Leermakers F A M, Ruiz-Martínez L, Stoyanov S D, van der Gucht J
Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, Wageningen 6708 WE, the Netherlands.
Food, Chemical, and Biotechnology cluster, Singapore Institute of Technology, 10 DoverDrive, Singapore 138683, Singapore.
J Phys Chem B. 2025 Jul 3;129(26):6632-6645. doi: 10.1021/acs.jpcb.5c01284. Epub 2025 Jun 19.
Quasi-ternary dextran-water-polyethylene glycol (D-W-PEG) systems can undergo a segregative phase transition from a homogeneous to two-phase state with one phase enriched in dextran, the other in PEG, and both phases typically dominated by the spectator-like water component. The relation between the driving forces and the resulting phase behavior for such aqueous two-phase systems (ATPSs) is systematically studied with a Scheutjens-Fleer self-consistent field (SF-SCF) theory. We consider both the repulsive interactions between the polymeric species (the major driving force) and the solvent quality disparity (the minor driving force). In a narrow parameter range, when the major driving force is very weak, a closed-loop two-phase region with two critical points may be found. However, in more realistic parameter settings, an ATPS has an'open' binodal with a single critical point. We report on the volume ratio, the composition of the phases, (structural) parameters of the interface, such as the width, and the interfacial tension, as a function of the (average) water fraction in the system. We show that the volume-management strategy influences the phase diagram when polymers are polydisperse. By fitting a set of experimental phase diagrams, SF-SCF model parameters for D-W-PEG systems are established, which will be used in future to underpin experiments for these systems.
准三元葡聚糖-水-聚乙二醇（D-W-PEG）体系可经历从均相到两相状态的偏析相转变，其中一相富含葡聚糖，另一相富含聚乙二醇，且两相通常都以类似旁观者的水组分占主导。利用Scheutjens-Fleer自洽场（SF-SCF）理论系统研究了此类水两相体系（ATPSs）中驱动力与所得相行为之间的关系。我们考虑了聚合物物种之间的排斥相互作用（主要驱动力）和溶剂质量差异（次要驱动力）。在一个狭窄的参数范围内，当主要驱动力非常弱时，可能会发现具有两个临界点的闭环两相区域。然而，在更实际的参数设置中，ATPS具有一个具有单个临界点的“开放”双节线。我们报告了体系中体积比、相组成、界面的（结构）参数（如宽度）以及界面张力随（平均）水分数的变化情况。我们表明，当聚合物为多分散时，体积管理策略会影响相图。通过拟合一组实验相图，建立了D-W-PEG体系的SF-SCF模型参数，这些参数将在未来用于支持这些体系的实验。
