Less than two months ago, Swedish researchers reported how they had created transparent wood, which could be used to make biodegradable solar panels in future. An American team has now found an easy way to make the renewable material stronger than glass.
All that is required is a coating of epoxy, which makes the transparent wood not only stronger but also a better insulator, while allowing it to maintain its biodegradability.
Like the Swedish team, researchers from the University of Maryland, USA, first boiled pieces of wood for two hours in a mixture of water, sodium hydroxide and other chemicals. This process strips the wood of lignin - a component present in cell walls of wood and bark, which gives them the typical brownish colour.
When analysing the properties of the epoxy-infused transparent wood, the Maryland team found the structure of the material was maintained including the tiny channels that carry water inside a tree. These channels could be used after the treatment to carry light – a promising property that could pave the way for wood-based solar panels. In experiments, the researchers found that up to 90 per cent of the light shone on the wood-based material passes through. In a solar panel, these channels could be able to efficiently funnel light to the layer that converts it to electricity.
Among other possible applications, the researchers envision windows that would scatter light passing through them, thus making it impossible for people outside to make out what is happening inside the house.
Being extremely light and cheap, the material could also be used in various industrial applications, for example to build parts of vehicles or optical equipment.
First, however, the researchers would have to figure out how to scale up the production as they are currently only able to work with very small samples. The piece of epoxy-coated transparent wood described in an article of the latest issue of the journal Advanced Materials was only 13 by 13 cm thick.
The Swedish team originally coated the transparent wood with a polymer to give it back some of its resilience.