Remarkably improved interfacial adhesion of pitch-based carbon fiber composites by constructing a synergistic hybrid network at interphase

Ultralow interfacial adhesion of pitch-based carbon fiber composites has always a disturbing problem in reality since the fiber surface is of high graphite degree. Herein, a novel strategy for remarkably increasing the interfacial shear strength (IFSS) of composites via incorporating silane coupling agent (APTES)-polydopamine (PDA) -polyether amine (PEA) ternary organic materials on fiber surface is reported. Due to the solid connection of pitch-based carbon fiber with APTES-PDA-PEA through previous carboxylation and hydroxylation, as well as the increased surface energy and improved wettability, a synergistic hybrid network is formed at the interphase, where various interfacial interactions, including covalent bonding, hydrogen bonding, π-π conjugated bonding and intermolecular entanglement, cooperate with each other. The IFSS of modified fiber composites exhibits an amazing 427.7% increase, much higher than publicly reported pitch-based carbon fiber composites (20.3%~235.1%). The findings in this article offer a unique insight on the design of synergistic hybrid bridging transition strategy addressing the weak interphase in pitch-based carbon fiber composites.