Nanofoams Can Take a Hit

Imagine a world in which a sudden impact from an explosion or collision would do no damage to a person’s body or a building. That’s the kind of protection that scientists from the University of California nanofoamSan Diego (UC San Diego) are developing. The material? Nanofoams.

“We are developing nanofoams that help disperse the force of an impact over a wider area,” says Yu Qiao, professor of structural engineering at the Jacobs School of Engineering at UC San Diego. “They will appear to be less rigid but will actually be more resistant than ordinary foams.”

The research is in its first year of a three-year program funded by the Army Research Office. Naturally, the military is interested in how the foams could protect soldiers from blast-related injuries. But the materials also could be used to make better body armor for police officers, prevent brain injuries for any one, or prevent damage to buildings from an impact or explosion, according to a university news release.

Over the next two years, the research team wants to test the foam on metallic and polymeric nanomaterials. Often, traditional polymers can be reinforced by nanoparticles, a combination that produces novel materials that are lightweight and can be substituted for metals. These enhanced materials reduce an end-product’s weight and increase its stability.

Currently, the foams are made of a honeycomb structure in which 50% to 80% of the structure has pores that store energy from impacts. The goal is to find out the optimum pore size. Samples from pore sizes range from 10 nanometers (10 billionths of a meter) to 10 microns (10 millionths of a meter).

Preliminary tests show that samples with pores in the tens-of-nanometers range seem to perform best. Those samples can absorb energy from a blast over a wider area than samples with different pore sizes.

Testing occurs at the Jacobs School. The news release explains how the testing is done:

Samples are placed in a testing rig powered by a gas gun and subjected to increasingly stronger impacts. Researchers then put the samples under a scanning electron microscope to examine the damage. They use extensive data analysis to determine how much energy the nanofoams absorbed during the impact tests.

The material is made by the blending of two materials at a molecular level. Then the researchers use acid etching or combustion to remove one of the two materials. What is left are the pores, or nano-scale empty channels.

“People have been looking at preventing damage from impacts for more than a hundred years,” says Qiao. “I hope this concept can provide a new solution.”

Source: “Engineers Develop Nanofoams for Better Body Armor, Layers of Protection for Buildings,” UC San Diego, 3/25/13
Image by Jacobs School of Engineering at UC San Diego, used with permission.