High Performance, Fully Bio‐Based, and Optically Transparent Wood Biocomposites

Abstract

The sustainable development of engineering biocomposites has been limited due to a lack of bio‐based monomers combining favorable processing with high performance. Here, the authors report a novel and fully bio‐based transparent wood biocomposite based on green synthesis of a new limonene acrylate monomer from renewable resources. The monomer is impregnated and readily polymerized in a delignified, succinylated wood substrate to form optically transparent biocomposites. The chemical structure of the limonene acrylate enables diffusion into the cell wall, and the polymer phase is both refractive index‐matched and covalently linked to the wood substrate. This results in nanostructured biocomposites combining an excellent optical transmittance of 90% at 1.2 mm thickness and a remarkably low haze of 30%, with a high mechanical performance (strength 174 MPa, Young's modulus 17 GPa). Bio‐based transparent wood holds great potential towards the development of sustainable wood nanotechnologies for structural applications, where transparency and mechanical performance are combined.

Sustainable Wood Nanotechnologies for Wood Composites Processed by In-Situ Polymerization

“…The biobased transparent wood was prepared via green delignification treatment (peracetic acid) followed by solvent-free succinylation (succinic anhydride derived from biobased succinic acid). A bio-based limonene acrylate monomer, designed from renewable limonene oxide (derived from limonene) and acrylic acid (derived from lactic acid), was impregnated and polymerized inside the wood substrate (Montanari et al, 2021).…”

“…This is important, since solvent-assisted monomer impregnation should be avoided in sustainable industrial production of wood composites. The fully bio-based transparent wood biocomposites showed improved optical and mechanical properties, due to high polymer modulus and excellent matching of the refractive index of cellulose (Montanari et al, 2021). Other functionalization strategies have been used to tailor plant fiber properties.…”

“…The bio-based transparent wood biocomposite design in Figure 3B exemplifies the impregnation and polymerization of a bioderived monomer into a functionalized wood substrate. The limonene acrylate monomer can diffuse into the modified cell wall and polymerizes readily, resulting in high optical transmittance, low haze, and a high strength composite (Montanari et al, 2021). The resulting biocomposite product is a good candidate for sustainable wood nanotechnology.…”

Prospects and Applications of Biomass-Based Transparent Wood: An Architectural Glass Perspective

“…One of the challenges is to replace fossil polymers in the manufacture of sustainable TW. Recently, Montanari et al (2021) have successfully developed an environmentally friendly alternative: limonene acrylate, a monomer made from limonene. A substance extracted from orange juice is used to make a polymer that restores the strength of the delignification and allows light to pass through, producing BBTW.…”

“…For example, the epoxy resin as impregnating material is free from irritating odor. Recently, Montanari et al (2021) have successfully developed an environmentally friendly alternative: limonene acrylate, a monomer made from limonene. Besides, the biomass used as raw materials have the advantages of being very widely sourced, green and renewable, which are in line with the trend of sustainable development.…”