Classical density functional theory for nanoparticle-laden droplets

Droplets of a pure fluid, such as water, in an open container surrounded by gas, are thermodynamically unstable and evaporate quickly. In a recent paper [Archer et al., J. Chem. Phys. 159, 194503 (2023)], we employed lattice density functional theory (DFT) to demonstrate that nanoparticles or solutes dissolved in a liquid droplet can make it thermodynamically stable against evaporation. In this study, we extend our model by using continuum DFT, which allows for a more accurate description of the fluid and nanoparticle density distributions within the droplet and enables us to consider size ratios between nanoparticles and solvent particles up to 10:1. While the results of the continuum DFT agree well with those of our earlier lattice DFT findings, our approach here allows us to refine our understanding of the stability and structure of nanoparticle-laden droplets. This is particularly relevant in light of the recent global COVID-19 pandemic, which has underscored the critical role of aerosol particles in virus transmission. Understanding the stability and lifetime of these virion-laden aerosols is crucial for assessing their impact on airborne disease spread.