COLL 395 |
| Fe0/Fe3O4 core/shell nanoparticles require adsorbed polyelectrolytes to form stable dispersions in water and to transport effectively in groundwater, where they are designed to serve as in situ remediation agents. Layer thickness and charge density are key determinants of the stabilizing electrosteric forces. The irregular shapes of Fe0 nanoparticles make it challenging to determine adsorbed layer thicknesses by conventional light scattering methods. The thickness and charge density of adsorbed layers of poly(styrene sulfonate), carboxymethylcellulose, and polyaspartate with a range of molecular weights were determined by applying Ohshima's soft particle theory to electrophoretic mobility data. The extent of adsorption was determined separately. Layer thicknesses ranged from 7 nm for 90 kg/mole carboxymethylcellulose to 198 nm for high molecular weight poly(styrene sulfonate). The thickness of poly(styrene sulfonate) layers increased nearly two-fold by increasing ionic strength during adsorption. Fe0 nanoparticle colloidal stability was strongly correlated with layer thickness. |
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The Physical Chemistry of Environmental Interfaces
2:00 PM-6:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 225, Oral
Division of Colloid & Surface Chemistry |