Why and how liquids wet solids or other liquids?
“Why and how liquids wet solids or other liquids?” is the title of the lecture that will be given by Manuel G. Velarde (Instituto Pluridisciplinar, Universidad Complutense de Madrid, Spain), next September 21th, at 3:00 p.m., in the Room 2.11 (Bld. 2 – FCT – Campus Gambelas UAlg). The lecture will be given in a simple approach, so it may interest to biologists and chemists, besides physicists and mathematicians.
When a droplet falls on a solid plane surface, the surface may either NOT be wetted or the droplet can spread, wetting the surface, partially or totally, the result being defined by the value of the contact angle at thermodynamic equilibrium. With the introduction of surface forces, this angle is calculated as a function of Derjaguin (isothermal) pressure via the minimization
of the appropriate excess Gibbs free energy.
Also, Young’s equation for the contact angle is reviewed and its limitations are pointed out. A possible histeresis effect due to the influence of Derjaguin’s pressure is discussed.
