Sustainability and Circularity of Transparent Wood: The Role of the AI-TranspWood Project in Highlighting the Potential of this New Material

The current challenge toward the development of more sustainable processes and the design of low environmental impact and efficient materials is having a significant impact on the academic and industrial communities. In this context, the design, implementation, and application of novel polymer-based systems that can directly be obtained from available biomasses (without impacting other supply chains, like the food-related ones), by using “green” technologies is currently becoming necessary and demanding, also for fulfilling the circular economy concept. The latter is perfectly matched by wood, a renewable and recyclable biomass that has massively been employed by mankind over the centuries. Wood is a natural composite material with unique mechanical, thermal, and environmental properties, which make it appropriate for several applications dealing with civil engineering, art, household uses, and business uses (including furniture, stationery, shipbuilding, and fuel).Nonetheless, wood exhibits a complex hierarchical structure that accounts for a high anisotropy, due to the presence of open channels aligned in the growth direction, and a peculiar micro-, meso-, and macro-porosity. As a result, it is an opaque material in which the lignin (one of the three main constituents together with cellulose and hemicellulose) favors the occurrence of light- scattering phenomena. Though the idea of making wood a transparent material (“Transparent Wood”, TW) dates to 1992, it was rediscovered and implemented only during the last fifteen years. Besides, it is now possible to provide TW not only with high optical transmittance but also with other characteristics comprising environmental protection, flame retardance, photoluminescence, and energy storage capability, among others. As a consequence, at present TW is reasonably considered a novel, green, and smart “building block”, suitable for the design of both structural and functional systems to be exploited in such key- performing sectors as optoelectronics, photovoltaics, buildings, furniture, and automotive.