This work describes the preparation, characterization and properties study of multifunctional nanocomposites between poly(styrene-co -butyl acrylate) latex and different carbon nanostructures: iron-filled carbon nanotubes (CNT), graphene or graphene oxide. Different approaches were employed to prepare stable aqueous dispersions of these nanostructures, according to the specificity of each nanomaterial. The nanocomposites were characterized by Raman and Fourier transform infrared (FTIR) spectroscopy, as well as by scanning probe microscopy (SPM) at different modes, providing information regarding the nature of the interaction between the carbon nanostructures and the polymeric matrix. The synergistic effect between the components results in improved mechanical, electrical, thermal and chemical properties of the nanocomposites, when compared to the neat polymer. In addition, the iron species into CNT cavities provide an interesting and unusual magnetic property of the nanocomposites. Results show that the properties of the nanocomposites can be modulated aiming desired application by simply selecting the amount and/or the kind of carbon nanostructure. This work provides information on the features of the three systems used, showing the range of properties that can be covered by using the three nano-fillers.

This work shows the influence of several reactional parameters for obtaining graphene through successive steps of oxidation and exfoliation of bulk graphite (resulting in graphene oxide), followed by chemical reduction. The results showed that changes in temperature, reaction time, reducing agent and source of primary graphite lead to different surface compositions and stability in dispersion of graphene oxide. Also, the use of different reducing agents promoted different degrees of restoration of C=C bonds in the bidimensional structure of graphene.

O efeito de cinco diferentes tratamentos químicos (HNO3, H2SO4, H2O2, HNO3 + H2SO4 e HNO3 + HCl) na homogeneidade, superfície, estrutura e dispersabilidade em água de nanotubos de carbono do tipo multi-paredes preenchidos com ferro ou óxido de ferro foi estudado através de difratometria de raios X (XRD), espectroscopias Raman, UV-Visível e fotoeletrônica de raios X (XPS), análise termogravimétrica (TG) e microscopia eletrônica de varredura (MEV). Os resultados indicaram que os tratamentos são efetivos na remoção de espécies carbonáceas diferentes de nanotubos, presentes na amostra. Com exceção do tratamento com H2O2, uma boa remoção das espécies contendo metal também foi observada. Além de aumentar a homogeneidade das amostras, os tratamentos também criam grupos carboxílicos e hidroxílicos superficiais, que afetam diretamente a dispersabilidade destas espécies em água. Dispersões estáveis de 2,24 × 10-1 g L-1 de nanotubos em água foram obtidas após o tratamento com mistura de ácido sulfúrico e ácido nítrico.

The effect of five different chemical treatments (HNO3, H2SO4, H2O2, HNO3 + H2SO4 and HNO3 + HCl) on the homogeneity, surface chemistry, structure and dispersibility in water of iron- and iron oxide-filled multi-walled carbon nanotube samples was evaluated by X-ray diffractometry (XRD), Raman, UV-Visible and X-ray photoelectron (XPS) spectroscopies, thermogravimetric analysis (TG) and scanning electron microscopy (SEM). The results indicate that the chemical treatments are generally effective in removing non-nanotube carbonaceous species present in the sample. With the exception of the H2O2 treatment, the chemical treatments also offer good removal of free iron-species. Besides the increase in the sample homogeneity, the chemical treatments promoted an increase in the carboxyl and hydroxyl groups at the carbon nanotube surface, what directly affects the dispersibility of these carbon nanotubes in water. Dispersions of 2.24 × 10-1 g L-1 were obtained for the treated samples with a mixture of nitric and sulfuric acid.