Dynamic behavior of bubbles on a porous membrane with different wettabilities

Porous structures have attracted considerable attention in handling and collecting gas bubbles underwater. However, dynamic behavior of bubbles on porous surface with different wettability is less understood so far. Here, we experimentally studied the dynamic behavior of bubbles beneath the porous membranes with different wettabilities. Especially, the bubble disappearance pattern varies distinctively depending on the wettability of the porous membrane. Such pattern was classified into three stages: water-film breakage, constant contact line, and constant contact angle. Bouncing of a bubble was preceded before adhesion of the bubble on the hydrophilic (HM) and hydrophobic membrane (HPM). Bubble removal through HM and HPM have same sequential variation in stages. Interestingly, the bubble directly bursts and spreads throughout the air film trapped by micro-nano structures of the superhydrophobic membrane. Based on the observations, the bubble behavior at each stage was examined with the aid of force balance and energy conversion. The geometric effects of the membrane on the dynamic behavior of bubbles disappearance was also discussed.