Role of hydrophobicity on interfacial fluid flow: theory and some applications.

The fluid flow through a seal interface depends on the percolating non-contact channels morphology, size and length, and on the interfacial surface energies. In particular, hydrophobic interfaces may expel fluids and decrease the fluid flow of seals, while increasing the sliding friction. We present results of interfacial fluid flow experiments on a hydrostatic column device which demonstrate how interfacial hydrophobicity can block fluid flow at interfaces and reduce the leak rate of seals. The presented results may help to understand the role of interfacial hydrophobicity in many practical applications, some of which we discuss briefly in this paper, e.g., rubber wiper blades on hydrophobic (usually wax-coated) glass, the locomotion of insects on surfaces in water, and syringes.