Controlling the drying characteristics of suspensions via colloidal interactions: Particle-scale modeling

During drying of colloidal suspensions, evaporation of the suspending liquid drives the formation of concentrated particle layers beneath the receding free surface. The particle layers can lower the drying rate especially when the suspensions contain small nanoparticles. We investigate how such drying characteristics are affected by interactions between particles by use of Langevin dynamics simulations, for which we develop an analytical model to evaluate the decreasing drying rate from the permeation resistance of the formed particle layers. Considering aqueous suspensions where the particles interact through DLVO potentials, we show that there is an ionic strength where the drying rate is the most lowered and that the decrease in the drying rate is remarkably suppressed when the particles aggregate at sufficiently high ionic strength. This behavior reflects the structure of particle layers varied by the interactions. Our result provides an example how to control the drying characteristics by suspension composition. •A particle-scale model based on Langevin dynamics for predicting the drying characteristics of colloidal suspensions.•An analytical model is also derived to describe the drying rate decreasing with the structure formation of the particles.•The drying characteristics are controlled by ionic strength through the DLVO potential.•The drying rate is minimized at an ionic strength.•The temporal decrease in the drying rate is suppressed at high ionic strength where the particles aggregate.