In a Soft Matter paper, we have used molecular dynamics simulations to demonstrate that a binary solvent can be used to stratify colloidal mixtures when the suspension is quickly dried. Opposite concentration gradients can develop in a rapidly evaporating binary solvent mixture of two solvent components with the more volatile solvent depleted near the evaporation front while with the less volatile solvent enriched in the same region. The gradients can be used to stratify mixtures of colloidal particles having contrasting preferences for the different solvent components. This research suggests a facile approach of controlling colloidal stratification with mixed solvents.

In a Polymers paper, we developed a moving interface method for the simulation and modeling of the evaporation process of soft matter solutions (polymer solutions, colloidal suspensions, and their mixtures). The theoretical foundation of the method, its implementation and applications to a wide range of drying systems, and its potential limitations and pitfalls are all discussed in detail.

In a JCP paper, we compared molecular dynamics simulations of drying bidisperse nanoparticle suspensions with an explicit or implicit solvent model. Our results showed that when carefully matched, both models yield similar stratification behavior when the suspensions were dried quickly. Our work thus paved the way of using implicit solvent models of studying the drying of particle suspensions. We also pointed out the limitations of implicit solvent models and the situations where  explicit solvent simulations are required.

In a Langmuir paper, we explored an approach to control stratification in drying suspensions of polydisperse particles using thermophoresis. The approach is based on the observation that nanoparticles of different sizes have different responses to a thermal gradient. With an externally controlled thermal gradients in the drying suspensions, we demonstrated that stratification can be controlled on demand. The results may point to potential experimental strategies to tune the outcome of drying in polydisperse particle suspensions.

In a Langmuir paper, we studied the stratification in a bidisperse nanoparticle suspension induced by solvent evaporation with an explicit solvent model. For very fast evaporation, the competition between diffusiophoresis, which favors small-on-top stratification, and thermophoresis, which is induced by the evaporative cooling and favors large-on-top stratification, can lead to interesting physics.

In a JCP paper, we explored how to use a polymer brush to order nanoparticles into superstructures. Evaporation conditions of the solvent and grafting density of the brush can be combined to yield desired two-dimensional close-packed lattices of nanoparticles, which may lead to useful fabrication technology to make such superstructures.

In a ACS Macro Letters paper, we showed that evaporation rate has a strong effect on the distribution of nanoparticles in a polymer matrix and controlled evaporation can be used to tune nanoparticle dispersion in a nanocomposite. The key is to exploit the nonequilibrium nature of an evaporation process. This work is related to the recent emerging topic of stratification in a drying colloidal dispersion.