LAUSR

Abstract This is an original study on the rubbing of ruptured bubbles on a hydrophobic solid surfaces. A bubble protruding from a capillary tube attached to the objective of a microscope was pressed gently against a hydrophobic solid surface by gradually increasing the pressure inside of the capillary tube. At a certain special “gap” value the pressure inside of the capillary tube caused the formation of a wetting film, which was observed interferometrically. The film ruptured a short time after its formation, leading to the development of three-phase contact line (TPCL) on the solid surface. The TPCL rubs on the surface as the latter moves tangentially. At a certain critical speed of motion of the solid surface the bubble detaches from the surface. The value of this critical speed depends on the pressure inside the bubble, the level of the hydrophobicity and the visco-elastic modulus of the surface. We call for further investigation of this interesting phenomenon.