Tiny science thinks big

InTech, Jun 2004 by Fussell, Ellen

Nanotechnology is growing, building for the future.

Sunscreen using nanodispersed zinc oxide, anti-wrinkle cream incorporating vitamin A inside a polymer capsule, tennis balls made with clay polymer nanocomposites to increase bounce, and stainresistant clothing-these are just some of the consumer by-products of nanotechnology. While nanotechnology is burgeoning on the consumer side, it's also making a splash with nanomaterials in automotive applications, nanoelectronics and devices, and nanobiomedical applications. And the possibilities seem endless, say the technology's proponents.

The government is putting close to $3 billion a year into nanotechnology, said Sujeet Chand, senior vice president and chief technology officer, Rockwell Automation, Milwaukee, Wis. The Institute of Soldier Nanotechnologies at the Massachusetts Institute of Technology is looking at a nanosuit for soldiers that could sense and analyze body fluids and determine what kind of medication to give a solider to monitor vital signs." On top of that, venture capital funding is around $1 billion a year in nano-start-ups," he said. "So in total you have roughly $4 billion a year going into nanotechnology research."

Nanomaterials

Nanomaterials are perhaps the most mature of applications, Chand said. Nanomaterials, when added to regular material, can improve its strength and resistance to environmental pollutants. "We're looking at using nanomaterials in a lot of our internal products," Chand said."If we can improve the properties of lubricants like grease with nanomaterial or particle additives, that would make a big difference in electric motors. It would affect parts on circuit breakers that can improve properties,"he said.

Nanomaterials include nanoparticles in composites or material such as carbon nanotubes. A nanotube is a carbon-based cylinder that conducts electricity well. "With 100 times the tensile strength of steel, thermal conductivity better than all but the purest diamond, and electrical conductivity similar to copper, but with the ability to carry much higher currents," carbon nanotubes are the latest and greatest material on the nanotechnology horizon, said a January 2003 CMP/Cientifica white paper on nanotubes.

One application includes a television with carbon nanotubes in the display instead of liquid crystal displays (LCDs) used in today's flat-screen Ws and computer monitors. A Forbes/Wolfe 2003 nanotech product guide explained how organic light emitting diodes (OLEDs) are much brighter than LCDs.They also don't require backlighting.

In another application, General Motors uses composite material for the running boards of its Astro and Safari minivans. The theory is durable composites with nanoparticles could increase fuel efficiency. General Motors is also now using a lightweight, high-performance nanocomposite material in the body of side molding of the 2004 Chevrolet Impala, GM's highest volume car, said a January 2004 GM press release. The nanocomposite application provides a 7% weight savings of the body side moldings per vehicle and improved surface quality. GM uses nearly 540,000 pounds of nanocomposite material per year-the highest volume of olefin-based nanocomposite material use in the world.

The National Science Foundation estimated nanotechnology applications may be worth more than $1 trillion in the global economy in the next ten years or a little more. The nanocomposite material used in the GM vehicles is the result of research at the GM Research & Development Center in Warren, Mich, and an exclusive GM development agreement with Bassell, a producer of polypropylene resins for plastics and southern Clay Product, Inc., a nanoclay supplier out of Gonzales, Texas.

JihuiYang of the Materials and Process lab at General Motors in Warren, Mich., explained the benefits of lower-cost carbon nanotubes in a 2003 National Science Foundation presentation. Yang said this new class of materials is made of nanocomposites whose distinguishing factors include a filler size on the molecular scale. A nanofiller equals the size of a fingernail; a talc is comparable to an 18-inch beach ball; and glass fiber is 1 mile long and 5 feet in diameter. When you add electrical conductivity to polymer composites (closures and tires for example), you see static dissipation (electrokinetic phenomena, lightning strikes, and high-voltage wires), electromagnetic compatibility (reduction in measured equation of invariance), and enhanced thermal conductivity, Yang said.

One challenge is replacing current methods in automotive applications, such as cladding and facias, with nanocomposites, Yang said. An ongoing challenge is getting high-volume use. There's a growing need to get the cost down, both for structural applications and for hybrid-electric-vehicle battery applications, Yang said in his presentation. Nanomaterials of interest to the automotive community include thermoelectrics (grown using nanotemplates and nanostructures such as clathrates and skutterudites), nanocrystalline metals for superplastic forming and high strength, nanocatalysts to reduce unwanted engine emissions and fuel-cell catalysts, and tribology and surface films.