From biomass to bonding: The rise of lignin nanoparticles in wood adhesives-A review

Lignin nanoparticles have emerged as a promising bio-based nanomaterial for enhancing the performance of wood adhesives, offering a pathway toward sustainable alternatives to petroleum-derived resins. This review synthesizes advances in lignin nanoparticle production, surface functionalization, and application in wood adhesive formulations. Studies consistently report that incorporating 3–5 wt% lignin nanoparticles can increase adhesive shear strength by approximately 20–30% and improve thermal stability by 10–15 °C relative to conventional phenol-formaldehyde resins. Lignin nanoparticles also enhance curing kinetics and reduce formaldehyde emissions by up to 50%, underscoring their potential to meet both performance and environmental targets. Remaining challenges include source heterogeneity, nanoparticle dispersion, and the need for industrial-scale standardization. By consolidating current progress and mapping future research directions, this review highlights the pivotal role of lignin nanoparticles as a sustainable, high-performance alternative to petroleum-based adhesives. It outlines a roadmap for translating laboratory findings into scalable, industrial solutions. • Nano-lignin upgrades lignin into a high-value, sustainable nanomaterial. • Enhanced reactivity boosts bonding strength and durability in wood adhesives. • Surface-functionalized nano-lignin enables formaldehyde-free formulations. • Green synthesis methods improve scalability and align with the circular bioeconomy. • Nano-lignin advances eco-friendly adhesives, replacing petroleum-based resins.