Li Nan K, Fuss William H, Tang Lei, Gu Renpeng, Chilkoti Ashutosh, Zauscher Stefan, Yingling Yaroslava G
Department of Materials Science and Engineering, North Carolina State University, 911 Partners Way, Raleigh, NC 27695, USA.
Department of Mechanical Engineering and Materials Science, Duke University, 144 Hudson Hall, Durham, NC 27708, USA.
Soft Matter. 2015 Nov 14;11(42):8236-45. doi: 10.1039/c5sm01742d.
Self-assembly processes of polyelectrolyte block copolymers are ubiquitous in industrial and biological processes; understanding their physical properties can also provide insights into the design of polyelectrolyte materials with novel and tailored properties. Here, we report systematic analysis on how the ionic strength of the solvent and the length of the polyelectrolyte block affect the self-assembly and morphology of the polyelectrolyte block copolymer materials by constructing a salt-dependent morphological phase diagram using an implicit solvent ionic strength (ISIS) method for dissipative particle dynamics (DPD) simulations. This diagram permits the determination of the conditions for the morphological transition into a specific shape, namely vesicles or lamellar aggregates, wormlike/cylindrical micelles, and spherical micelles. The scaling behavior for the size of spherical micelles is predicted, in terms of radius of gyration (R(g,m)) and thickness of corona (Hcorona), as a function of solvent ionic strength (c(s)) and polyelectrolyte length (NA), which are R(g,m) ∼ c(s)(-0.06)N(A)(0.54) and Hcorona ∼ c(s)(-0.11)N(A)(0.75). The simulation results were corroborated through AFM and static light scattering measurements on the example of the self-assembly of monodisperse, single-stranded DNA block-copolynucleotides (polyT50-b-F-dUTP). Overall, we were able to predict the salt-responsive morphology of polyelectrolyte materials in aqueous solution and show that a spherical-cylindrical-lamellar change in morphology can be obtained through an increase in solvent ionic strength or a decrease of polyelectrolyte length.
聚电解质嵌段共聚物的自组装过程在工业和生物过程中普遍存在；了解它们的物理性质也有助于设计具有新颖和定制性质的聚电解质材料。在此，我们通过使用耗散粒子动力学（DPD）模拟的隐式溶剂离子强度（ISIS）方法构建盐依赖的形态相图，系统分析了溶剂的离子强度和聚电解质嵌段的长度如何影响聚电解质嵌段共聚物材料的自组装和形态。该相图允许确定形态转变为特定形状的条件，即囊泡或层状聚集体、蠕虫状/圆柱形胶束和球形胶束。预测了球形胶束尺寸的标度行为，以回转半径（R(g,m)）和冠层厚度（Hcorona）表示，作为溶剂离子强度（c(s)）和聚电解质长度（NA）的函数，分别为R(g,m) ∼ c(s)(-0.06)N(A)(0.54) 和Hcorona ∼ c(s)(-0.11)N(A)(0.75)。通过对单分散单链DNA嵌段共多核苷酸（polyT50-b-F-dUTP）自组装实例的原子力显微镜（AFM）和静态光散射测量，证实了模拟结果。总体而言，我们能够预测聚电解质材料在水溶液中的盐响应形态，并表明通过增加溶剂离子强度或减少聚电解质长度，可以实现形态从球形到圆柱形再到层状的变化。
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