Effect of Nanoparticles on the Interfacial Properties of Liquid/Liquid and Liquid/Air Surface Layers

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• 作者：Francesca Ravera ; Eva Santini ; Giuseppe Loglio ; Michele Ferrari ; Libero Liggieri
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：October 5, 2006
• 年：2006
• 卷：110
• 期：39
• 页码：19543 - 19551
• 全文大小：163K
• 年卷期：v.110,no.39(October 5, 2006)
• ISSN：1520-5207

文摘

An investigation is reported on the interfacial properties of nanometric colloidal silica dispersions in thepresence of a cationic surfactant. These properties are the result of different phenomena such as the particleattachment at the interface and the surfactant adsorption at the liquid and at the particle interfaces. Since thelatter strongly influences the hydrophobicity/lipophilicity of the particle, i.e., the particle affinity for the fluidinterfacial environment, all those phenomena are closely correlated. The equilibrium and dynamic interfacialtensions of the liquid/air and liquid/oil interfaces have been measured as a function of the surfactant andparticle concentration. The interfacial rheology of the same systems has been also investigated by measuringthe dilational viscoelasticity as a function of the area perturbation frequency. These results are then crossedwith the values of the surfactant adsorption on the silica particles, indirectly estimated through experimentsbased on the centrifugation of the dispersions. In this way it has been possible to point out the mechanismsdetermining the observed kinetic and equilibrium features. In particular, an important role in the mixed particle-surfactant layer reorganization is played by the Brownian transport of particles from the bulk to the interfaceand by the surfactant redistribution between the particle and fluid interface.