Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA.
J Chem Phys. 2017 Jun 14;146(22):224902. doi: 10.1063/1.4985568.
The complexation of mixtures of cationic and anionic polymers to produce complex-coacervate phases is a subject of fundamental importance to colloid and polymer science as well as to applications including drug delivery, sensing technologies, and bio-inspired adhesives. Unfortunately the theoretical underpinnings of complex coacervation are widely misunderstood and conceptual mistakes have propagated in the literature. Here, a simple symmetric polyelectrolyte mixture model in the absence of salt is used to discuss the salient features of the phase diagram, including the location of the critical point, binodals, and spinodals. It is argued that charge compensation by dimerization in the dilute region renders the phase diagram of an oppositely charged polyelectrolyte mixture qualitatively and quantitatively similar to that of a single-component symmetric diblock polyampholyte solution, a system capable of "self-coacervation." The theoretical predictions are verified using fully fluctuating field-theoretic simulations for corresponding polyelectrolyte and diblock polyampholyte models. These represent the first comprehensive, approximation-free phase diagrams for coacervate and self-coacervate systems to appear in the literature.
阳离子和阴离子聚合物混合物的络合作用产生复杂凝聚相，这是胶体和聚合物科学以及包括药物输送、传感技术和仿生粘合剂在内的应用领域的一个基本主题。不幸的是，复杂凝聚的理论基础被广泛误解，概念错误在文献中传播。在这里，使用简单的对称聚电解质混合物模型（无盐）来讨论相图的显著特征，包括临界点、双节点和旋节点的位置。有人认为，在稀溶液区域中通过二聚化进行的电荷补偿使得带相反电荷的聚电解质混合物的相图在定性和定量上与单一组分对称的两嵌段聚两性电解质溶液相似，这是一种能够“自凝聚”的体系。使用相应的聚电解质和两嵌段聚两性电解质模型的全涨落场论模拟验证了理论预测。这些是文献中首次出现的关于凝聚相和自凝聚相系统的全面、无近似的相图。
