Textile Coating

Let it rain! New coatings make natural fabrics waterproof

David L. Chandler, MIT News Office1

Fabrics that resist water are essential for everything from rainwear to military tents, but conventional water-repellent coatings have been shown to persist in the environment and accumulate in our bodies, and so are likely to be phased out for safety reasons. That leaves a big gap to be filled if researchers can find safe substitutes.
Now, a team at MIT has come up with a promising solution: a coating that not only adds water-repellency to natural fabrics such as cotton and silk but is also more effective than the existing coatings. The new findings are described in the journal Advanced Functional Materials, in a paper by MIT professors Kripa Varanasi and Karen Gleason, former MIT postdoc Dan Soto, and two others.
«The challenge has been driven by the environmental regulators» because of the phase-out of the existing waterproofing chemicals, Varanasi explains. But it turns out his team’s alternative actually outperforms the conventional materials.
«Most fabrics that say ‹water-repellent› are actually water-resistant,» says Varanasi, who is an associate professor of mechanical engineering. «If you’re standing out in the rain, eventually water will get through.» Ultimately, «the goal is to be repellent — to have the drops just bounce back.» The new coating comes closer to that goal, he says.

Massachusetts Institute of Technology, Cambridge, MA 02139-4307 USA, news.mit.edu