Self-reporting damage and enhancing interfacial properties of carbon fiber composites via self-assembly host-guest mechanochromic fluorescent probe

Abstract

Structural health monitoring (SHM) of carbon fiber reinforced polymer (CFRP) composites under dynamic or static overloading was essential to assure safety and service life. Herein, perylenediimides-γCyclodextrins (PDI-γCD) inclusion complex was first designed by self-assembly host-guest method and used as mechanochromic fluorescent probe to construct a novel carbon fiber (CF@PDI-γCD) interphase, and the interfacial self-reporting damage as well as interface property and reinforcing mechanism of CFRP composites were investigated. PDI-γCD was tailored by N⋯O–H hydrogen bonding between PDI and the cavity of γCD, and the fluorescence switching-on of PDI-γCD was observed under mechanical force. The chemical activity and roughness of CF@PDI-γCD surface were increased. The CF@PDI-γCD surface exhibited slight fluorescence instead of non-fluorescence on CF-pristine and CF-commercial surface, and the green fluorescent change in the interfacial regions was monitored due to the mechanochromic switching-on of PDI-γCD, indicating the micron-scale damage of CF@PDI-γCD composites. The interfacial shear strength (IFSS) of CF@PDI-γCD composites was much higher than that of CF-pristine and CF-commercial composites, which was attributed to synchronous enhancement of mechanical interlocking and chemical bonding between PDI-γCD and epoxy matrix. Consequently, this work presented a potential application in synergistically monitoring damage and enhancing interfacial properties of CFRP composites.