Self-Assembly of Star-Polyelectrolytes in Various Solution Conditions
Self-Assembly of Star-Polyelectrolytes in Various Solution Conditions
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DOI：
10.1021/acs.macromol.3c01580
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发表时间：
2023-12
期刊：
影响因子：
5.5
通讯作者：
Jun-Jie Zhang;Bin Li
中科院分区：
文献类型：
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作者：
Jun-Jie Zhang;Bin Li
星形聚电解质的复杂拓扑结构为控制溶液中的自组装行为提供了更大的可能性，从而获得丰富的形貌。因此，我们研究了电荷驱动的自组装带相反电荷的星形聚电解质与不同的臂数在溶液中的各种离子强度和温度进行粗粒度的分子动力学模拟。形态相图的构建，并获得了丰富多样的形态结构与单分子胶束的顺序，松散的聚集体，无定形聚集体，交联结构的溶液离子强度降低。自组装的结构转变取决于带相反电荷的基团之间的静电吸引力和带相同电荷的基团之间的长程排斥力的强度，这增加了进一步聚集的能垒。各种相互作用的竞争导致聚阳离子和聚阴离子的交替连接。增加臂数或降低温度也会表现出这种转变的趋势，这分别会增加局域电荷密度和降低热涨落。平均力势分析表明，配位热力学和结构转变主要取决于离子强度。无定形和交联聚集体的形成途径显示出类似的初始短蠕虫状结构与一些交联，然后，观察到不同的途径，由于多个自由能极小值的蠕虫状结构的关联。模拟结果有助于理解星形聚电解质在不同条件下的自组装机理，并为制备具有潜在应用价值的目标聚集体形态提供参考。
The topological complexity of star-polyelectrolytes provides a larger probability for controlling self-assembly behaviors in solution to obtain plentiful morphologies. Therefore, we study the charge-driven self-assembly of oppositely charged star-polyelectrolytes with different arm numbers in solution with various ionic strengths and temperatures by performing coarse-grained molecular dynamics simulations. Morphological phase diagrams are constructed, and a rich variety of morphological structures are obtained with a sequence of unimolecular micelle, loose aggregate, amorphous aggregate, and cross-linked structure as the solution ionic strength decreases. The structural transitions of self-assembly depend on both the strength of electrostatic attraction between oppositely charged groups and long-range repulsion between the same charged groups, which increases the energy barriers for further aggregation. The competition of various interactions results in the alternating connection of polycations and polyanions. The tendency of the transition is also exhibited by increasing the arm numbers or lowering the temperatures, which increase the local charge density and reduce the thermal fluctuation, respectively. The potential of mean force analyses reveals that the complexation thermodynamics and structural transitions between opposite star-polyelectrolyte depend mainly on ionic strength. The formation pathways of amorphous and cross-linked aggregates show similar initial short worm-like structures with some cross-links; then, the different pathways are observed due to multiple free energy minima for the association of the worm-like structures. The simulation results may help to understand the self-assembly mechanism of star-polyelectrolytes in various conditions and provide useful references for fabricating target aggregate morphologies in potential applications.