Development of bio-based and recyclable components from sustainable feedstocks for printed electronics

To meet climate goals and reduce reliance on fossil resources, the development of circular and bio-based materials is essential, especially in sectors like electronics, which generate high environmental pressure and significant amounts of electronic waste. In this context, we present a three step organosolv fractionation process applied to lignocellulosic biomass (beech wood) to improve lignin quality while enabling full feedstock valorization. The process achieved 71% delignification, with lignin recovery yields of 65%, comparable to the conventional one-step method. However, structural analysis revealed significantly better preservation of native lignin features: β-O-4 content reached up to 30 linkages per 100 aromatic units (vs. 7.3 in the one step process), with lower condensation (Hibbert’s ketones: 0.7–3.6/100 ArU). GPC data showed 35% lower molecular weight and enrichment in low-MW fragments (0–750 Da), improving lignin's downstream potential. Additionally, 77% of hemicellulose sugars and 87% of cellulose were retained in the solid pulp. The lignin-rich pulp, containing 13–17% residual lignin, was processed into lignocellulosic nanofibrils (LCNF) and used to fabricate printed circuit board (PCB) substrates. Despite 34.2% water uptake, the material showed robust mechanical properties (Young’s modulus: 10.2 ± 0.5 GPa at 50% RH) and supported the creation of a functional demonstrator device. These findings highlight the process as a viable route for producing high-quality lignin and circular electronics components from renewable feedstocks. Lignin was modified with functionalisation agents (carboxyl group donors) to form a covalent adaptable network (CAN) able to respond to stimuli like heat that allows polymer recycling. In this way, functionalized lignin was cured with liquids epoxies to form a solid reprocessable bisphenol A-free epoxy resin for coating applications. The epoxy resin formulations developed have a content of lignin of around 50 % in weight. Moreover, the epoxy resins showed tensile strength 20 %. Finally, the obtained epoxy resins showed high thermal stability (>345°C) and self-healing properties by hot-pressing.