Transparent Wood-Based Materials: Current State-of-the-Art and Future Perspectives

Human history is largely characterized by the massive use of wood, the most well-known natural composite material, possessing unique thermal, mechanical, and environmental features that make it suitable for several applications, ranging from civil engineering, art, and household uses, to business uses (including furniture, stationery, shipbuilding, and fuel). Further, as a renewable and recyclable biomass, wood perfectly matches the current circular economy concept. However, because of its structure and composition, wood is not transparent: therefore, the possibility of removing the embedded lignin, hence limiting the light-scattering phenomena, has been investigated over the last ten to fifteen years, hence obtaining the so-called "transparent wood (TW)". This latter represents an up-to-date key material, as it can be utilized as obtained or further functionalized, combining the transparency with other features (such as flame retardance, energy storage ability, and environmental protection, among others), which widen the potential (and practical) applications of wood. The present manuscript aims at summarizing first the current methods employed for obtaining transparent wood, and then the latest achievements concerning the properties of transparent wood, providing the reader with some perspectives about its novel functionalizations and applications.