for powerplants, heating and air conditioning, and desalination. Rare earth oxides, which are found to exhibit intrinsically hydrophobic surfaces, offer an alternative to surface coatings, allowing the development of thermally stable hydrophobic surfaces for heat exchangers operating at high temperature Ultrahydrophobic desalination membranes for membrane distillation have also been fabricated for improved fouling resistance, which can be fabricated effectively with chemical vapor deposition. It has been also suggested that the superhydrophobic surfaces can also repel ice or prevent ice accumulation leading to the phenomenon of icephobicity. However, not every superhydrophobic surface is icephobic and the approach is still under development. In particular, the frost formation over the entire surface is inevitable as a result of undesired inter-droplet freezing wave propagation initiated by the sample edges. Moreover, the frost formation directly results in an increased frost adhesion, posing severe challenges for the subsequent defrosting process. By creating hierarchical surface, the interdroplet freezing wave propagation can be suppressed whereas the ice/frost removal can be promoted. The enhanced performances are mainly owing to the activation of the microscale edge effect in the hierarchical surface, which increases the energy barrier for ice bridging as well as engendering the liquid lubrication during the deicing/defrosting process. The ability of packaging to fully empty a viscous liquid is somewhat dependent on the surface energy of the inner walls of the container. The use of superhydrophobic surfaces is useful but can be further improved by using new lubricant-impregnated surfaces. See also Hydrophobe Hydrophobicity scales Superhydrophobic coating Lotus effect Contact angle meter References External links What are superhydrophobic surfaces? Contact angle measurements on superhydrophobic surfaces in practice Chemical properties Surface science Intermolecular forces Articles containing video clips