Solvation forces between colloidal nanoparticles: directed alignment.

We study the solvation forces between colloidal nanoparticles in Lennard-Jones liquids using molecular-dynamics simulations. We find that due to the interplay between solvent ordering and surface structure, the solvation forces between two nanoparticles can vary between attraction and repulsion as the particles are rotated relative to one another at a fixed separation. These solvent-mediated forces tend to align the nanoparticles so that they rotate to approach one another in a solution via preferred pathways. This directed alignment could play a role in the assembly of macromolecules and nanoparticles in solution.