We present structural and turbidimetric characterizations of aqueous dispersions of oppositely charged nanoparticles and polyelectrolytes that undergo complexation and flocculation to form particle-rich agglomerates over a wide range of polyelectrolyte and nanoparticle concentrations with varying polyelectrolyte sizes and persistence lengths. Compaction of nanoparticles in the polyelectrolyte–nanoparticle complexes, signified by decreasing internanoparticle spacing until they are brought in near-contact, is observed upon increasing screening of interparticle repulsion arising from adsorption of polyelectrolytes on the nanoparticle surfaces. We identify the ratio of charge borne by the polyelectrolytes and the nanoparticles as a key parameter dictating the compaction of nanoparticles into complexes as well as densification of complexes into agglomerates. Moreover, the emergence of turbidity in solution is shown to correlate with the initiation of nanoparticle compaction by polyelectrolytes but failing to describe further structural evolution of the complexes, emphasizing the need for alternate characterization techniques.

中文翻译：

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纳米粒子-聚电解质复合物的结构：聚电解质特性和电荷比的影响

我们展示了带相反电荷的纳米颗粒和聚电解质的水分散体的结构和浊度表征，这些水分散体经过络合和絮凝，在各种聚电解质和纳米颗粒浓度范围内形成富含颗粒的团聚体，聚电解质大小和持续时间各不相同。在聚电解质 - 纳米颗粒复合物中纳米颗粒的压实，通过减小内部颗粒间距直到它们接近接触，在增加对由聚电解质吸附在纳米颗粒表面上引起的颗粒间排斥的筛选时观察到。我们将聚电解质和纳米颗粒所携带的电荷比确定为决定纳米颗粒压实成复合物以及复合物致密化成团块的关键参数。此外，溶液中混浊的出现与聚电解质对纳米颗粒压实的启动有关，但未能描述复合物的进一步结构演变，强调需要替代表征技术。