Forces between functionalized silica nanoparticles in solution
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, macroscale fluid theory accurately predicts the drag on these nanoscale 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.
- Publication:
-
Physical Review E
- Pub Date:
- May 2009
- DOI:
- 10.1103/PhysRevE.79.050501
- arXiv:
- arXiv:0904.2606
- Bibcode:
- 2009PhRvE..79e0501L
- Keywords:
-
- 62.25.-g;
- 81.07.-b;
- 83.80.Hj;
- 83.80.Qr;
- Mechanical properties of nanoscale systems;
- Nanoscale materials and structures: fabrication and characterization;
- Suspensions dispersions pastes slurries colloids;
- Surfactant and micellar systems associated polymers;
- Condensed Matter - Mesoscale and Nanoscale Physics;
- Condensed Matter - Soft Condensed Matter
- E-Print:
- 4 pages, 3 figs