Sustainability in materials science: the role of transparent wood

Ten years ago, combining the word "wood" with "transparency" was an oxymoron since wood, a well-known natural composite material, does not allow light to pass through: indeed, light undergoes remarkable scattering phenomena and is completely absorbed by wood. The possibility of making wood transparent was discovered in parallel by two research groups (one American and one Swedish). It resulted in a new material that combines transparency, lightness, impact resistance, and low thermal conductivity. In fact, the removal of lignin (one of the three main components of wood along with cellulose and hemicellulose) allows for the obtainment, after infiltration with a monomer that possesses a refractive index similar to that of delignified wood, of a material with the above characteristics. Further, when the infiltrated monomer is bio-sourced, it is possible to attain a material that has sustainability characteristics and fits perfectly into the current concept of circular economy. Nowadays, transparent wood is finding applications both as a structural and functional material. This chapter describes transparent wood, how it is obtained, and the most recent applications in advanced fields.