Wettability and Morphology of Nanoparticles Influencing the Wrapping Behavior of Carrying Nanobubbles.

Nanobubbles as carriers have been recognized for their significant potential in applications such as drug delivery, flotation separation, and pollutant cleaning. However, a comprehensive understanding of the interfacial coupling dynamics between nanobubbles and the nano-objects they carry remains limited, which restricts the optimization and practical implementation of related technologies. In this work, molecular dynamics (MD) simulations are employed to systematically investigate the interactions between nanobubbles and nanoparticles with diverse physical morphologies and chemical properties. In quasi-two-dimensional systems, for circular nanoparticles of any size, an increase in MD parameter ε (i.e., particle wettability) from 0.3 to 0.8 results in the coverage fraction increasing from nearly 0% to approximately 95%. At a constant wettability, the reduction in nanoparticle size induces a relatively slight increase in the coverage fraction, typically ranging between 5% and 10%. There are three characteristic wrapping states observed for square nanoparticles, namely, fully wrapped, semiwrapped, and unwrapped. Triangular nanoparticles, on the other hand, demonstrated fully wrapped, unwrapped, and metastable states encompassing both statuses. Furthermore, the positions of the three-phase contact lines for rectangular nanoparticles and nanobubbles are determined by the length of the shorter sides. These wrapping states observed for square, triangular, and rectangular nanoparticles can be attributed to pinning of the contact line at sharp edges or corners. These findings are anticipated to offer "form-function" matching strategies for the precise design of drug delivery systems, enhancement of flotation efficiency, and improvement of contaminant cleaning processes.