Síntese e Caracterização de Eletrólitos Sólidos Poliméricos à Base de Álcool Polivinílico - (PVA) e Goma Xantana

Abstract

This research was conducted to study and characterization of new solid polymeric electrolytes based on PVA and xanthan gum, for use in flexible electrochromic devices. Polyvinyl alcohol (PVA) is a synthetic polymer which is prepared by polymerizing vinyl acetate, transparent, colorless and soluble in water. Along with the PVA used is a natural polymer which is obtained by Xanthomonas bacteria which infects the plant, and produces a high molecular weight polysaccharide known as Xanthan gum, which is widely used additive in pharmaceutical and food as a stabilizer, thickener and emulsifier. In addition, it is also used for the formation of polymeric films, glycerol as plasticizer and formaldehyde as a crosslinker. As a source of protons to promote ionic conduction, acetic acid was used. Electrolytes have been characterized by electrochemical impedance spectroscopy (EIS) to determine the ionic conductivity as a function of the concentration of mobile species (acid proton) and depending on the temperature. The X-ray diffraction was performed at room temperature to determine if the electrolyte had an amorphous or crystalline character. Spectrophotometric measurements were performed (UV-Vis) to determine the transparency of electrolytes and absorption of light. To study the roughness was carried out the analysis of atomic force microscopy (AFM). It was also conducted, testing for mechanical properties to verify the resistivity of the film. The best results with regard to ion conductivity for the electrolyte based on xanthan gum and PVA base with the addition of 50% and 27% acetic acid at room temperature were respectively 7.93 × 10 -5 S/cm and 1.19 × 10 -5 S / cm, while the electrolyte xanthan PVA gum base with the addition of acetic acid 55% by mass got value of 19.7 × 10 -5 S/cm and increasing the temperature at 80 ° C, the conductivity was 74,1 × 10 -5 S/cm. From the log of the conductivity, there was an Arrenhius behavior in the chain and a low activation energy. This same electrolyte, presented a predominantly amorphous character, with transmittance in the visible region of 80% and good absorbance. In AFM roughness observed for PVA-based electrolyte, PVA xanthan gum and xanthan gum were 52.2 nm, 18.4 nm and 31.7 nm, respectively. Finally, the tensile test, no breaking of PVA films PVA and xanthan gum with a maximum force of 18N applied, obtaining the following strain values of 1372.45 and 2322.35 0 and modulus of elasticity , 0009 MPa to 0.0002 MPa. The results show that the solid polymeric electrolytes PVA xanthan-gum base are promising for application to flexible electrochromic devices.