Nanoparticle safety raises questions

U.S. initiative focuses on health as well as economic impacts of nanotechnology.

By Seán Ottewell, editor at large

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The engineering perspective

 

Chemical engineers, both in academia and industry, already are active in such areas.

For instance, at Washington University, St. Louis, Mo., Pratim Biswas, chair of the Department of Energy, Environmental and Chemical Engineering, has shown that he can independently control the size of the nanoparticles — keeping their properties the same. His technique, which relies on a flame aerosol reactor, also enables the materials to be made in large quantities in scalable systems, opening up prospects for new and unique uses. “The applications are plentiful,” said Biswas. “… If I can make materials of very narrow sizes, I can study the properties as a function of size, which has not been possible in the past, with very precise controls so we can do fundamental research. And that allows me to come up with new applications.”

However, Biswas was quick to point out that with all these new applications come budding new fields of study — particularly nanotoxicology. In it, nanotechnologists join forces with biologists to determine the safety of particles. For example, a particular size particle may provide the best effects in a cosmetic but manufacturers must ensure that it doesn’t cause toxic effects in a person’s body.

“We don’t want to just release it to the environment. The general feeling is that you have to be proactive, make sure everything is OK and then go, so here you are trying to be as cautious as possible,” he said.

Meanwhile, many chemical companies, of course, also are looking at nanotechnology.

BASF, Ludwigshafen, Germany, for instance, has already invested more than 180 million Euros in research to put nanotechnology to practical benefit.

The company has developed new synthesis routes for plastic foams with nanodimensional pores that prevent gas molecules from colliding and therefore reduce the material’s ability to conduct heat by more than 60%; such foams should suit applications in refrigerators, buildings and airplanes.

The firm also has developed cube-shaped nanostructures known as metal organic frameworks (MOF). Thanks to their nanodimensional pores, MOFs can store energy-rich gases such as natural gas. Because the nanocubes also store hydrogen, they could have a future use as energy sources for electronic devices.

Then there are the next-generation sources for illumination — organic light-emitting diodes (OLED). BASF scientists reckon that they require only half as much energy as conventional energy-saving light bulbs.

Some of the company’s nanotechnology developments already have reached the marketplace. For instance, the latest Audi A4 and A5 automobiles feature its Ultradur High Speed nanotechnology-based engineering plastic in their door control devices.

The material was chosen because of its low warpage, which ensures a rigid housing, while good flowability allows simple injection molding (Figure 1).

Figure 1. Low warpage of nanotechnology-based plastic provides a more rigid housing for door control devices. Source: BASF.Figure 1. Low warpage of nanotechnology-based plastic provides a more rigid housing for door control devices. Source: BASF.Figure 1. Low warpage of nanotechnology-based plastic provides a more rigid housing for door control devices. Source: BASF.

Figure 1. Low warpage of nanotechnology-based plastic provides a more rigid housing for door control devices. Source: BASF.

Similarly, the firm has just launched its first three Ultramid High Speed products. Filled with glass fiber or mineral nanoparticles, they are said to exhibit marked improvements in flow properties and much better resistance to heat aging at high temperatures (Figure 2).

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