Thermophoresis of Janus nanoparticles in liquids.

Abstract

In this work, we investigate the thermophoresis of Janus nanoparticles in liquids through molecular dynamics simulations. Thermophoretic forces acting on cylindrical Janus nanoparticles are calculated through MD simulations by varying the particle size, the heterogenous surface energies, and the mean temperature of the fluid. It is found that a transition from negative thermophoresis to positive thermophoresis occurs when these parameters are varied. The surface energies and mean temperature affect both the magnitude of the thermophoretic force and the transition from negative to positive thermophoresis. However, the particle size only influences the magnitude of the thermophoretic force, not the transition from negative to positive thermophoresis. Contributions of the total energy and pressure of fluid molecules are studied by evaluating the excess enthalpy density around the particle. A general scaling relationship for the thermophoretic force is developed using dimensionless numbers. This work advances the understanding of the thermophoresis of Janus nanoparticles and offers theoretical support for manipulating Janus nanoparticles in liquids by temperature gradients.