This paper describes the synthesis and characterization of new organic/inorganic hybrid materials formed from the mixed oxide (Ti,Sn)O 2 nanoparticles and polyaniline (PANI). The preparation method is based on a sol-gel technique using titanium tetra-isopropoxide and tin tetrachloride as oxide precursors, and two synthetic routes to the hybrids formation were employed, based on the addition of aniline after or before the sol formation. Different amounts of aniline were used to verify this effect on the characteristics of the formed materials. Samples were characterized by thermal analysis, X-ray diffractometry, Raman, UV-vis, and FT-IR spectroscopy, transmission electron microscopy, cyclic voltammetry, and conductivity measurements. Results show that the different experimental routes are successful in producing hybrids formed by oxide nanoparticles or nanotubes and polyaniline in its conducting form, the emeraldine salt. There is little difference between the samples obtained by the two synthetic routes employed, except by the amount of polymer in the final material. The hybrids that contain approximately 10% weight of polyaniline are formed as a core/ shell mixed oxide/polyaniline material.

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.

Este artigo descreve a síntese e caracterização de diferentes híbridos orgânico/inorgânicos formados entre a polianilina e o óxido de titânio. O método de preparação é baseado no processo sol-gel, partindo do isopropóxido de titânio como precursor. Duas rotas sintéticas visando a obtenção dos híbridos foram utilizadas, baseadas na mistura da anilina no meio reacional antes ou após a formação do óxido. Diferentes quantidades de anilina foram utilizadas visando compreender este efeito nas características do material final formado. As amostras foram caracterizadas por análise térmica, difratometria de raios-X, espectroscopias Raman, UV-Vis em modo refletância difusa e IV-TF, além de voltametria cíclica. Os resultados indicaram que os diferentes procedimentos experimentais foram bem sucedidos na obtenção de híbridos formados por nanopartículas de TiO 2 (estrutura anatase) e polianilina em sua forma condutora, sal esmeraldina. Não foram detectadas grandes diferenças entre as amostras obtidas através das duas rotas sintéticas utilizadas, exceto pela quantidade de polímero formada nos materiais. This paper describes the synthesis and characterization of organic/inorganic hybrid materials formed from TiO 2 nanoparticles and polyaniline (PANI). The preparation method is based on a solgel technique using titanium tetra-isopropoxide as oxide precursor, and two synthetic routes to the hybrids formation were employed, based on the addition of aniline after or before the sol formation. Different amounts of aniline were used to verify this effect on the characteristics of the formed materials. Samples were characterized by electronic spectroscopy, Raman spectroscopy, Fourier transformed infrared spectroscopy, thermal analysis, X-ray diffractometry and cyclic voltammetry. Results show that the different experimental routes are successful to produce hybrids formed by oxides nanoparticles and polyaniline in its conducting form, the emeraldine salt. There are no strong differences between the samples obtained by the two synthetic routes employed, except by the amount of polymer in the final material. Keywords: sol-gel method, polyaniline, nanocomposites IntroductionInterest in the development of new inorganic/organic (nano)composites has grown in recent years due to a wide range of potential use of these materials.1-10 These hybrids constitute a class of advanced composite materials with unusual properties, which can be used in many fields such as optics, ionics, electronics, mechanics etc.One important class of hybrid materials is that in which the organic fraction is composed by conducting polymers, such as polyaniline (PANI) or polypyrrole. [11][12][13][14][15][16][17][18][19] The unique properties of hybrid materials become more pronounced when at least one of the fractions occurs in nanometric scale. Nanocomposites in which the polymer fraction occurs in nanometric scale can be obtained by the encapsulation of conducting polymers within void spaces of inorganic host matrices such as pores, cavities, tunnels, micelles and inte...

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