Papers by Raquel Vichessi
Polímeros, 2008
Este trabalho descreve um estudo sobre o efeito do envelhecimento sob radiação UV no transporte d... more Este trabalho descreve um estudo sobre o efeito do envelhecimento sob radiação UV no transporte de água em filmes planos de PET reciclados de garrafas de bebidas carbonatadas. A partir do formalismo termodinâmico utilizando a relação de Eyring e os resultados de coeficientes de permeabilidade, foram determinadas a entropia e a entalpia de ativação para o transporte da água. Estas funções representadas num gráfico de efeito de compensação termodinâmica permitiram correlacionar a degradação do material, avaliada via espectroscopia na região do infravermelho com transformada de Fourier, com o transporte de água. Foram analisados os possíveis efeitos da presença de estabilizantes, pigmentos e história de processamento.
High performance electrochromic electrodes prepared by the electrophoretic deposition of Au@PEDOT... more High performance electrochromic electrodes prepared by the electrophoretic deposition of Au@PEDOT (gold@poly (3,4-ethylenedioxythiophene)) nanoparticles were characterized. A detailed study was performed using scanning transmission electron microscopy (STEM) combined with a chemical analysis at the nanometer level showing core-shell structures with sizes ranging from 2 to 8 nm. X-ray diffraction and Raman experiments were also performed. The modified electrodes present homogeneous surfaces with increased roughness, leading to excellent electrochromic properties like a high chromatic contrast with an electrochromic efficiency of ca. 300 C À 1 cm 2 with a response time of approximately 60-70 ms for 90% of coloration. The fast switching was related to the location of the solid state electrochromic reaction, the very thin PEDOT layer surrounding the Au core of the nanoparticles.
Vibrational Spectroscopy, 2013
We describe the preparation of Prussian Blue films with several thicknesses, and their characteri... more We describe the preparation of Prussian Blue films with several thicknesses, and their characterization by means of cyclic voltammetry and polarized reflection FTIR spectroscopy. The electrochemical experiments demonstrated a direct relationship between the film thickness and its intrinsic conductivity. The vibrational spectra showed asymmetrical bands in the vicinity of the cyanide stretching band. The s-polarization bands showed a shift to higher frequencies, while the p-polarization bands showed a downshift with increasing film thickness. The presence of shifted cyanide stretching bands in the s-and p-polarizations is attributed to the columnar shape of Prussian Blue grains formed in the growth process.
Química Nova, 2014
describing the basic aspects and methodologies employed for the construction and analyses of diff... more describing the basic aspects and methodologies employed for the construction and analyses of different modified electrodes. The work presents the classic materials used for the construction of electrochromic electrodes, such as WO 3 and a view on the basic concepts of chromaticity as a useful approach for analyzing colorimetric results. The report also addresses how the incorporation of nanomaterials and the consequent novel modification of electrodes have furthered this area of science, producing electrochromic electrodes with high performance, high efficiency and low response times.
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Papers by Raquel Vichessi