Preparação e caracterização de eletrólitos sólidos poliméricos à base de goma xantana

Abstract

This research proposes the study and characterization of a new solid polymeric electrolytes xanthan gum based for use in electrochromic devices. Xanthan gum is a polysaccharide known for its use in various industries, recommending the food industry; the solution formed from the xanthan gum is transparent with high viscosity and stability, even in different conditions of the environment, for example pH and temperature. For the formation of polymer films, in addition to the xanthan gum, ethylene glycol was used as plasticizer and glutaraldehyde as crosslinking agent. To promote the ionic conduction, acetic acid was used as a source of protons. Electrolytes were first characterized by electrochemical impedance spectroscopy (EIS) to determine the ionic conductivity versus concentration (acid protons) and a function of temperature. X-ray diffraction was performed to determine if the electrolyte had an amorphous or crystalline character. In addition, a thermal analysis was conducted (DSC and TGA) to determine the glass transition temperature (Tg) and thermal degradation of the electrolyte. Spectrophotometric measurements (UV-Vis) were performed to determine the transparency of electrolytes. The morphology and roughness were studied by analysis of the surface of the electrolyte by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The best results were presented by electrolyte with the addition of 50% acetic acid by weight, obtaining an ionic conductivity at room temperature of 7,93×10-5 S/cm and with the increase in temperature to 80 ºC, the conductivity was 3,06×10-4 S/cm. The electrolyte presented a predominantly amorphous character and the transmittance in the visible region was 80%. The glass transition temperature was -87 ºC and the degradation temperature was 134 ºC. Through the micrographs surface of the electrolyte, the absence of cracks were observed, resulting in a homogeneous surface. The ionic conduction mechanism presented by the electrolyte was the type Arrhenius. The results shown that solid polymeric electrolytes based on xanthan gum are promising for application in electrochromic devices