Industrial Lignin Upcycled to High-Performance, Cost-Competitive Bio-based Adhesives via Green Ion-Exchange Self-Catalytic Strategy.

The global pulp industry discards over 50 million tons of lignin annually, with conventional valorization strategies hindered by performance and cost barriers. We report an ion-exchange, self-catalytic strategy to upcycle the industrial lignosulfonate into high-performance bio-based adhesives. The facile ion-exchange process transforms sodium lignosulfonate into lignosulfonic acid, which acts as not only a copolymer backbone of adhesive but also an intrinsic macromolecular catalyst, autonomously driving esterification reaction with citric acid and then wood polymers, eliminating the need of fossil-derived cross-linkers and energy-intensive pretreatments. This mechanism endows it performing excellent performance in bonding strength and boiling-water resistance. Crucially, the performance gains are coupled with important economic and environmental benefits; production costs are substantially lower than conventional petrochemical resins, and a life cycle assessment confirms markedly reduced environmental impacts alongside negligible formaldehyde emissions. This work successfully resolves the performance-sustainability-cost trade-off, establishing a waste-to-wealth pathway for circular manufacturing.