Enhancing interfacial properties of carbon fibers reinforced epoxy composites via Layer-by-Layer self assembly GO/SiO2 multilayers films on carbon fibers surface

To enhance the interfacial properties of carbon fibers (CFs) reinforced epoxy composites without sacrificing fiber strength. A facile and effective Layer-by-Layer (LbL) self assembly method was proposed to deposit graphene oxide/silica (GO/SiO 2 ) multilayers films onto CFs surface. The negatively charged GO and positively charged SiO 2 can be assembled on the surface of fiber based on electrostatic interactions. Surface microstructures of CFs were characterized systematically. Scanning electron microscopy (SEM) revealed the GO/SiO 2 multilayers films compact and homogeneous coverage onto CFs surface. This coverage significantly increases the roughness and surface energy of the fibers, improving the wettability and mechanical interlocking between fibers and resin. The optimal interfacial shear strength (IFSS) of composites with 5 layers (CF-L5) was 84.40 MPa, which increased by 86.1% compared to that of Untreated-CF composites (45.36 MPa), and the interlaminar shear strength (ILSS) of CF-L5 composites (76.34 MPa) increased by 89.3% compared to that of Untreated-CF composites (40.33 MPa). In addition, the flexural strength of CF-L5 composites (765.57 MPa) was 30.4% higher than that of Untreated-CF composites (587.19 MPa). The fractured surface, energy dispersive spectroscopy (EDS) mapping and dynamic mechanical properties of CFs composites also show a great improvement in interfacial adhesion. Moreover, the tensile strength (TS) of single fiber increased from 3.52 GPa to 3.68 GPa after LbL assembly of GO/SiO 2 . Our work suggested that such LbL self assembly is a green and promising approach toward preparing high interfacial properties in CFs composites.