Effects of the inner droplet of double emulsions on the film drainage during a head-on collision

Abstract

As a critical stage which severely affects the final coalescence of droplets, film drainage in the collision process of two simple droplets has been deeply studied for many years. However, the collision of multiple emulsions which contain other phases (like daughter droplets or particles) has never been studied although multiple emulsions are very important in emulsion industries nowadays. In this paper, the head-on collision of two core-shell double emulsions with equal sizes is investigated through a boundary integral method to disclose the effects of the inner droplet on the film drainage. When capillary number Ca is relatively high, due to the effect of the inner droplet on the inner circulation of mother droplets, the film drainage of double emulsions includes three stages: drainage, drainage halt, and second drainage, instead of two stages for that of simple droplets: drainage and drainage halt.

The transformation dynamics towards equilibrium in non-equilibrium w/w/o double emulsions

“…8,9,17 The configuration of the innermost droplets in non-equilibrium double emulsions is also induced sometimes hydrodynamically and frozen by photo-curing the droplets into particles. 18,19 An understanding of the kinetics of the transition would enable the engineering of different particle morphologies; however, so far, most experimental efforts have focused on the relationship between the spreading coefficients and the equilibrium morphology of the double emulsion drops. The dynamics from the energetically unfavorable state to the equilibrium state, especially how the innermost droplet de-wets from the host droplet, still remain unclear.…”