“What’s bouncy, bulletproof, cools you in the summer, keeps you toasty warm in winter and might help save our planet?
The answer literally grows on (and in) trees: wood—at least in the many unfamiliar guises it takes on in the lab of materials science and engineering Professor Liangbing “Bing” Hu, director of the Center for Materials Innovation at UMD. Hu is an expert in nanomaterials, which generally are manufactured to have special characteristics—like ultrastrength or superconductivity—based on their microscopic structure.
Hu got excited several years ago when he realized there was an almost infinite supply of natural nanomaterial that’s both versatile and strong, and buried in the grain structure of wood. Since then, he’s been developing different methods to access and exploit that hidden resource while developing surprising new applications that a UMD spinoff company, InventWood, is readying for market.
“Sustainability and environmental protection convinced me more and more to pursue this,” he says. “Wood is an abundant and renewable material, and an old material people have gained a lot of knowledge about through history. But in terms of innovation, this is not a crowded field.”
Read on for a few of the new ways Hu is building on a trusty standby.
Wood like you’ve never seen it—or in this case, seen through it. Hu and his lab members created nearly transparent wood by replacing its lignin with clear epoxy. The result is a beautiful building material that retains its wood grain and admits light like frosted glass, but insulates better. And in his lab’s latest discovery, published last month in Science Advances, the power of the sun helps modify the lignin, reducing the chemicals needed to create wood windows.
Stronger than steel at one-sixth the weight, wood turns literally bulletproof when Hu and collaborators remove lignin, a natural “glue” that holds the cells together. They compress what remains under extreme pressure to create a rust-free structural material that could be deployed, with support from a $4 million grant from the Department of Energy, in everything from bridges to boats.
A process of heating, freezing and chemical modification turns wood’s normally rigid structure to jelly so it rebounds like a superball. Hu had no specific goal for this recently announced discovery—other than squishiness—but now some companies are interested in exploring its use as a shock absorber.
Wood from Hu’s lab turns seawater to drinking water. Specially processed basswood, blackened by burning, floats inside a solar evaporator, sucking up saltwater through a vascular structure naturally designed to avoid clogging from impurities like salt. Under concentrated solar heat, the wood emits steam that condenses into freshwater.
Hu’s radiative cooling wood is pure white in the visual light spectrum, meaning that on building roofs, it doesn’t soak up the sun. Paradoxically, it’s pure black—but only in the invisible infrared spectrum—helping heat radiate back into outer space. The result is a several-degree difference between inside and out, even before switching on the AC.”