Bioinspired supramolecular stress buffer between carbon fiber and epoxy resin for high interfacial performances and toughness of composites

Abstract

Carbon fiber reinforced polymer composites (CFRPs) possess contrastingly high strength but low toughness, which limits their application under special circumstances, such as high stress, cryogenic temperatures, or vibration. The chemical inertness and smooth surface of carbon fiber (CF) are the main reasons behind the low toughness of CFRPs, characterized by poor interfacial performances, including low strength and low toughness. Biological organisms possess structures or chemical compositions that contribute to exhibiting strong interfacial adhesions. Herein, we construct a mussels-inspired supramolecular stress buffer (i.e., Fe(III)-tannic acid buffer, Fe-TA buffer) on CF to distribute stress and improve the interfacial performances and toughness of CFRPs. The Fe-TA buffer can improve interfacial performances by rough biomimetic interfacial structure, introducing multiple supramolecular interfacial interactions and improving interfacial wettability, ultimately resolving the common issue of low toughness in the CFRPs. In the presence of Fe-TA buffer, the interfacial shear strength (IFSS) value and mode II critical strain energy release rate (G_IIC) value are enhanced by 17.0% and 41.8%, respectively. This research provides a design for a stress buffer between resin matrix and inorganic enhancer which results in high interfacial strength and toughness.