Covalent attachment of functionalized polyaniline nanofibers onto graphene oxide

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valent attachment of cysteamine-functionalized polyaniline (PANI–NH2) nanofibers onto graphene oxide (GO) sheets in an aqueous medium is investigated for the first time. The functionalized PANI is covalently attached onto the GO surface by simple amidation in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. The technique can be conveniently scaled up for bulk production. The hybrid nanomaterial is easily synthesized, has good thermal stability, and disperses well in a solvent. Characterization techniques (Fourier transform infrared spectroscopy, thermogravimetry analysis, field emission scanning electron microscopy, and transmission electron microscopy) indicate the successful binding of the functionalized PANI nanofibers onto GO.

I. INTRODUCTION

Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2012.284

Indeed, various carbon materials have been used in preparing composite materials.11,12 GO has been demonstrated to be a good filler for polymer nanocomposites.13 When the advantages of carbon materials are combined with those of PANI, the resulting composites acquire synergistic features.11,14 Well-known processes for the preparation of noncovalent conjugate PANI–GO composites include mixing of preformed PANI with GO15 and in situ chemical polymerization of aniline monomer in solution in the presence of GO.16 However, using noncovalent bonding as the immobilization method has the disadvantage of PANI being easily desorbed from the surface of GO during use because no strong interfacial bonding exists between GO and PANI. Graphene is also substantially hindered in the stiffening or strengthening of the composite through traditional shear lag-based mechanisms, which result in nanostructured holes or matrix flaws. These phenomena significantly affect the manufacture of high-performance graphene-reinforced composites. Conversely, the covalent attachment of PANI onto GO ensures the sufficiency of immobilization of PANI without leaching from the substrate surface during use.17 In this study, we report an easy approach for immobilizing PANI onto GO sheets. PANI nanofibres are functionalized with cysteamine, which contains the amine functional group (–NH2). The amine group has high reactivity that enables it to react easily with many other chemicals. On the other hand, the large amount of oxygenous groups on the GO sheets enables easy interaction with the amine groups of PANI–NH2 through covalent bonds. The PANI–GO conjugate is inexpensive and easily scalable. The nanocomposite is easily synthesized at room temperature in an aqueous medium, and can be dispersed

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Ó Materials Research Society 2012

Graphene, a single layer of carbon atoms, has potential use in next generation nanodevices because of its unique electrical, optical, catalytic, and mechanical properties.1 However, due to the special two-dimensional structure, high surface energy, and intrinsic van der Waals forces of pure graphene, it tends to aggregate and entangle spontaneously, thereby limiting its technologi