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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
to 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
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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