Out of many natural materials, bamb

Out of many natural materials, bamboo offers significant structural and environ- mental advantages given its rapid growth, moisture resistance, climate tolerance, and structural rigidity. Bamboo grows rapidly and can be harvested every 3–5 years, well- exceeding the 20–60 years growth cycle of traditional timber used in structural applications.[20] Across Asia, America, and Africa, there are over 1500 recognizedspecies of bamboo with an estimated growing area of 36 million hectares. Traditional bamboo is a low-cost and abun- dant material that has been widely used in furniture, buildings, and bridges sincethe tensile strength of mature bamboo is comparable to mild steel.[21] Recently, tremendous efforts have been devoted toprocessing bamboo into sustainable, eco-friendly, cost-effective, and high-performance composite materials. Pre-treatment with bleaching, saturated steam, hot oil, or by filling with resin fol- lowed by densification, has led to the enhanced mechanical per- formance of natural bamboo.[22–28] However, the improvement of the mechanical strength is moderate, generally achieving a tensile strength of 200–300 MPa and flexural strength of 100–320 MPa[29] (Tables S1 and S2, Supporting Information), which is mainly due to the natural brittleness of the lignin network and inefficient load transfer caused by weak interface interactions between the sclerenchyma and parenchyma cells and the existence of numerous defects. The mechanical tensile strength of engineered bamboo is 10–20-times lower than the theoretical mechanical strength of elementary cellulose fibril(7.5 GPa),[30] leaving significant room for further improve-ment. Thus, it remains a challenge to design and fabricate bamboo materials with both high mechanical strength and toughness at bulk scale.