Preparation and Properties of Octadecylamine Modified Carbon Nanotubes

Abstract

Carbon nanotubes (CNTs) have become an ideal reinforcement filler for polymer composites due to their unique one-dimensional hollow structure and excellent mechanical properties. However, the chemical inertness and easy agglomeration of the CNTs' surface limit their wide application. In this paper, the "oxidation amidation" two-step method was used to modify the surface of multi-walled carbon nanotubes. Firstly, carboxyl active sites (O-CNTs) were introduced on the surface of CNTs by hydrogen peroxide oxidation, and then octadecylamine was grafted onto the surface of CNTs by amide reaction with 1,1'-carbonyl diimidazole (CDI) as an activator to prepare hydrophobic functionalized carbon nanotubes (A-CNTs). The structure, morphology, and surface properties of CNTs before and after modification were systematically characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and contact angle test. The results showed that the oxidation treatment successfully introduced oxygen-containing functional groups such as carboxyl groups on the surface of CNTs, and octadecylamine was covalently grafted to the surface of CNTs through amide bonds, and the nitrogen element was evenly distributed after grafting; XRD analysis showed that the main crystal structure of CNTs was not destroyed during the modification process; The contact angle test showed that the contact angle of the original CNTs was 98.2°, the O-CNTs after oxidation was 107.1°, and the A-CNTs after octadecylamine modification increased to 137.9°, realizing the transition from hydrophobic to strong hydrophobic.