Dispersion and rheology of surfactant-mediated silver nanoparticle suspensions

• Published in: Applied surface science 2010-11, Vol.257 (2), p.650-655
• Main Authors: Chen, Chun-Nan, Huang, Chih-Ta, Tseng, Wenjea J., Wei, Ming-Hsiung
• Format: Article
• Language: English
• Subjects: Acetates; Adsorption; Clusters, nanoparticles, and nanocrystalline materials; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Dispersion; Exact sciences and technology; Heterogeneous liquids: suspensions, dispersions, emulsions, pastes, slurries, foams, block copolymers, etc; Infrared and Raman spectra; Infrared and raman spectra and scattering; Material form; Nanocomposites; Nanomaterials; Nanoparticle; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanostructure; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Rheology; Silver; Solvents; Structure of solids and liquids; crystallography; Surface chemistry; Surfactant; Surfactants
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2010.07.057

Polycrystalline silver (Ag) nanoparticles were dispersed in solvent mixtures consisting of 2-butoxyethyl acetate (BCA) and diethylene glycol monoethyl ether acetate (CA) in a BCA:CA weight ratio of 5:1. Three commercially available polymeric surfactants were used, and the gravitational sedimentation, agglomerate-size distribution, isothermal adsorption, and rheological behavior of the nanoparticle suspensions were examined. One of the surfactants (hereafter termed 9250) was found effective in stabilizing the Ag nanoparticle suspensions. Both the adsorption isotherm and the Fourier transform infrared spectroscopy revealed the preferential adsorption of the 9250 surfactant molecules on the nanoparticle surface, forming a Langmuir-type monolayer adsorption in the given solvents so that a steric stabilization was rendered. An optimal surfactant concentration of 5wt.% (in terms of the solids weight) was determined experimentally. In addition, the Ag suspensions with a broad range of solids concentration (ϕ=1–16vol.%) showed a shear-thinning flow character over a shear-rate range from 1 to 4000s−1, revealing that an attractive interparticle interaction was operative. Relative viscosity (ηr) of the nanoparticle suspensions deviated from the linearity when ϕ was greater than ∼10 vol.%; at which, the attractive potential began to dominate the interparticle interactions. This ηr–ϕ dependence was compared with various existing models and the (viscosity) predictive capability of the models was discussed.