04-10 transparent wood

[Image above] Building on their research from 2016, researchers at the KTH Royal Institute of Technology added a polymer to transparent wood that allows it to store and release heat. Credit: American Chemical Society

Do you remember a time when you played hide-and-seek with your friends at a park? As the seeker slowly (or quickly) counted to 10, you may have crawled into a playground tunnel or under a nearby bush. Or, you may have chosen a nice wide tree.

Trees are an ideal hiding spot—they are easy to run behind, easy to leave when you run for home base, and, importantly, cannot be seen through.

Or should we say could not be seen through?

In March 2016, researchers at the KTH Royal Institute of Technology in Stockholm, Sweden, announced they had developed a technique that turns wood transparent. They did so by removing lignin (a complex organic structural polymer) and replacing it with acrylic (often known as Plexiglass). Although this wood was not as clear as glass, the researchers noted its potential for use as solar cells.

When lignin is removed from wood, the wood turns white. Credit: American Chemical Society, YouTube

(A study later that same year by University of Maryland researchers demonstrated the efficacy of wood windows compared to glass windows.)

Now, three years later, the KTH researchers presented their new work on transparent wood last week at the American Chemical Society (ACS) Spring 2019 National Meeting & Exposition in Orlando, Fla. Compared to their original transparent wood, which used acrylic, the KTH researchers included another polymer called polyethylene glycol (PEG) as well.

“We chose PEG because of its ability to store heat, but also because of its high affinity for wood,” says Céline Montanari, a Ph.D. student at KTH, in an ACS news release. “In Stockholm, there’s a really old ship called Vasa [sic], and the scientists used PEG to stabilize the wood. So, we knew that PEG can go really deep into the wood cells.”

Like their earlier version, the PEG wood is transparent and strong, but it has the added bonus of storing and releasing heat (because PEG is a phase-change material). In the news release, KTH biocomposites professor Lars Berglund explains that the only nonbiodegradable material in the wood is the acrylic, but “this could be replaced by another bio-based polymer.”

In the video below, watch the process of turning wood from an opaque to transparent material. If you are interested (and have time), the full 20-minute ACS presentation can be viewed here.

I guess we can no longer take it for granted that wood will be an opaque material. But though transparent wood for interior design could be available in as little as five years (according to the KTH researchers), we still can definitely take for granted that trees in the park will provide excellent, opaque hiding places.

Credit: American Chemical Society, YouTube