Valorizing wood processing waste into an all-natural bulk structural material

Natural wood, re-engineered at the nanoscale, is emerging as a promising lightweight structural material. To fully harness its potential, it is essential to upcycle the growing volumes of waste generated during bulk wood processing. Here, the selective removal of hemicellulose from wood powder particles is achieved through a mild and simple chemical treatment, effectively overcoming challenges associated with hemicellulose, such as high water absorption and thermal instability, thus enabling the engineering of cell wall fragments into micro-nano building blocks. An efficient “oriented concentrating assembly” strategy is proposed to assemble these building blocks into a unique upcycled wood with layered “flake-and-filament” structures. The resulting upcycled wood outperforms typical conventional petroleum-based polymers in terms of high flexural strength (180 MPa), high flexural stiffness (11 GPa), high toughness (1.1 kJ m −2 ), high thermal conductivity (0.48 W m −1  K −1 ), and low coefficient of thermal expansion (17 × 10 −6  K −1 ), along with enhanced fire retardancy. Together with the all-natural characteristics, the obtained upcycled wood exhibits considerable potential as a high-performance, lightweight structural material for plastics replacement.