A surpassingly stiff yet lossy multiscale nanocomposite inspired by bio-architecture

Common microstructural features inspired by bones, including the moduli-mismatching interface and the intramolecular dangling chains, are employed in designing and fabricating our bio-inspired nanocomposite in order to defeat the conflict of stiffness versus damping. The epoxy vitrimer is itself chosen to construct the intramolecular dangling chains, and then mixed with multi-walled carbon nanotubes (MWCNTs) to form the moduli-mismatching interface. Experimental and theoretical research is performed to elucidate the role of the common microstructural features on the damping of our bio-inspired nanocomposite. Dangling chains improve damping, although they are negative for moduli. The high modulus of MWCNTs not only enlarges the modulus of composites but also causes a stress jump phenomenon at the interfacial zone, which induces the irreversible production process of inelastic strain at the interface to dissipate mechanical energy. The loss modulus of MWCNTs-reinforced epoxy nanocomposites is found to reach as much as 738 MPa, which exceeds the limit of 600 MPa for traditional materials (including bones), although the common microstructural features are inspired by bones. The synergistic enhancement mechanism caused by the intramolecular dangling chains and the moduli-mismatching interface is responsible for the surpassingly stiff yet lossy performances.