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da Silva J.R.T.,Laboratorio Interdisciplinar Of Materiais Avancados Limav | Filho E.C.S.,Laboratorio Interdisciplinar Of Materiais Avancados Limav | Eiras C.,Laboratorio Interdisciplinar Of Materiais Avancados Limav
Colloid and Polymer Science | Year: 2015

In this study, a new material, i.e., composite PANI(MAC) based on polyaniline (PANI) and microcrystalline cellulose modified with maleic anhydride (MAC), was generated in the form of thin films immobilized on indium tin oxide (ITO) slides using a layer-by-layer self-assembly technique. For comparison, thin films of PANI in the absence of MAC were also prepared under the same conditions as those for PANI(MAC). Characterization of PANI(MAC) by ultraviolet-visible (UV-vis) spectroscopy showed that MAC acts as an organic acid that promotes secondary doping of PANI, as evidenced by the appearance of an absorption broadband at 900 nm. Cyclic voltammetry (CV) measurements revealed this same effect: the current density values obtained for the PANI(MAC) film were higher than those obtained for PANI in the absence of MAC. Studies on the behavior of the PANI and PANI(MAC) films at different pH values revealed that the PANI(MAC) films required a higher pH to generate electroactivity, which was not required for the reference films. Stability testing of the PANI(MAC) films revealed that their electrochemical profiles did not change after 3 months; this indicates that the presence of cellulose in the film did not accelerate degradation of the polyaniline. © 2014, Springer-Verlag Berlin Heidelberg.

Teixeira P.R.S.,Laboratorio Interdisciplinar Of Materiais Avancados Limav | Teixeira P.R.S.,Instituto Federal Of Educacao Ciencia E Tecnologia Do Piaui Ifpi | do Nascimento Marreiro A.S.,Instituto Federal Of Educacao Ciencia E Tecnologia Do Piaui Ifpi | Farias E.A.O.,Nucleo de Pesquisa em Biodiversidade e Biotecnologia | And 3 more authors.
Journal of Solid State Electrochemistry | Year: 2015

Hybrid and electroactive thin films containing microcrystalline cellulose (MC) or MC modified with a phosphate group (PC) were prepared in conjunction with polyaniline (PANI) and poly(vinyl sulfonic acid) (PVS) by the layer-by-layer technique. The MC or PC was dispersed in a PANI solution employed in the deposition process, and they produced the PVS/PANI(MC) and PVS/PANI(PC) films. The ultraviolet-visible (UV-Vis) studies showed that the same amount of material was adsorbed at each stage of deposition, characterizing the PVS/PANI(MC) and PVS/PANI(PC) films as self-regulated systems. The electrochemical measurements and cyclic voltammetry were carried out in a buffered medium and showed that PVS/PANI(PC) films present higher values of current density probably due to the self-doping process of polyaniline in the presence of phosphate cellulose. The PVS/PANI(PC) film was tested in the presence of chromium VI, and in this case, the presence of a third reduction peak at 0.38 V was observed, which is characteristic of this metal, demonstrating the possibility of PVS/PANI(PC) as an active layer in the development of sensors for monitoring groundwater springs. © 2015, Springer-Verlag Berlin Heidelberg.

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