Writers: M. Piacenti-Silva, E.S. Bronze-Uhle, J.V. Paulin, C.F.O. Graeff
Keywords: Melanin Dimethyl sulfoxide Synthesis Temperature Optimization Photoabsorption
Abstract: Melanins are a class of pigmentary conjugated macromolecules found in many biological systems. Functionalization of synthetic melanin provides interesting new properties like the greater solubility of melanin synthesized in dimethyl sulfoxide, d-Melanin. In this work we have studied the influence of temperature on d-Melanin synthesis and its properties. To this end, UV–Vis, Fourier-transform infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) techniques have been employed to analyze d-Melanin synthesized within the range of 25–100 °C. Our results reveal that by increasing the synthesis temperature up to 100 °C, the synthesis time can be decreased by a factor of 7 when compared to room temperature. From FTIR and 13C CP/MAS NMR analyses the increase in temperature causes a decrease in the number of carbonyl groups from carboxylic acid and from ionized carboxylic acid. The decarboxylation of d-Melanin monomers at higher temperatures shows that the use of higher synthesis temperatures influences the elimination of carbonyls present in the precursor molecules, thus facilitating the polymerization of d-Melanin.
Writers: Marcela F. Silva, Mariani A. Ciciliatti, Ana A. W. Hechenleitner, Rebeca Peñalva, Maite Agüeros, Juan M. Irache, Adilson J. A. de Oliveira, Ammad A. Farooqi, Edgardo A. G. Pineda Keywords: maghemite; nanocapsules; optimization; poly (ɛ- caprolactone); […]
Writers: C. Aliotta and L.F. Liotta and V. La Parola and A. Martorana and E.N.S Muccillo and R. Muccillo and F. Deganello Keywords: Samarium doped ceria; IT-SOFC; Solution combustion synthesis; Sintering in reducing atmosphere; Reducibility Abstract: Ce0.8Sm0.2O2 − x powders […]
Thermal and electrical properties of CaCu3Ti4O12 synthesized by soft chemistry route Abstract: Calcium copper titanate powders were synthesized by a soft chemistry route, aiming to establish a cost-effective solution method to obtain sintered ceramics with giant […]