Multifunctional epoxy/carbon composites with a fully reparable interface

In this work, for the first time, carbon fibers (CFs) were coated with nanosized‐polycaprolactone (PCL) particles to obtain a functionalized self‐healable interphase, capable to fully recover the pristine interfacial shear strength with a debonded epoxy matrix. PCL nanoparticles were initially water‐dispersed at different concentrations and deposited on CFs by electrophoretic deposition. The application of various voltage levels resulted in different morphologies of the coating. Epoxy microdroplets were deposited and cured on neat and PCL‐coated fibers. After complete interfacial debonding by microdebonding tests, an electric current was applied on CFs to activate a thermal interfacial healing by Joule effect. The healing efficiency was estimated as the ratio of interfacial shear strength measured before and after healing. An outstanding repairing efficiency was obtained upon thermal mending with a complete recovery of the original interfacial shear strength, thus indicating a strong potential of the PCL nanocoating as interfacial healing agent for composite structures. Highlights CFs were coated with nanosized‐PCL particles to obtain a functionalized self‐healable interphase. Electrophoretic deposition was employed for the fiber coating. Microdebonding tests were performed to assess the fiber/matrix interfacial properties in terms of interfacial shear strength. A full recovery of the interfacial properties was obtained via thermal interfacial healing by Joule effect. Preparation and test of samples, (1) synthesis of PCL nanoparticles, (2) deposition of PCL nanoparticles on CF via electrophoretic deposition, (3) morphological analysis of neat and PCL‐coated CF, (4) evaluation of interfacial self‐healing via micro‐debonding test.