DLVO理论
范德瓦尔斯力
化学物理
胶体
哈梅克常数
无量纲量
纳米颗粒
粒子(生态学)
工作(物理)
材料科学
纳米技术
热力学
化学
分子
物理化学
物理
范德瓦尔斯半径
有机化学
海洋学
地质学
作者
Doris Segets,Renata Marczak,Stefan Schäfer,Carolin Paula,Jan-Frederik Gnichwitz,Andreas Hirsch,Wolfgang Peukert
出处
期刊:ACS Nano
[American Chemical Society]
日期:2011-05-05
卷期号:5 (6): 4658-4669
被引量:101
摘要
The current work addresses the understanding of the stabilization of nanoparticles in suspension. Specifically, we study ZnO in ethanol for which the influence of particle size and reactant ratio as well as surface coverage on colloidal stability in dependence of the purification progress was investigated. The results revealed that the well-known ζ-potential determines not only the colloidal stability but also the surface coverage of acetate groups bound to the particle surface. The acetate groups act as molecular spacers between the nanoparticles and prevent agglomeration. Next to DLVO calculations based on the theory of Derjaguin, Landau, Verwey and Overbeek using a core-shell model we find that the stability is better understood in terms of dimensionless numbers which represent attractive forces as well as electrostatic repulsion, steric effects, transport properties, and particle concentration. Evaluating the colloidal stability in dependence of time by means of UV-vis absorption measurements a stability map for ZnO is derived. From this map it becomes clear that the dimensionless steric contribution to colloidal stability scales with a stability parameter including dimensionless repulsion and attraction as well as particle concentration and diffusivity of the particles according to a power law with an exponent of -0.5. Finally, we show that our approach is valid for other stabilizing molecules like cationic dendrons and is generally applicable for a wide range of other material systems within the limitations of vanishing van der Waals forces in refractive index matched situations, vanishing ζ-potential and systems without a stabilizing shell around the particle surface.
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