Layer-by-layer assembled nacre-like polyether amine/GO hierarchical structure on carbon fiber surface toward composites with excellent interfacial strength and toughness

Inspired by nacre's sophisticated "brick-and-mortar" structure, multilayered polyether amine (PEA)/graphene oxide (GO) hybrid building blocks were incorporated onto the surface of carbon fiber via Layer-by-Layer (LbL) assembly to strengthen and toughen the interphase of composites. Impressive improvements of 67.7% and 129.0% in interfacial strength and toughness over those of untreated fiber composites are achieved for composites with 9 layers of PEA/GO on fiber surface. The synergistic effects stemming from covalent bonds, hydrogen bonds and pi-pi interaction, as well as crack deflection caused by homogeneous GO layers, improved surface energy and wettability are major reasons for the increase in interfacial adhesion. The major toughening mechanisms are attributed to interfacial micro-cracks, viscoplastic energy dissipation of PEA and GO slippage. This work provides a promising route of bio-inspired structural composites with excellent strength and toughness.