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arXiv · 0904.2606

Forces between functionalized silica nanoparticles in solution

J. Matthew D. Lane·Ahmed E. Ismail·Michael Chandross·Christian D. Lorenz·Gary S. Grest
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Abstract

To prevent the flocculation and phase separation of nanoparticles in solution, nanoparticles are often functionalized with short chain surfactants. Here we present fully-atomistic molecular dynamics simulations which characterize how these functional coatings affect the interactions between nanoparticles and with the surrounding solvent. For 5 nm diameter silica nanoparticles coated with poly(ethylene oxide) (PEO) oligomers in water, we determined the hydrodynamic drag on two approaching nanoparticles moving through solvent and on a single nanoparticle as it approaches a planar surface. In most circumstances, acroscale fluid theory accurately predicts the drag on these nano-scale particles. Good agreement is seen with Brenner's analytical solutions for wall separations larger than the soft nanoparticle radius. For two approaching coated nanoparticles, the solvent-mediated (velocity-independent) and lubrication (velocity-dependent) forces are purely repulsive and do not exhibit force oscillations that are typical of uncoated rigid spheres.

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J. Matthew D. Lane, Ahmed E. Ismail, Michael Chandross, Christian D. Lorenz, Gary S. Grest. 2009-04-16. Forces between functionalized silica nanoparticles in solution. https://doi.org/10.1103/physreve.79.050501

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