Organic/inorganic hybrid materials formed from TiO2 nanoparticles and polyaniline

Abstract

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...

Electrochemical synthesis and characterization of TiO2-polyaniline composite layers

“…For this particular specimen an average thickness of 33 lm corresponded to a redox charge of 350 mC cm -2 and a very high surface roughness (morphology features with height between 25 and 50 lm) was observed. On the other hand SEM on TiO 2 -PANI-coated graphite substrates with composite layers produced through a few (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) potentiodynamic scans showed incomplete coverage of the underlying substrate by the polymer layer. For this reason in the text we have always specified the redox charge of the deposited composites instead of the polymer layer thickness.…”

“…Various attempts have been made to incorporate TiO 2 nanoparticles in conducting polymer materials with the aim of obtaining composites with high conductivity [1], high piezoresistivity [2], high photoconductivity [3], improved battery storage characteristics [4] and corrosion protection properties [5] or for light image formation [6]. Most of the work in the field [1][2][3][7][8][9][10][11] was performed by using chemical approaches for the synthesis of composite polyaniline (PANI) and polythiophene-based materials. Electrochemical synthesis has been used in a few studies, i.e., in the case of TiO 2 /PANI [1,6,12] and TiO 2 /polypyrrole [5,13,14].…”

A Polianilina No Cenário Ambiental: Uma Aborgagem Sobre Fotocatálise Heterogênea

“…O espectro UV-Vis do sal esmeraldina apresenta três bandas características: duas bandas em aproximadamente ~ 320 -380 nm e ~ 415 -450 nm referentes as transições π -π * e pôlaron -π * , respectivamente, e uma terceira banda larga situada na faixa do visível entre ~ 700 à 850 nm indicando a transição π -pôlaron. 15,40,41,[44][45][46] Portanto, num catalisador compósito, o sinergismo entre a polianilina e o óxido metálico potencializa a oxidação de contaminantes sob radiação solar, aproveitando grande parte da energia incidente que corresponde à faixa do visível. A influência dessa propriedade na fotocatálise está associada às junções n-p formadas entre óxidos metálicos e polianilina, descritos como semicondutores tipo n e p, respectivamente.…”

Synthesis of Polypyrrole-Intercalated Grafted Zirconium Phosphate Films by Anodic Electrodeposition and Their Electrochemical Capacities

“…In order to accelerate or improve their properties, inorganic-conductive polymer hybrids, which are nanoparticle-dispersed structures and/or conductive polymer-intercalated layered compounds, were examined as follows. Schnitzler, et al reported preparation of a TiO 2 nanoparticle/polyaniline hybrid [6]. Manganese oxide/polypyrrole nanocomposites were studied by Sharma et al [7].…”