With Co-MOFs as an oxidase-mimicking nanozyme, the AR oxidized product, non-fluorescent resazurin could be reduced to fluorescent resorufin by l-cysteine, which is specifically applied for fluorescence “turn-on” detection of l-cysteine.

The 3D structure hybrids obtained by combining CNT and epoxy functionalized GO exhibit an obvious synergistic effect on the improvement of mechanical properties of epoxy composites.

In order to improve the interfacial properties of graphene oxide (GO) and epoxy resin (EP), hyperbranched polyesters with terminal carboxyl (HBP) non-covalently functionalized graphene oxide (HBP-GO) was achieved by strong π-π coupling between hyperbranched polyesters and GO nanosheets. The effects of non-covalent functionalization of GO on the dispersibility, wettability and interfacial properties were analyzed. The mechanical properties and enhancement mechanism of HBP-GO/EP composites were investigated. The results show that the hyperbranched polyesters is embedded in the GO layer due to its highly branched structure, which forms the steric hindrance effect between the GO nanosheets, effectively prevents the agglomeration of GO nanosheets, and significantly improved the dispersibility of GO. Simultaneously, the contact angle of HBP-GO with EP is reduced, the surface energy, interfacial energy and adhesion work are increased, then the wetting property of HBP-GO is significantly improved. The main toughening mechanism of HBP-GO is microcrack deflection induced by HBP-GO and plastic deformation of the EP matrix. In the microcrack propagation zones, HBP-GO may produce the pinning effect near the microcrack tips and change their stress state, resulting in microcrack deflection and bifurcation. So, the microcrack propagation path is more tortuous, which will consume much more fracture energy. Therefore, the mechanical properties of the HBP-GO/EP composites are greatly improved.

Carboxylated and aminated graphene oxide (CGO and AGO) were first prepared by using carboxyl-terminated aromatic hyperbranched polyester (HBPC) and amino-terminated aromatic hyperbranched polyester (HBPA) noncovalent functionalized GO, respectively. Subsequently, multiscale reinforcing fibers (CGO-PDA-AF and AGO-PDA-AF) were prepared by exploiting the super adhesion of the polydopamine layer (PDA) and its physical adsorption and chemical grafting with the CGO and the AGO. This study examined the tensile strength of the modified aramid fiber (AF) monofilament and the interfacial shear strength (IFSS) between the modified AF monofilament and the EP matrix, and an investigation was conducted on the interfacial enhancement mechanism. As indicated from the results, the AGO exerted a more effective modifying effect than the CGO. The single filament tensile strength and IFSS of the AGO-PDA-AF were the maximum (4.66 GPa and 96.2 MPa), nearly 8.6 and 7.9% higher than those of the CGO-PDA-AF, respectively. The enhancement of the interface performance between the AGO-PDA-AF and the EP was attributed to the introduction of considerable amino active groups in the AGO, thereby forming a stable covalent bond with the epoxy matrix, which significantly improved the interface bonding strength. Moreover, the flexible coating layer formed by the AGO could reduce the stress concentration of the interface through deformation, so the AF could be carried more uniformly. Furthermore, the AGO increased the surface affinities of the AF and improved the mechanical interlocking with the EP matrix.

No abstract