Dual-Scale Pattern Formation in Nanoparticle Assemblies

A pseudo-3D lattice gas-based Monte Carlo simulation is used to reproduce dual-scale non-equilibrium structures formed from drying colloidal nanoparticle solutions. Morphologies possessing multiple length scale features are recreated by coupling the chemical potential to the solvent density, modelling a film thickness-dependent disjoining pressure. By assigning a sigmoidal form to the chemical potential, a switch in the dewetting mechanism at a threshold solvent density is capable of producing nanoparticle patterning at two length scales. Dual-scale cellular networks, and nanoparticle ring and fingering structures coexisting with small scale patterning, can all be generated in this way with suitable simulation parameters. Extensive exploration of the model’s parameter space maps the temperature-dependent spinodal line, and demonstrates the influence of nanoparticle concentration on morphology. The paper is published as: J. Chem. Phys. C 112, 15195-15203 (2008) and can be obtained at http://dx.doi.org/10.1021/jp803399d. ∗ Corresponding Author †Electronic address: [email protected] ‡Electronic address: [email protected]; URL: http://www.uwethiele.de