Electrostatic formation of liquid marbles - Influence of drop and particle size

We report the first study of the influence of drop and particle size on the electrostatic manufacture and subsequent stability of liquid marbles. It is clear from this study that the 'rules' for electrostatic formation of liquid marbles are quite different for those for conventional direct-contact manufacture. Formation of liquid marbles was observed when an earthed water drop of volume 3-7 mu L was brought into proximity with a bed of highly charged polystyrene particles of diameter 22-153 mu m. Under appropriate conditions the particles jumped to and coated the drop, producing a particle-liquid aggregate that dropped to the bed surface in the form of either a stable liquid marble or a particle-stabilised sessile drop. The subsequent evolution of the physical dimensions of the metastable aggregate was measured as the liquid drained into the bed, and its stability assessed. Formation of stable liquid marbles appeared to occur more easily for smaller drops and larger particles, and some of these considerably exceeded the conventionally-understood limit for the ratio of particle to drop size of stable liquid marbles. (C) 2016 Published by Elsevier B.V.