Efficient and Simple Surface Modification of Carbon Nanotubes by Dry Process Using hydrogen

Numerous studies have been conducted on the use of carbon nanotubes (CNTs) as reinforcement to improve polymer composites. However, limitations of carbon nanotubes such as their poor dispersity in the polymer matrix, poor alignment, and short aspect ratio hinder their practical use. Among there, the most important method to improve the mechanical properties of composites is by enhancing the interfacial bonding between carbon nanotubes and the matrix. Carbon nanotubes surfaces are inert; thus, they should be functionalized to generate active sites.

In previous studies, carbon nanotubes have been typically functionalized by harsh oxidative processes such as refluxing in mixtures of strong acid. However, the oxidation process usually introduces a large number of defects on the side walls and tips. Consequently, the mechanical properties of composite decreased. Another way is the non-covalent functionalization. It has attracted particular attention because it is an effective mode of carbon nanotube functionalization that does not generate any structural defects. But all these methods difficult to control maintain the alignment of the carbon nanotubes. In addition, another major problem is that both chemical and physical surface modifications generate some impurities on the carbon nanotubes surfaces, and such impurities are difficult to remove. Therefore, the development of a better and more effective functionalization method remains a major challenge.

We considered the hydrogenation process to make active site on carbon nanotubes surface because it is simple, easy handling and does not breakup alignment of carbon nanotubes. In general, the adsorption of hydrogen atoms and molecules on pristine carbon nanotubes has been studied for developing advanced nanoelectronic applications such as hydrogen storage and gas sensors.

In this study, we report a novel method to modify carbon nanotubes surfaces using hydrogen and develop a composite with epoxy resin. This method is effective in terms of functionalizing the carbon nanotube surface and improving the interaction between carbon nanotube and the epoxy polymer.