A slippery liquid-infused porous surface (SLIPS), liquid-impregnated surface (LIS), or multi-phase surface consists of two distinct layers. The first is a highly textured or porous substrate with features spaced sufficiently close to stably contain the second layer which is an impregnating liquid that fills in the spaces between the features. The liquid must have a surface energy well-matched to the substrate in order to form a stable film. Slippery surfaces are finding applications in commercial products, anti-fouling surfaces,

anti-icing Deicing is the process of removing snow, ice or frost from a surface. Anti-icing is the application of chemicals that not only deice but also remain on a surface and continue to delay the reformation of ice for a certain period of time, or preve ...

and biofilm-resistant medical devices. Adaptive Surface Technologies and LiquiGlide are commercial examples of liquid-impregnated surfaces, invented at

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

and the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

. SLIPS type surfaces have a number of advantages over traditional lotus based superhydrophobic surfaces. The free flowing liquid allows for the creation of a smooth surface with the ability to self-repair. This smooth surface often results in a low sliding angle for both high and low surface tension liquids. Finally, SLIPS surfaces can be made optically transparent unlike many traditional superhydrophobic surfaces that scatter light due to having structure on the same order as visible light. However, the longevity of SLIPS for prolonged

applications have been of concern. In this regard, replacing the lubricant in SLIPS with a phase switching liquid (PSL) can yield promising results. PSLs are a class of phase change materials, which are in liquid state under ambient conditions and have a

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...

higher than the freezing point of water. Thus the PSL changes into solid phase in a cold environment before water freezing can happen. While PSL impregnated textured surface behave as a traditional SLIPS in ambient conditions, when operated below the

of PSL, they resist PSL displacement out of surface texture by water, engendering enhanced

icephobicity Icephobicity (from ''ice'' and Greek φόβος ''phobos'' "fear") is the ability of a solid surface to repel ice or prevent ice formation due to a certain topographical structure of the surface.Meuler, A. J. et al. Relationships between Water Wetta ...

even on hydrophilic substrates.

References

American inventions Massachusetts Institute of Technology Surfaces {{chem-stub