Glasses that won't fog and windows that won't freeze

Glasses that won't fog and windows that won't freeze

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News & Events - Engineering News

March 8, 2013

Foggy glasses might not seem like a particularly daunting engineering challenge, but the broader problem of condensation on glass can actually cause problems everywhere from the highway to the research lab. The issue has proven pervasive enough to draw engineering resources from a variety of different industries, but one group at the Massachusetts Institute of Technology might have found a lasting solution.

The difficulty with condensation is that there are multiple factors at play when finding a solution.

Traditionally, many glass makers have chosen to create a surface that actually attracts water in such a way as to prevent it from significantly distorting visibility. However, these types of hydrophilic coatings are generally not suitable for uses where a high degree of accuracy is needed, since differences in the distribution of the water can lead to sufficient inconsistencies to spoil an image.

At the same time, hydrophilic glass can also be susceptible to frost in cases where the temperature drops below freezing.

To avoid this problem, the MIT team, led by professor of polymer materials science and engineering Michael Rubner, attempted to create a material that was hydrophilic enough to provide a layer of protection for the glass while also being hydrophobic enough to avoid the problems of condensation distortion and frost. They accomplished this with a material that attracted and readily absorbed gaseous water that would not readily freeze within the coating.

This effect is created from two common industrial polymers arranged in an innovative multi-layer coating.

"The magic of what we do is nanoscale processing," explained Rubner. "These are common polymers. They're well-known and cheap, but brought together in a unique way."

Interestingly, the biggest challenge of finding this combination of polymers was actually the lack of a standardized process for testing different glass coatings, which the team was able to develop in the course of its research. The materials would be cooled down to as low as 20 degrees Celsius and then moved to a humid environment where condensation was likely to form.

After testing several formulations, one coating developed by the researchers was able to remain entirely clear despite the high humidity.

While the biggest application of this technology would likely be automobile windshields, the growing use of wearable electronics such as the much-discussed Google Glass could make it more appealing for some types of consumer products as well.

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