Constructing a simple anti-sandwich structure on carbon fiber surface for simultaneously strengthening and toughening the interphase of epoxy composites

A simple anti-sandwich structure that employs strong, stiff and tough graphene oxide as the core layer, flexible polyether amine as the wrapping connection faces is constructed on carbon fiber surface via chemical grafting approach to strengthen and toughen the interphase of epoxy composites. Impressive 94.4% and 48.7% increments in interfacial toughness and interfacial shear strength are achieved in composites with anti-sandwich structure on fiber, by analogy to those of untreated fiber composites. Pertinent strengthening reasons are mainly enhanced surface energy and the hybrid molecular entanglement. Probable toughening mechanisms include crack deflection by GO core layer, appropriate chemical bonds at interphase, plastic deformation of polyether amine and interfacial friction between adjacent layers due to the build of anti-sandwich structure, as well as the localized toughening effect of the matrix. This work provides a promising thought to obtain advanced composites with excellent strength and toughness.