DOI: 10.5176/2251-1857_M326
Authors: Jiadao Wang and Darong Chen
Abstract:
Surface topography evidently affects spreading of liquid. In this paper, the spreading of liquid perpendicular to grooves on surfaces is discussed in detail. During the spreading of liquid perpendicular to the grooves, a theoretical model of the relationship between liquid drop volume and radius of a contact circle has been established. According to the model, the advancing and receding contact angles are determined by metastable positions of the contact line, and the metastable positions are at small ranges of continuous transitional arcs of protuberances During the advancing and receding processes of a drop, the metastable positions of the contact lines are on the outside and the inside of the surface protuberances respectively, resulting in the large hysteresis of the contact angle. For hydrophobic surfaces, although air can be entrapped in the grooves, the air has no effect on the advancing contact angle. However, the trapping air under the droplet has remarkable effect on the receding contact angle. Some experiments have been conducted, and the results support the theoretical model.
Keywords:
surface topography; grooves; contact angle; hydrophilic; hydrophobic
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