非极性纳米粒子的胶体稳定性：配体长度的作用
On the colloidal stability of apolar nanoparticles: The role of ligand length
摘要：
无机纳米颗粒核通常用有机配体包覆以使它们可分散在非极性溶剂中。然而，配体壳对整个混合颗粒的胶体稳定性的影响还没有完全了解。特别地，不知道非极性烷基配体链的长度如何影响纳米颗粒分散体的抗团聚稳定性。本文采用小角X射线散射和分子动力学模拟研究了在癸烷溶剂中，金纳米粒子和12 ~ 18个碳原子的烷基乙氧基化物钝化的硒化镉纳米粒子之间的相互作用。我们发现，增加配体的长度增加胶体的稳定性在核心为主的政权，但减少它在配体为主的政权。这种意想不到的反转连接到从配体到核心主导的团聚时，在恒定的配体长度的核心直径增加的过渡。我们的研究结果提供了一个微观图片的力量，确定非极性纳米粒子的胶体稳定性，并解释了为什么经典的胶体理论失败。
英文摘要：
Inorganic nanoparticle cores are often coated with organic ligands to render them dispersible in apolar solvents. However, the effect of the ligand shell on the colloidal stability of the overall hybrid particle is not fully understood. In particular, it is not known how the length of an apolar alkyl ligand chain affects the stability of a nanoparticle dispersion against agglomeration. Here, Small-Angle X-ray Scattering and molecular dynamics simulations have been used to study the interactions between gold nanoparticles and between cadmium selenide nanoparticles passivated by alkanethiol ligands with 12 to 18 carbons in the solvent decane. We find that increasing the ligand length increases colloidal stability in the core-dominated regime but decreases it in the ligand-dominated regime. This unexpected inversion is connected to the transition from ligand- to core-dominated agglomeration when the core diameter increases at constant ligand length. Our results provide a microscopic picture of the forces that determine the colloidal stability of apolar nanoparticles and explain why classical colloid theory fails.
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