Surface Charge Deposition by Moving Drops Reduces Contact Angles
Xiaomei Li, Aaron D. Ratschow, Steffen Hardt, Hans‐Jürgen Butt
Abstract
Slide electrification---the spontaneous charge separation by sliding aqueous drops---can lead to an electrostatic potential in the order of 1 kV and change drop motion substantially. To find out how slide electrification influences the contact angles of moving drops, we analyzed the dynamic contact angles of aqueous drops sliding down tilted plates with insulated surfaces, grounded surfaces, and while grounding the drop. The observed decrease in dynamic contact angles at different salt concentrations is attributed to two effects: An electrocapillary reduction of contact angles caused by drop charging and a change in the free surface energy of the solid due to surface charging.
Topics & Concepts
Contact electrificationDrop (telecommunication)Contact angleMaterials scienceAqueous solutionSolid surfaceSurface chargeOpticsMechanicsComposite materialChemical physicsTriboelectric effectChemistryPhysicsElectrical engineeringEngineeringPhysical chemistryElectrowetting and Microfluidic TechnologiesElectrohydrodynamics and Fluid DynamicsSurface Modification and Superhydrophobicity