A Universal Surface Modification Method of Carbon Nanotube Fibers with Enhanced Tensile Strength

Abstract We propose a new surface treatment method for carbon nanotube fibers (CNTFs) to attach desired functional groups with enhanced tensile strength. The proposed method consists of two steps: the first step is to introduce carboxyl groups, and the second step is a reaction with aniline derivatives to introduce the desired functional groups. Carboxyl groups, amine groups, and fluoromethyl groups introduced on the surface of CNTF were confirmed by X-ray photoelectron spectroscopy. After surface treatment the specific strength of the CNTF reached a maximum of 2.87 GPa/(g/cm3). The surface-treated CNTF exhibited different behavior in terms of resin infiltration and influenced the interfacial shear strength (IFSS) between fibers and resin. When the amine group was introduced through the two-step reaction, the IFSS value was more than twice of that of the as-prepared CNTF. This report provides guidelines for the preparation of CNTFs with tailored surface characteristics for composites and various applications.