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Nanotech Surfaces; In Coatings and Surface Enhancements, A Little Nanotechnology Goes A Long Way
Design News, Nov. 21, 2005
By: Joseph Ogando
Engineers with problems to solve right now might not give a second thoughtto nanotechnology since so much of it still seems more like science fiction than fact. But nanotech has, in fact, already boosted the performance of commonly used materials and it promises to do even more in the near future.
While a handful of adhesives and thermoplastic compounds already contain nanoscale additives to boost bulk mechanical properties such as tensile or impact strength, nanotech’s has made a stronger impact on coatings and surface enhancements for metal, plastic, and ceramic substrates.
The reason why comes partly down to economics. Nanoscale additives don’t come cheap; even some commercial ones cost hundreds dollars per pound. So putting them in a coating and concentrating them on the surface of a part makes a lot of sense. “It’s where you get the most bang for your buck,” says Bob Kumpf, head of future business for Bayer MaterialScience LLC. And putting a tiny amount of nanoparticles in a coating can have a tremendous impact on important surface properties, such as resistance to wear, chemicals, and dirt. Nanotech coatings can influence thermal, optical, and electrical properties too. “The surface of a part is really where a lot of things happen,” says Kumpf.
Nanotechnology may also have a unique ability to balance all this added functionality with aesthetic requirements. “Nanotech is, by definition, invisible to the human eye,” says Kumpf. And invisibility means nanotech can often work its functional magic without changing the way surfaces look. Consider the case of titanium dioxide. “It’s well known for its UV resistance. But when you put it in paint, everything turns white,” says Bob Matheson, a technical manager for strategic technologies at DuPont Performance Coatings. So the company has been using nanoscale titanium dioxide particles that still offer the UV protection while remaining invisible in colored paint formulations.
Despite all the buzz it gets today, remember that nanotechnology really amounts to business as usual for the kinds of companies that develop materials, paints, and coatings. “We’re very good at dispersing nano particles, which can be tricky to handle,” says Matheson. As an example, he cites the paint industry ‘s use of carbon black and silica. “Both are true nanoparticles, and we’ve used them for thirty years.” Or to take another example, BASF has for decades offered products that incorporated nano-sized dispersions of one polymer within another.
“We’re already experts in this,” says Volker Warzelhan, senior vice president for polymer research.
Still, the really exciting work in nanotech coatings has really just begun as materials scientists intentionally take advantage of the properties that emerge when things get very small. Sally Ramsey, chief chemist and cofounder of Ecology Coatings, notes that her nanotech coatings sometimes make use of additives that have been used for years in larger, micron sizes. “What’s happening now is that we’re using nanoparticles to produce properties that wouldn’t exist with larger particles,” she explains.
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