(192b) Study of Interfacial Modulus and Sliding Drop Motion By Centrifugal Adhesion Balance (CAB)

Akash K. Jena¹, Sirui Tang¹, Semih Gulec¹, Sakshi Yadav¹, Rafael Tadmor^*1

*Corresponding Author.

1. Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont TX 77710

We use a Centrifugal Adhesion Balance (CAB) to study the characteristics of the motion of a liquid drop across varied surfaces. These surfaces differ based on the parameter of hydrophobicity. We conducted experiments with increasing centrifugal force to determine trends for parameters, such as positions and contact angle. Along from these experiments, another objective trend is determined: interfacial modulus, G_s, which is associated with the resistance of the outermost layer of the solid surface to conform to the liquid. The drop initially pins to the surface, but with increasing lateral force, the drop depins and slides off the surface. The lateral force, which is required for this depinning, or onset of motion, is lower when the surface is more hydrophobic. Hence, surface’s hydrophobicity affects the drop’s characteristic. In addition, weak adhesion, in which the drop slides immediately, is also observed in different surfaces.