Single-walled carbon nanotube networks in conductive composite materials.

Oana A Bârsan,Leo G J Van Der Ven,G (Bert) De With,Günter G Hoffmann

doi:10.1039/c4fd00087k

Abstract

Electrically conductive composite materials can be used for a wide range of applications because they combine the advantages of a specific polymeric material (e.g., thermal and mechanical properties) with the electrical properties of conductive filler particles. However, the overall electrical behaviour of these composite materials is usually much below the potential of the conductive fillers, mainly because by mixing two different components, new interfaces and interphases are created, changing the properties and behaviours of both. Our goal is to characterize and understand the nature and influence of these interfaces on the electrical properties of composite materials. We have improved a technique based on the use of sodium carboxymethyl cellulose (CMC) to disperse single-walled carbon nanotubes (SWCNTs) in water, followed by coating glass substrates, and drying and removing the CMC with a nitric acid treatment. We used electron microscopy and atomic force microscopy techniques to characterize the SWCNT films, and developed an in situ resistance measurement technique to analyse the influence of both the individual components and the mixture of an epoxy/amine system on the electrical behaviour of the SWCNTs. The results showed that impregnating a SWCNT network with a polymer is not the only factor that affects the film resistance; air exposure, temperature, physical and chemical properties of the individual polymer components, and also the formation of a polymeric network, can all have an influence on the macroscopic electrical properties of the initial SWCNT network. These results emphasize the importance of understanding the effects that each of the components can have on each other before trying to prepare an efficient polymer composite material.

Highlights

The potential of carbon nanotubes (CNTs) in many different elds has led to an exponential growth of interest in these materials over the past twenty years.[1]
In the rst part of our research, Single-walled carbon nanotubes (SWCNTs) lms were prepared using a technique adapted from Li et al.,[24] from a water solution of SWCNTs dispersed with carboxymethyl cellulose (CMC)
The prepared lms were characterized by Scanning electron microscopy (SEM) and TEM a er each step of the process to ensure the complete removal of CMC residues, and the nanometer and micrometer scale homogeneity of the SWCNT lms

Summary

Introduction

The potential of carbon nanotubes (CNTs) in many different elds has led to an exponential growth of interest in these materials over the past twenty years.[1]. Because SWCNTs exert strong van der Waals attractive forces, they are very difficult to disperse without the use of surfactants or other dispersion agents.[13,14,15,16] Functionalization has proved to be efficient in increasing SWCNT dispersibility in different solvents or polymers.[17,18] the process involves damaging the surface of the SWCNTs, which in turn affects their mechanical and electrical properties Despite their potential and the numerous studies on SWCNTs, there are many unresolved issues when practical applications, such as electrically conductive composites, are concerned. These materials have not yet surpassed the efficiency of existing composite materials such as graphite or metal ber/ ake reinforced polymers.[19,20]

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Results

Conclusion