreover, the formation of coacervates from cationic comb polymers incorporating up to ∼90% pendant zwitterionic groups demonstrated the potential for inclusion of comonomers to modulate the hydrophilicity and/or other properties of a coacervate-forming polymer. These results provide the first detailed investigation into the role of polymer architecture on complex coacervation using a chemically and architecturally well-defined model system, and highlight the need for additional research on this topic.

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梳状结构对复杂凝聚的影响

复杂凝聚法是实现相分离的一种广泛使用的技术，尽管对分子水平细节的预测性理解仍不完善。在这里，我们将粗粒度的蒙特卡洛模拟与基于多肽的模型系统的实验工作相结合，以研究梳状结构如何影响复杂的凝聚层和凝聚层稳定性。具体而言，将线性聚阳离子-线性聚阴离子对与梳状聚阳离子-线性聚阴离子和梳状聚阳离子-梳状聚阴离子对的相分离行为进行了比较。发现梳状结构可减轻带相反电荷的聚合物之间的协同相互作用，因为没有观察到梳-梳对的可分辨相分离，并且线性-线性对的复杂凝聚在盐浓度比线性-梳对更高的情况下会产生稳定的凝聚层。此行为归因于线性抗衡离子释放的差异与聚电解质络合过程中的梳状聚合物形成对比。另外，梳形聚阳离子与立构规整的聚（L-谷氨酸）和外消旋聚（D，L-谷氨酸）两者形成凝聚层，而线性聚阳离子仅与外消旋聚阴离子形成凝聚层。相反，固体沉淀物是从立构规整的聚L-赖氨酸和聚L的混合物中获得的。-谷氨酸）。而且，由掺入高达约90％的两性离子侧基的阳离子梳形聚合物形成凝聚层证明了包含共聚单体以调节形成凝聚层的聚合物的亲水性和/或其他性能的潜力。这些结果提供了使用化学和结构明确定义的模型系统对聚合物结构在复杂凝聚中的作用进行的首次详细研究，并强调了对此主题进行其他研究的必要性。