(165d) Functionalization Multi-Walled Carbon Nanotube and Its Bismaleimide Composites of Properties

Carbon Nanotubes(CNTs) are unique nanostructured materials with remarkable physical, mechanical, chemical and electronic properties. Theses properties make them attractive for applications in many scientific and technological fields such as electronic structures, polymer composites, and biological systems. CNTs/polymer nanocomposites have attracted considerable attention by scientists in resent years. However, the limited ability to process and disperse in organic solvent CNTs hinders the realization of their full potential. To overcome this obstacle, surface modification of CNTs was very important in polymer application.

In our present work, at first fluorinating multi-walled carbon nanotubes (F-MWNTs) was synthesized by solid-phase method which an organic fluoride (PTEF) and multi-carbon nanotubes (MWNTs) were heated to 480-500C⁰for 4h. As a comparison, raw MWNTs and F-MWNTs have been characterized by using FTIR, XRD, XPS, SEM, TEM and TGA. The results showed that C-F bonds were created on the side wall of carbon nanotubes, successfully synthes is fluorinated MWNTs. The mole contents of fluorin atom can be reached 3.59 mol%. Then the F-MWNTs was put into excessive 1,2-diaminoethane (DME) in order to get amino-functionalization of MWNTs(NH₂-MWNTs). The reaction mixture was stirred under a nitrogen atmosphere for 6 h at 90-100C⁰ in the presence of pyridine as a catalyst. The FTIR, XRD, XPS, SEM, TEM, TGA methods were also used for characterization of NH₂-MWNTs.The result showed that amino groups covalently attached to their side walls C-F bonds, and the C-F bonds were replaced by C-N bonds. The new fluorinating technology of a solid-phase method had many advantages, such as simplicity, speedy and safety, compared with the usual gas-phase method which taken strong poisonous fluorine gas as the main raw material.The new fluorinating method was important significant for improving wide applications of carbon nanotubes. The NH₂-MWNTs could form stable suspension solutions in polar solvents, such as water, acetone, ethanol, and tetrahydrofuran, which disperse easily in polymers. The demonstrated C-N functionalization provides a new synthetic method and the NH₂-MWNTs can be used as precursors for the preparation of bismaleimide-MWNTs polymer materials.The bismaleimide (BMI)/MWNTs composites were prepared by in situ polymerization. The influence of MWNTs on the reaction activity of the BMI system was studied by DSC. The results showed that BMI with MWNTs fillers has extraordinary significance for the development of advanced materials with enhanced mechanical, thermal, electricical, frictional properties.