STOCKHOLM - A transparent wood material claimed to be suitable for mass production could replace windows and solar panels in the future, say researchers at Stockholm's KTH Royal Institute of Technology.

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 semi-transparent 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.
A research was published in BioMacromolecules Journal. Here's an excerpt:

Optically transparent wood with transmittance as high as 85 percent and haze of 71 percent was obtained using a delignified nanoporous wood template. The template was prepared by removing the light-absorbing lignin component, creating nanoporosity in the wood cell wall. Transparent wood was prepared by successful impregnation of lumen and the nanoscale cellulose fiber network in the cell wall with refractive-index-matched prepolymerized methyl methacrylate (MMA).

During the process, the hierarchical wood structure was preserved. Optical properties of TW are tunable by changing the cellulose volume fraction. The synergy between wood and PMMA was observed for mechanical properties. Lightweight and strong transparent wood is a potential candidate for lightweight low-cost, light-transmitting buildings and transparent solar cell windows.

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