Solvent-triggered dissolution-gelation for multiscale structural densification of lignocellulosic biocomposites

Solvent-triggered dissolution–gelation enables adhesive-free lignocellulosic bonding. • Multiscale densification achieved via localized cellulose–lignin reconfiguration. • Densified biocomposites exhibit tensile strength surpassing metal alloys. • Versatile and scalable route for sustainable, high-performance biomass-based material Lignocellulosic biomass is an abundant and sustainable resource for structural materials; however, achieving high mechanical performance without chemical treatments or synthetic adhesives remains a significant challenge. In this study, we present a solvent-triggered dissolution–gelation strategy that enables the in situ bonding of lignocellulosic strips into adhesive-free, structurally integrated biocomposites with hierarchical densification. This method induces the localized dissolution and gelation of cellulose, hemicellulose, and lignin under mild solvent conditions, promoting the reconfiguration of hydrogen bonding networks and transformation of crystalline structures, while simultaneously filling micro- and nanoscale voids. This results in multiscale structural densification from the molecular to the micro- and macro-scales. The resulting densified biocomposites exhibit a specific tensile strength of 823.0 MPa·cm 3 ·g −1 , significantly higher than that of conventional alloys and surpassing values reported for similar materials. In addition, the shear adhesion strength reaches approximately 20 MPa, greatly outperforming conventional adhesive-bonded laminates. Importantly, this strategy preserves the natural lignocellulosic composition, eliminating the need for selective component removal and thus minimizing chemical waste and environmental impact. Moreover, the approach shows potential versatility across several representative lignocellulosic feedstocks, including bamboo, sugarcane bagasse, pulpboard, red oak, and pine, and can be implemented under ambient conditions. This method provides a scalable, environmentally sustainable pathway for producing high-strength, lightweight materials from natural biomass, offering a promising alternative to petroleum-based composites in sustainable materials engineering. Download: Download high-res image (266KB) Download: Download full-size image