Revolutionizing the future of materials

It's not exactly new, but it's certainly fascinating and promising, especially as we continue to study it. We've known about translucent wood for a few decades and talked to you about it here on occasion, but its study has seen major advances over recent years to open up interesting applications beyond construction. There are those who are already thinking about creating windows, screens, the energy sector, or even seemingly unrelated industries such as the automobile industry.

In the end… who said that the material of the future cannot be a material that man has known and dealt with for thousands and thousands of years?

Transparent wood? It may seem counterintuitive and extravagant, but transparent wood is a concept that scientists have been grappling with for a few decades. More specifically about 30 years ago Siegfried FinkThe German botanist was able to remove pigments from plant cells to study the structure of woody plants more precisely.

The article he published in the early nineties about his technology was for quite some time the reference and spearhead of the subject, but as he mentioned a few days ago article to Knowledge Magazinemagazine Annual reviewsHis study has seen remarkable developments over the past few decades, especially since Lars Berlund, from the KTH Royal Institute of Technology in Sweden, decided to move the discovery into his own field: materials science.

The key, its structure. Lars Berlund and his team at KTH are not the only ones interested in transparent wood. Its enormous potential has attracted the interest of researchers at the University of Maryland private sector. The key to their work is the structure of the wood: to give it a transparent or translucent appearance, they remove the lignin – the “glue” from the logs that gives them their color – and then fill the empty pores with a substance that ensures resistance and allows light to pass through.

What are the materials? Over the years, scientists have tried different options, specifically advancing one of the material's main lines of action. For example, the KTH team started out using polymers of fossil origin, but ended up switching to a more environmentally friendly alternative, limonene acrylate. “It is made from renewable citrus fruits, such as peel waste that can be recycled from the orange juice industry,” researcher Céline Montanari explained after its publication. Your studies In “Advanced Sciences” in 2021.

Resistant, sustainable…and transparent. That scientists and companies are exploring ways to develop transparent wood is explained by the wide range of possibilities, just as in transparent wood Featured in 2019 Horizon magazine published by the European Commission (EC). Unlike stone or concrete, wood is a renewable resource, which can help the construction industry reduce carbon dioxide emissions, and also provides a strong material.

“This wood is more weather resistant, more fire resistant, three to five times stronger and more transparent.” Timothy Poitoust explainedfrom the Woodoo company, which worked on ways to give new properties to wood.

“The results are amazing, a piece of wood can be as resistant as glass.” He explains Materials scientist Liangping Hu of the University of Maryland told Knowable Magazine. Just a few months ago he signed A.J condition Together with other researchers they highlighted the potential of transparent wood. With the addition of resin, they claim the laminate can be three times more pressure-resistant than plexiglass and ten times more resistant than glass.

from KTH confirmed In 2021, his new composite, made of wood and limonene acrylate, demonstrated “high-strength mechanical performance,” with a strength of 174 MPa and elasticity of 17 GPa. Its solution also made it possible to dispense with polymers of fossil origin, which is one of its main goals.

In search of transparency. During wood processing, scientists remove the lignin, but this does not mean that the resulting material is transparent. To achieve this, they have to fill the gaps with compounds, such as epoxy, that match Its refractive index. The sheets they deal with are usually very thin, between one millimeter and one centimeter thick. However, the thicker the wood, the blurrier the vision becomes.

Hu and Berglund's tests actually show that when working with millimeter structures, 80 to 90% of the light passes through, but Light transmittance It decreases when thickness increases. Solution with citrus derivatives provided by KTH, According to the creators' calculationsWith an optical transmittance of 90%, a thickness of 1.2 mm, and a low turbidity of 30%. Other tests He showed that wood can become lighter because it stores more heat.

Clear wood windows may be more frosted than traditional stained glass windows, but they offer other advantages, such as their resistance and insulating ability, and this same nature will make them an interesting choice for spaces where frosted glass is traditionally used.

From theory to practice. If its qualities are interesting, it is because of the range of practical applications that clear wood offers, uses that go beyond simply finding materials to make it. More sustainable construction. That responsible point Possibilities In nanotechnology, design Smart windowsOr heat storage, lighting or laser technology.

“We looked at where the light goes and what happens when it hits cellulose –Lar Berglund comments, from KTH—. Some light passes through the wood and makes the material transparent. “Some of the light is refracted and scattered at different angles and produces interesting effects in lighting applications.”

There are those who are also exploring the possibilities of creating it More resistant screens to smart phonesVehicles, billboards, or even insulated windows, a use that combines its transparency with a greater insulating capacity than glass. Thanks to this combination, buildings can retain heat or keep their interiors cool. Researchers have also tested for years the possibility of introducing various compounds into his “skeleton”, e.g Polly, beige. also BCMTo change the ability of wood to retain or release heat, allowing it to… Flow regulation That comes and goes.

“Promising future”. Sentence He is from Qiliang Fu, a wood nanotechnology scientist in Nanjing Forestry Universityin China, which explains this to Knowledge Magazine About the future of matter. His potential has already seen him move from academia to business. French WodoFor example, the possibilities of treated wood were explored for some time four years ago Highlighted by the European Commission It aroused interest in the automotive industry, with projects to integrate electronics into its wood and thus create “touch-screen dashboards”.

The European Union contributed $2.27 million to a project called Woodoo reinforced wood Which was activated “to transform wood into a building material as strong as concrete and as transparent as amber.”

the pictures: Celine Montanari (KTH), UMD And Xueming He et al (Annual Reviews)

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