Sustainable high-strength macrofibres extracted from natural bamboo

Synthetic fibres such as polyester and carbon are used in a broad variety of industries. However, as they derive from petrochemicals that are neither renewable nor biodegradable, the development of natural alternatives has gained increasing momentum in recent years. Here, we report a top-down approach for scalable production of cellulose macrofibres from bamboo stems involving a mild delignification process followed by water-assisted air-drying. Consisting of aligned and densely packed cellulose nanofibrils that possess strong hydrogen bonds and van der Walls forces, the extracted fibres exhibit a tensile strength of 1.90 ± 0.32 GPa, a Young’s modulus of 91.3 ± 29.7 GPa and a toughness of 25.4 ± 4.5 MJ m−3, which exceed those of wood-derived fibres and are comparable to synthetic carbon analogues. As a result of the low density, the specific strength is as high as 1.26 ± 0.21 GPa cm−3 g−1, surpassing most reinforcing components such as steel wire, synthetic polymers and vitreous fibres. The life-cycle assessment reveals that replacing polymer and carbon fibres in structural composites with the current natural fibres leads to substantial reduction in carbon emissions. Our work suggests a pathway towards sustainability in wider areas of application, including automobiles, aeronautics and construction.