Impact Stability of Particle Coated Droplets

The intactness and mechanical stability of liquid droplets are of utmost importance because of their applicability in various chemical and bioreactors. The powder-coated droplets (Liquid Marbles) can provide a way to increase robustness for such applications. Here, we report the deformation and stability of such liquid marbles after impacting them onto non-wetting surfaces. Not only do liquid marbles show higher robustness at lower impact velocity, but they also show exceptional stability at higher velocity impact where droplet fragmentation is unavoidable. The reason behind the robustness at lower velocities is found to be the lesser adhesion between liquid marble and surface. The lower adhesion helps in early lift-off from the surface; thus, liquid marble cannot stretch beyond the critical ratio specified by Rayleigh-plateau criteria, and fragmentation is delayed. In contrast, the higher velocity intactness was due to the early fingering instability (Liquid Flower). We found the active role of jamming and particle distribution in such early liquid flower formation, responsible for higher viscous losses and mechanical stability.