Materials for a Small Planet
A number of NSF-supported investigators are looking for more environmentally benign substitutes for chemically synthesized materials currently in use. Dragline silk from the orb-weaving spider Nephila clavipes is one of the most promising new biomolecular materials, thanks to the silk's great strength and flexibilitygreater even than the lightweight fiber used to reinforce bulletproof helmets. Also attractive is the environmentally friendly process used to make the silk, which the spider spins from a water-based solution. Intrigued by this spider, which actually makes seven different types of silk, Lynn Jelinski, then at Cornell University and currently chemistry professor and Vice Chancellor for Research and Graduate Studies at Louisiana State University, had a vision that high-performance, renewable, silk-like polymers eventually can be made using the tools of biotechnology. She thinks scientists may be able to synthesize the key spider genes and insert them in plants, which then would express the protein polymers. The resultant materials might be used in products ranging from reinforced tennis rackets to automobile tires.
Discoveries of new materials lead to new questions, the answers to which create opportunities to find still more new materials. An example of this cycle is the work of Donald R. Paul of the University of Texas at Austin, an authority on the ways in which polymers interact when blended. Polymer blends are a powerful way of enhancing toughness or otherwise tailoring the performance of a given material. The information generated by Paul's research may lead to the development of high-performance polymeric alloys that could be used to replace metal components in automobiles. These lightweight and easy-to-fabricate alloys could help create vehicles that have greater fuel efficiency and produce fewer emissions.
At the same time, materials synthesis research is being used to investigate new metal alloys. To create these alloys, researchers must learn about the chemistry of the alloy, the microstructure basic to the alloy, and its macroscopic behavior. NSF-funded researchers, including those at the University of Alabama at Birmingham, are investigating how to control the alloy composition. Some of the alloys are thin films that will find their way into the electrical industry. Others may be used in newly designed vehicles. These alloys are not only stronger and lighter than their predecessors, but also more resistant to stress and fatigue, producing a more fuel-efficient, longer-lasting vehicle.
In research supported jointly by NSF and the U.S. Environmental Protection Agency, an environmentally benign method of polymer synthesis was discovered using liquid carbon dioxide in place of toxic volatile organic solvents. The work by Joseph DeSimone, professor of chemistry at the University of North Carolina-Chapel Hill and chemical engineering at North Carolina State University, and his graduate students received one of Discover magazine's 1995 Awards for Technological Innovation. The discovery led DeSimone and his colleagues to patent an environmentally friendly process for dry cleaning clothes that uses carbon dioxide instead of perchloroethylene, a highly toxic organic solvent in wide use throughout the industry. As the lead principal investigator for the NSF-supported Science and Technology Center for Environmentally Responsible Solvents and Processes, DeSimone continues to advance research into environmentally safe solvents. Meanwhile, other work in polymers focuses on finding ways to use plastics in place of silicon as the base material of microcircuits.
"Materials research is pushing the edge of the technologies of
a whole array of societal systems," said NSF Deputy Director
in an interview for NSF's publication, Frontiers. "It's a
very powerful catalyst for innovation. As new materials become
available and processable, they will make possible improvements
in the quality of life. And that's the heart of the leadership
issue and the competitiveness issue, isn't it? That's the future."