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Silica Nanoparticle Monolayers on Macroion Modified Surface: Formation Mechanism and Stability

Abstract

Even though silica nanoparticles and their monolayers find a broad field of applications, only few studies providing the quantitative description of silica nanoparticle deposition at solid/liquid interfaces have been reported in the literature. Given the deficit of reliable experimental data, the goal of this work is to acquire thorough physicochemical characteristics of amorphous silica nanoparticle deposition. The adsorption/desorption measurements performed in our studies allowed to determine the influence of the particle structure on the initial rate of the monolayer formation and to develop an efficient method for obtaining uniform monolayers of amorphous nanoparticles of high and well-controlled density. Silica nanoparticle monolayers of controlled coverage were formed on macroion (PAH)-modified mica. The size of the particles determined by dynamic light scattering (DLS), atomic force microscopy (AFM) and scanning electron microscopy (SEM) was equal to 28 nm. The electrophoretic mobility and the zeta potential of particles were also determined as a function of ionic strength and pH. Using the well-defined suspension, systematic studies of particle deposition kinetics were carried out. The coverage of the self-assembled particle monolayers was determined by AFM and SEM imaging. Particle deposition was carried out under diffusion controlled transport conditions. For long deposition times, the saturation coverage was attained, systematically increasing with ionic strength, up to 0.48 for I = 0.15M NaCl. The deposition kinetic runs were adequately interpreted using the random sequential adsorption (RSA) model. This model was also used to determine the specific density of silica particles that confirmed their porous structure. Additionally, the particle desorption kinetics was studied using AFM and SEM methods. It was confirmed that silica nanoparticle desorption was practically negligible within the time period of 60 hours. Our experimental data proved, therefore, that it is feasible to produce uniform and stable silica particle monolayers of desired coverage in the self-assembly processes, controlled by the bulk suspension concentration and the ionic strength. Such monolayers may find practical applications as substrates for selective protein and nanoparticle deposition, or various catalytic applications.

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Publication details

The article was received on 09 Jun 2017, accepted on 27 Jul 2017 and first published on 27 Jul 2017


Article type: Paper
DOI: 10.1039/C7CP03876C
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    Silica Nanoparticle Monolayers on Macroion Modified Surface: Formation Mechanism and Stability

    M. Morga, Z. Adamczyk and D. Kosior, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP03876C

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