title: Stability of silver nanoparticle monolayers determined by in situ streaming potential measurements.
abstract: A silver particle suspension obtained by a chemical reduction was used in this work. Monolayers of these particles (average size 28 nm) on mica modified by poly(allylamine hydrochloride) were produced under diffusion-controlled transport. Monolayer coverages, quantitatively determined by atomic force microscopy (AFM) and SEM, was regulated by adjusting the nanoparticle deposition time and the suspension concentration. The zeta potential of the monolayers was determined by streaming potential measurements carried out under in situ (wet) conditions. These measurements performed for various ionic strengths and pH were interpreted in terms of the three-dimensional (3D) electrokinetic model. The stability of silver monolayers was also investigated using streaming potential and the AFM methods. The decrease in the surface coverage of particles as a function of time and ionic strength varied between 10-1and 10-4M was investigated. This allowed one to determine the equilibrium adsorption constantKaand the binding energy of silver particles (energy minima depth). Energy minima depth were calculated that varied between -18 kT forI= 10-1M and -19 kT forI= 10-4for pH 5.5 andT= 298 K. Our investigations suggest that the interactions between surface and nanoparticles are controlled by the electrostatic interactions among ion pairs. It was also shown that the in situ electrokinetic measurements are in accordance with those obtained by more tediousex situAFM measurements. This confirmed the utility of the streaming potential method for direct kinetic studies of nanoparticle deposition/release processes.
authors.affiliation: Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239 Kraków, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Morga
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Adamczyk
authors.forename: Magdalena
authors.initials: M
authors.lastname: Oćwieja
keywords: Deposition of silver particles; Monolayers of silver particles; Release kinetics of silver nanoparticles; Streaming potential of silver particle monolayers