Abstract
Electrochemical oxidation of ω‐diamines on carbon fibers allows the bonding of these molecules to the carbon fibers. The conditions leading to this surface modification are described, and the influence of the different parameters is discussed. The structure of the bonded layer is studied by voltammetry, XPS, and SIMS. A mechanism is proposed which involves the coupling of a radical cation to the fiber. Toughness of carbon‐epoxy composites is improved when prepared from these modified fibers.