The science of materials that build themselves

Years before nanotechnology became the buzzword at research institutions across the country, researchers at Pacific Northwest National Laboratory were studying how molecules arrange themselves to form materials on the nanoscale.

"This Laboratory started one of the first nanoscience projects within the Department of Energy complex about three years ago," said Jun Liu, a senior staff scientist in materials chemistry and research. "A small group of people in materials science, including Gregory Exharos, Pacific Northwest's Basic Energy Sciences materials program manager, have been pushing toward this for some time."

Pacific Northwest's research is focused on self-assembly—a new approach that allows materials to build themselves rather than forcing molecules into certain structures one by one. DOE's Office of Basic Energy Sciences is funding this fundamental science project to build a better understanding of how different combinations of molecules will arrange themselves into different structures, how these structures affect material properties and how to adopt this approach to build new materials.

Liu explained that organic and inorganic molecules, even a simple combination of soap and water, have a tendency to organize themselves into nanostructures. For example, depending on the proportion of soap, water and oil or salt in the mix, molecules will form nanostructures in the shape of spheres, rods or honeycombs.

The conventional method used to build specialized materials involves making a ceramic powder under high pressure and often involves high-temperature treatment. Self-assembly, on the other hand, can take place at room temperature. Materials created through self-assembly also could offer improved physical, chemical and biological properties for a broad spectrum of applications.

"We can build materials that can be used for some interesting things," Liu said. "For example, the tiny holes in a honeycomb-like structure could be used as a nanofactory to build something else. This could be a way to isolate and control chemical reactions or to store and stabilize materials such as proteins that typically don't last long in air."

This fundamental research on how molecules behave and interact also has been the driving force behind many specific projects at Pacific Northwest for other clients. Scientists are researching potential applications including microelectronics and catalysis.

Another potential application could be drug delivery. Pharmaceuticals would be stored within the large surface area of the nanostructure and then released slowly, for example when a person's body temperature reached a certain level. When the body temperature returns to normal, the drug delivery would automatically stop. This drug delivery technology is based on a new class of "smart" nanoscale materials developed at Pacific Northwest. These "smart" materials can respond and regulate their functions depending on the surrounding environment, similar to the way biological tissues function.