In this work, we report for the first time, the synthesis of several carbon nanotube (CNT)/polyaniline (PANI) nanocomposites obtained through interfacial polymerization, in which the resulting material is obtained directly as a transparent and freestanding film at the water−toluene interface. The films are obtained spontaneously with high stability and can be easily transferred with high optical quality to any kind of substrate or directly to a desirable device. Samples containing several CNT/PANI ratios have been prepared. The characterization of the resulting materials was carried out by FT-IR, UV−vis-NIR, and Raman spectroscopy, X-ray diffraction, cyclic voltammetry, scanning and transmission electron microscopy, and conductivity measurements. The results indicate that the polymerization of aniline starts at the carbon nanotube walls, resulting in polymer-coated CNTs. A π−π interaction between the CNTs and the PANI is proposed. The formation of the self-standing films is discussed in terms of the stabilization of the water−toluene interface.

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This communication reports a simple, one-pot procedure for the synthesis and processing of transparent and conductive thin films of graphene/polyaniline nanocomposites based on an interfacial polymerization. Thin films presenting transmittance of 89% and sheet resistance of 60.6 Ω sq(-1) are spontaneously obtained and can be easily transferred to suitable substrates.

Recebido em 16/7/13; aceito em 1/10/13; publicado na web em 24/10/13 CARBON NANOSTRUCTURES (NANOTUBES AND GRAPHENE): QUO VADIS? We describe general considerations about the present and the future standing of carbon nanostructures, mainly carbon nanotubes and graphene. Basic concepts and definitions, select structure/property relationships, and potential applications are reviewed. The analysis of the global market for these nanostructures, the commercial products available currently, the role of the chemistry, the main challenges remaining and a brief view of the field in Brazil are also presented and discussed.Keywords: carbon nanotubes; graphene; nanoscience and nanotechnology. INTRODUÇÃOA última década do século XX foi marcada pela consolidação e crescimento vertiginoso de uma nova área do conhecimento, que trouxe no seu bojo a promessa de uma verdadeira revolução científica e tecnológica, derrubando antigos paradigmas, abrindo novos horizontes e rompendo fronteiras estabelecidas entre disciplinas: a nanociência e nanotecnologia (N&N). De maneira bastante simplificada, o princípio básico que suporta a N&N se baseia no fato de que propriedades da matéria dependem não só da sua composição e estrutura, como também de seu tamanho e formato. Abaixo de um determinado tamanho crítico, sempre na ordem de alguns nanômetros (daí o termo nanociência e nanotecnologia -a ciência e tecnologia da matéria em escala nanométrica), as propriedades de um determinado material se tornam diferenciadas daquelas observadas para o mesmo material em escala macroscópica. Desta forma, novos materiais, com propriedades diferenciadas, passaram a ser preparados somente pelo controle de tamanho e forma de materiais já conhecidos, ampliando significativamente o leque de oportunidades. 1 A N&N se caracteriza por uma alta multi-e interdisciplinaridade, na qual diferentes especialidades naturalmente passaram a sinergicamente compartilhar suas expertises: químicos, físicos, engenheiros, biólogos, matemáticos, médicos, ambientalistas, advogados, dentre outros, possibilitaram a compreensão de fenômenos e a geração de produtos com aplicações em potencial em todos os ramos da atividade humana: energia, agricultura, meio ambiente, bens de consumo, saúde e medicina, manufatura, construção civil, transporte, eletrônica, tecnologia da informação, cosméticos, têxteis, entretenimento, comunicação, lazer, etc.Dentre todos os novos(?) materiais oriundos da N&N, talvez os mais sintomáticos são os conhecidos genericamente como nanomateriais de carbono, dos quais os nanotubos de carbono (NTC), e mais recentemente o grafeno, são os mais representativos. Não deixa de ser fascinante a constatação de que o elemento químico símbolo da vida e massivamente associado à ciência química seja o único constituinte de alguns dos materiais mais intrigantes conhecidos. A riqueza e diversidade do elemento carbono, tão familiar aos químicos orgânicos, se manifesta também na química de materiais e na N&N.A Figura 1 apresenta algumas estruturas alótropas do carbono atualmente conh...

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This paper focuses on the preparation and characterization of a titanium-tin mixed oxide (Ti,Sn)O 2 with anatase structure. The preparation method is based on a sol-gel technique using titanium tetra-isopropoxide and tin tetrachloride as precursors. The obtained TiO 2 and titanium-tin mixed oxide xerogels and their heat-treated products were characterized by thermal analysis, X-ray diffractometry, Raman spectroscopy, and X-ray absorption spectroscopy. The results indicate that the (Ti,Sn)O 2 was obtained in the nanometer scale and the crystallite size was smaller than the pure TiO 2 obtained by a similar route. The mixed oxide was obtained as a solid solution. Compared to the bulk TiO 2 , the Raman spectra of both TiO 2 and (Ti,Sn)O 2 xerogels present an excessive E g peak broadening, which was attributed to the presence of surface low-coordinated titanium atoms. The occurrence of these species was confirmed by XANES and EXAFS spectra of both pure TiO 2 and (Ti,Sn)O 2 xerogels.

Dodecanethiol-stabilized platinum nanoparticles of less than 3 nm have been synthesized for the first time through a modified two-phase liquid-liquid route. The H 2 PtCl 6 precursor was transferred from water to toluene using tetra-n-octylammonium bromide, followed by the addition of dodecanethiol. Results obtained by Raman spectroscopy, X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) indicate a reaction between the platinum precursor and the thiol, resulting in a Pt(II)-stable complex that cannot be reduced by sodium borohydride. The Pt nanoparticles were obtained by the reduction of the platinum precursor before the introduction of dodecanethiol. The time interval at which the dodecanethiol was added to the reaction was used to control the size of the nanoparticles. The formation of dodecanethiol-stabilized Pt nanoparticles with fcc structure and average diameter of 1.7, 2.2 and 2.4 nm was confirmed by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), XANES, and EXAFS. All of the obtained nanoparticles were electrocatalytically active for methanol oxidation, and the differences in catalytic activity between different samples were related to the size and morphology of the nanoparticles.