Highly Strong Yet Flexible Polyacrylate Composites Reinforced with Bamboo Macrofiber via Dynamic Metal‐Linker Bonds

Abstract Soft fiber‐reinforced polymers (SFPs), composed of the polymer matrix combined with reinforcing fibers, are widely used across various industries due to their high tensile strength when subjected to bending or twisting. However, the existing SFPs often face a trade‐off between mechanical strength and flexibility, which significantly limits their potential applications. Herein, an innovative interfacial regulation strategy based on dynamic bond cross‐linking is presented to produce SFPs with both ultrahigh strength and unprecedented flexibility. This approach involves embedding highly aligned bamboo macrofibers within a polyacrylate matrix, resulting in soft composites that maintain impressive strength. Incorporating dynamic Zn─O bonds at the bamboo macrofiber‐polyacrylate interface enables reversible transitions between associative and dissociative states, effectively modulating interfacial strength and preventing delamination. Furthermore, the intrinsic flexibility and aligned microstructure of the bamboo macrofibers promote efficient stress transfer and dissipation, enhancing both the strength and flexibility of the composite. As a result, the resulting SFPs exhibit a remarkable mechanical strength of 161 MPa and superior flexibility (322 MJ m − 3 ), capable of withstanding bending and twisting up to 180°. These properties open up new possibilities for practical applications in safety protection technologies, such as airbag systems and seat belts.