Wood, an inexpensive and renewable resource, has many applications. Including building materials for high rises, bicycles, and foam insulation. Recently researchers developed transparent wood for potential use in windows, and solar cells, providing a cheaper alternative to silica-based glass. Led by Prof. Lars Berglund at Sweden’s KTH Royal Institute of Technology, researchers chemically remove lignin from natural wood fibers – lignin is one component of wood cell walls. What was left was a material that was “beautifully white,” but still not transparent.
In order to achieve that transparency, the material was mixed with prepolymerized methyl methacrylate (PMMA). This altered the refractive index of the resulting mixture, turning it transparent. Depending on the intended application, the finished product can also be made more translucent, by fine-tuning the wood-to-PMMA ratio.
This actually isn’t the first time we’ve seen wood turned into a transparent material, asnanofibrillated cellulose has been used to create items such as the substrate for wood-based computer chips. According to KTH, however, the new process should be particularly well-suited to large-scale applications and mass production.
The researchers are now looking at increasing the material’s transparency, scaling up the manufacturing process, and using a wider variety of woods.
“It’s attractive that the material comes from renewable sources,” says Berglund. “It also offers excellent mechanical properties, including strength, toughness, low density and low thermal conductivity.”
A paper on the research was recently published in the journal Biomacromolecules.