Wood is currently seeing a renaissance as a building material, which is mainly due to the growing awareness of environmental concerns. It is renewable, sustainable and the increased reforestation to meet the demand from the construction and furniture industries is helping to counteract the rising CO2 levels in the atmosphere. Wood absorbs large quantities of water particularly via the end grain and wet wood is susceptible to rot and mould. To counteract this, we developed a sustainable hydrophobic coating based on chitosan from food-industry waste. The novelty is that the coating is applied from aqueous solutions and polymerises on the wood surface, whereby the chitosan chains are cross-linked to form a water-insoluble film. The films are transparent, approx. 0.5 mm thick, accentuate the wood grain, strongly adhere to the wood surface, and completely seal the end grain with contact angles of approx. 93°.[1] Mayonnaise and coffee can be removed completely from the coated surfaces, only red wine leaves a stain, but much less pronounced than on untreated wood. The coating also offers protection against UV-induced degradation, as no yellowing is observed under irradiation for four weeks. Moreover, freestanding, polymerised chitosan itaconate films were found to be non-flammable and do not melt when exposed to fire.[2] When applied to wood surfaces, the coating delays the ignition and the spreading of flames. A single application already reduces the burning rate by one third. With multiple layers of the coating, the samples extinguish as soon as the external flame is removed (Fig. 1).

The growing awareness of society towards major environmental challenges is driving the polymer industry to develop greener and more sustainable products. One approach to achieving this goal is by replacing petroleum-based building blocks with bio-based alternatives. Lignin is a promising bio-aromatic resource that could provide interesting properties when integrated into coatings, composites, and prepolymer components.
Herein, we report a new class of photo-curable resins derived from depolymerized lignin oil, an emerging class of bio-oil containing low molecular weight bioaromatic compounds such as lignin monomers, dimers, and small oligomers. To do so, we developed a two-step green synthetic pathway involving ethoxylation of phenolic hydroxyls with ethylene carbonate, followed by trans-esterification of aliphatic hydroxyls with methyl methacrylate. This innovative approach was first applied to monomeric (hydroxy)alkylphenol model compounds and then directly to pinewood-derived lignin oil, circumventing the use of traditional (and often toxic) acrylation reagents. Highly functionalized methacrylated bioaromatic precursors were obtained directly as viscous liquids (without adding reactive diluents), thus mimicking the acrylic “syrups” commonly used in industry. These reactive biosyrups were then UV-cured into functional materials, such as free-standing films and nanoscale coatings. Moreover, their superior thermo-mechanical properties, such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile properties, were thoroughly investigated, revealing important insights in their tunable structure-property relationships.

Transparent wood is a very innovative composite material derived from natural wood by removing or modifying its lignin and infusing it with a transparent polymer whose refractive index is similar to that of cellulose fibers (approximately 1.53). The resulting material is not only transparent to visible light but also strong, lightweight, and potentially exhibits superior thermal insulation compared to inorganic glass. As such, transparent wood offers exciting possibilities for eco-friendly building materials, interior design, and energy efficiency.¹ ²
In this study, we produced transparent wood composites from fir using a two-step process: bleaching, polymer infiltration, and curing. We propose a novel bleaching method employing Na₂CO₃∙1.5H₂O₂ under mild conditions, which effectively whiten lignin while preserving structural integrity. Chemical modifications, including lignin and hemicellulose loss, were confirmed by using ATR FT-IR spectroscopy. The delignified templates were then infused under vacuum with poly(methyl methacrylate) or epoxy resin to obtain a clear durable composite. Depending on the experimental conditions, the resulting transparent wood can retain the wood’s natural grain pattern.
Furthermore, we extended the process to wood particles and sawdust—a waste product of fir timber—yielding loose cellulose fibers suitable for blending with polymers at different ratios. The transparent wood optical properties (haze and luminous transmittance), mechanical performance (three-point bending test), and morphology (via SEM) were characterized. Additional physicochemical properties, including thermal stability, wettability, and solvent absorption, were also evaluated.