Tough and UV-resistant biodegradable polyurethane elastomers based on extracted lignin and treated wood flour

Polyurethanes are widely utilized across various fields. In the pursuit of sustainable development, current research prioritizes the development of bio-based, environmentally friendly polyurethanes. Wood flour, a type of biomass waste, faces significant challenges in achieving high-value utilization. In this study, wood flour was pretreated with sodium hydroxide solution to generate extracted lignin (Elig) and alkali-treated wood flour (AWF), which were subsequently employed to fabricate biodegradable polyurethane elastomers. Elig was further modified with polycaprolactone (PCL) to enhance its reactivity and flexibility, serving as a biological macromolecule crosslinker in the synthesis of lignin-based polyurethane [PU(Plig)]. Tough polyurethane composite elastomers were then obtained by incorporating AWF into PU(Plig). The resulting PU composite elastomer, PU(Plig@AWF), containing strong interfacial interaction between Elig and AWF, exhibited high toughness (188.15 MJ/m³), excellent UV resistance (with stress and strain retention rates of 77.92 % and 77.07 %, respectively, after 96 h of ultraviolet aging), and outstanding biodegradability (with a mass loss of 19.06 % observed after 50 days of soil degradation testing). Additionally, leveraging the unique characteristics of lignin and wood flour (WF), the elastomer demonstrated remarkable light/thermal-electric conversion capabilities, effectively powering a fan. This study advances the development of biomass-based, multifunctional polyurethane elastomers with enhanced cost-efficiency.