As anyone looking at trees the last week or so has noticed, the leaves have taken on the red, yellow, orange and brown hues of Autumn. The cool crisp days and evenings signal that Fall has arrived. And to paraphrase Shelley, "If Fall comes, can Winter be far behind?"
And with Winter comes snow, sleet, and freezing rain. The latter of that trio is the one that, at least in the DC area, causes something that all drivers fear most, that thin coating of ice on roadways that makes driving in Winter a challenge. For pedestrians on sidewalks, it can cause slips and falls that could cause injuries.
Liangliang Cao, a graduate student in the University of Pittsburgh’s Department of Chemical and Petroleum Engineering, and colleagues recently published an article in Langmuir, "Anti-Icing Superhydrophobic Coatings" . Noting that "to date there is little experimental/theoretical work on ice formation from supercool water on superhydrophobic surfaces" – superhydrophobic coatings are thin films, designed so that their surfaces resemble those of the lotus leaf so that water droplets drip off rather than forming puddles – the article studies "the anti-icing property of superhydrophobic coatings prepared by using nanoparticle-polymer composites", using nanoparticle silica of various sizes and applying the coating to different surfaces, ranging from aluminum pie pans to a home satellite dish.
The results of the experiments indicated that the anti-icing capabilities of the composites varied according to the size of the silica nanoparticles; ice didnot form on the composites that had silica nanoparticles between 20-50 nm in length. The probability of ice forming increased proportionately for those composites with silica nanoparticles above 50 nm in length.
The study didnot include any speculation regarding using these findings to create new treatments for roads and highways, powerlines, airplanes or anything else that would be severely affected by a buildup of ice. It does call for further research that would build on this study’s findings.
Until then, drive safely this winter.