Effects of surface roughness on characteristics of liquid transfer due to breakage of liquid meniscus bridge

Abstract

We investigated experimentally the effects of surface roughness on liquid transfer due to breakage of the liquid meniscus bridge. A liquid meniscus bridge was formed between a hemispherical glass surface (radius of curvature R = 10 mm) and a glass plate. The liquids used as test sample were ethylene glycol and n-tetradecane. The contact angles at the two solid interfaces were set the same by coating the surfaces with an oil repellent to mitigate the contact angle effects. More liquid was found to be transferred to the rougher surface, despite the contact angles being nearly the same. This phenomenon cannot be explained by the theory for smooth surfaces because the theory predicts about a 50 % transfer. Furthermore, on measuring the force curve we found that the attractive meniscus force increases as surface roughness increases. We suggested that these experimental results arise from the difference in surface roughness of the two solids.