Wood windows? Swedes develop transparent wood material for buildings and solar cells

March 30, 2016
A close-up look at the transparent wood created at KTH Royal Institute of Technology. Credit: KTH Royal Institute of Technology

Windows and solar panels in the future could be made from one of the best—and cheapest—construction materials known: wood. Researchers at Stockholm's KTH Royal Institute of Technology have developed a new transparent wood material that's suitable for mass production.

Lars Berglund, a professor at Wallenberg Wood Science Center at KTH, says that while optically transparent wood has been developed for microscopic samples in the study of wood anatomy, the KTH project introduces a way to use the material on a large scale. The finding was published in the American Chemical Society journal, Biomacromolecules.

"Transparent wood is a good material for solar cells, since it's a low-cost, readily available and renewable resource," Berglund says. "This becomes particularly important in covering large surfaces with solar cells."

Berglund says transparent wood panels can also be used for windows, and semitransparent facades, when the idea is to let light in but maintain privacy.

The optically transparent wood is a type of wood veneer in which the lignin, a component of the cell walls, is removed chemically.

"When the lignin is removed, the wood becomes beautifully white. But because wood isn't not naturally transparent, we achieve that effect with some nanoscale tailoring," he says.

The white porous veneer substrate is impregnated with a transparent polymer and the optical properties of the two are then matched, he says. 

"No one has previously considered the possibility of creating larger transparent structures for use as and in buildings," he says

Among the work to be done next is enhancing the transparency of the material and scaling up the manufacturing process, Berglund says.

"We also intend to work further with different types of ," he adds.

"Wood is by far the most used bio-based material in buildings. It's attractive that the material comes from renewable sources. It also offers excellent mechanical properties, including strength, toughness, low density and low thermal conductivity."

Explore further: Swedish scientists use wood to create biodegradable, renewable alternative to Styrofoam

More information: Yuanyuan Li et al. Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance, Biomacromolecules (2016). DOI: 10.1021/acs.biomac.6b00145

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11 comments

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antialias_physorg
5 / 5 (4) Mar 30, 2016
Transparent aluminium...OK.
But transparent wood? Now things are getting silly.
(Seriously, though: this is five kinds of awesome)
Nik_2213
4.8 / 5 (4) Mar 30, 2016
Be even better if they'd used a wood-derived polymer...
hemitite
5 / 5 (2) Mar 30, 2016
If one could figure out a way to cross link cellulose chains, perhaps the plastic part would no longer be necessary for the material's transparency.
antialias_physorg
5 / 5 (4) Mar 30, 2016
The plastic isn't there for stability. It's there to generate the effect like when you use clear tape to see through frosted glass.
(google for "transparent tape frosted glass")
antigoracle
not rated yet Mar 30, 2016
-- Hey..hey...come see. I impregnated wood with chemicals and polymer to create ...taa.. daa... transparent wood!
-- That's brilliant Lars, but all of that to strip away the aesthetic qualities of the wood and produce a piece of old plastic?
Da Schneib
4.3 / 5 (3) Mar 31, 2016
It's very interesting, but I have to point out that sand is pretty common. It's not like there's going to be peak sand anytime soon.

The technology involved in making transparent wood panels is more interesting than the material itself.

Maybe they've got more trees in Sweden than sand...?
Captain Stumpy
5 / 5 (1) Mar 31, 2016
Maybe they've got more trees in Sweden than sand...?


just as long as those b-tards don't sell this to Ikea...!!!!
Nik_2213
5 / 5 (2) Mar 31, 2016
Problem with sand is it is *very* energy intensive to turn into glass. Hence the emphasis on recycling the stuff. There's a lot more chemistry involved than just shovelling pure silica beach-sand into a furnace. Also, getting bubbles out of the melt is non-trivial, slowing the process. Worse, contamination from microscopic 'inclusions' can lead to hi-rise buildings needing all their glazing replaced ASAP due to premature ageing & shattering...

FWIW, if there was an *easy* way to make glass from sand in-situ, it would be handy to stabilise sand dunes, both on low coasts and on desert margins...
Eikka
not rated yet Apr 02, 2016
The white porous veneer substrate is impregnated with a transparent polymer and the optical properties of the two are then matched, he says.


So it's basically wood impregnated in some sort of (epoxy?) resin.

So basically the same thing as clear acrylics or any other plastic, just with a filler made out of cellulose.

Incidentally, you could do the same to pure silica sand to turn it transparent. The mechanism is the same: immerse sand grains into a resin that has similiar index of refraction, and the whole thing turns transparent.
compose
Apr 02, 2016
This comment has been removed by a moderator.
Eikka
not rated yet Apr 02, 2016
This study did use delignified balsa wood (Ochroma pyramidale) with initial density of 160 kg/m3, which essentially means, 80% volume (or more) of resulting material was formed by acrylics - so I don't see big deal here.


Well, maybe it's less prone to shattering or cracking, being a composite.

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