Liquid that turns into armor is undergoing Army tests

"BALTIMORE — Army scientists are working on a liquid body armor for clothing that stays flexible during normal use but can harden to stop a projectile when hit suddenly.

Researchers hope the liquid could be used in sleeves and pants, areas not protected by ballistic vests because they must stay flexible.
The liquid, hard particles suspended in a fluid, is soaked into layers of Kevlar, which holds it in place. Scientists recently had an archer shoot arrows at it to see how well the liquid boosted the strength of a Kevlar vest. "
Seattle Times