Tiny Layered Materials Make Ultra-Light Bulletproof Armor

The key is alternating layers made from materials with different abilities.

Bulletproof

This is an electron-microscope image of a cross-section of a layered polymer designed to withstand a speeding bullet. The crater was caused by an impacting glass bead, and the previously even, parallel lines of the layered structure are deformed as a result of the impact. In this test, the layered material was edge-on to the impact. Comparative tests showed that when the projectile hit head-on, the material was able to resist the impact more effectively.Thomas Lab, Rice University

Making better body armor doesn't have to be about adding bulk--it's about smart layering. A new composite material, made of tiny alternating layers a few nanometers thick, is lighter than other impact-resistant shielding material--and the process the materials scientists developed to study it could lead to even better versions in the future.

Researchers at MIT and in France developed a new self-assembling polymer material with a structure like a layer cake. Resilient rubber layers alternate with rigid glass layers to provide durability and strength. To test its mettle, the team developed a way to shoot tiny microballs at the structure to see how it held up. When shot edge-on, like in the image above, the material warped and caved at the point of impact. When shot head-on, it was 30 percent more effective at blocking the speeding ball. The microballs were hundreds of times larger than the nano-layers in the armor, so they were a realistic simulation of a bullet impact.

Nanostructures can be more effective than more familiar bulletproof materials like Kevlar because of how they behave. Things work differently at the smallest scales, and particles take on strange properties. Researchers in the United Kingdom are studying shear-thickening liquids, for instance, which are rigid nanoparticles suspended in a liquid that hardens on impact. In this latest case, a unique arrangement of materials lends added durability and strength.

But the real breakthrough here is in the way the team was able to measure these impacts. Viewed from an electron microscope, you can see tiny effects and changes in each layer of material. Further study of these distortions, like how deeply they penetrate and how far they spread, could lead to systematic improvements. This is a new and more effective way to study structured polymers, according to MIT News. Their ultimate goal is to watch the whole thing stretch and deform in real time in response to an impact.

The work appears in Nature Communications.