MIT Finally Develops a Surface Design that Repels Virtually Any Liquid

A team of researchers has overcome the condensation issue faced by most omniphobic surfaces to create what may be the best liquid-repelling design yet.

The scientific community, for the past decade, has been singing the praises of nanotechnology, and based on the astounding results that can be achieved when it's put to use, it's for a good reason.

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From using it in the development of methods for delivering potentially life-saving drugs inside the human body, to even employing it to recreate classic works of art, the number of applications continues to be consistently diverse.

A team of researchers at MIT are using nanotechnology to solve an old dilemma that has stumped many scientists: how to design a surface that is consistently liquid repelling in every type of condition.

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The team's work was a true collaboration, made possible by generous support from the Abu Dhabi National Oil Company, the Air Force Office of Scientific Research, the Office of Naval Research, the Masdar Institute of Science and Technology in Abu Dhabi (now under the name of Khalifa University) and the National Science Foundation, all of which formed an agreement with MIT to encourage the research. 

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Revisiting Old Research

The study involved taking a fresh approach toward omniphobic surfaces, which as the name implies, refers to a type of surface which can "reject" all types of liquids. Although this is by no means the first time that omniphobic surfaces have been considered as a viable option in achieving liquid-repelling results, the problem of condensation always remained, a frustrating challenge which the researchers described as a "phenomenon ubiquitous in both nature and industrial applications".

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To successfully produce these results, the team strictly controlled the (1) temperature and (2) scale of the materials. The surface was able to repel liquids up to 10 °C below the dew point, with results lasting over a 3-week period. In terms of the reentrant cavities, or ridges, through which the liquid would pass, a 100 nm size was chosen, which stopped the two processes of nucleating AND dispersing from occurring.

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MIT Finally Develops a Surface Design that Repels Virtually Any Liquid
A Look at the Impenetrable Surface             Source: Kyle Wilke/MIT

The process of making the ridges involved a number of steps including carving out the ridges, coating their edges, and then carving out a space within the new coatings: the result was an iron-clad surface.

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MIT Mechanical Engineering Professor Kyle Wilke describes how the team created a very delicate process in order to overcome the hurdle of condensation: "Many liquids are perfectly wetting, meaning the liquid completely spreads out. Those are very difficult to repel. The only way to do it is through very specific surface geometry, which is not that easy to make

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“We wanted a structure that one defect wouldn’t destroy," he adds.

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Will the Industry Come Knocking?

The team's research suggests that by refining the process of creating robust surface-repellant surfaces, that many in the industry will begin to reconsider the merits of omniphobic surfaces. The range of applications covers various refrigerants as well as hydrocarbons which can be used in the form of lubricants, fuels and alcohols. 

Details about the research appear in a paper, titled "Toward Condensation-Resistant Omniphobic Surfaces", which was published October 9th in the ACS Nano journal.

Via: MIT

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