Estudo de eletrólitos poliméricos de blendas ágar-xantana e ágar-gelana: (síntese e caracterização)

Abstract

The polymeric electrolytes obtained from natural polymers has been widely used since the recent times due to their characteristics of biodegradation, as well as low cost of production and good physicochemical properties. This view shows the results of synthesis and characterization of new electrolytes of biopolymers based on agar, xanthan and gellan. Agar, xanthan blends with proton donors of acetic acid (CH3COOH), agar - xanthan blends with ions of lithium perchlorate (LiClO4) were prepared, agar - gellan blends were also prepared with proton donors CH3COOH - gellan and agar blends with ions of LiClO4. The blends were obtained in films and characterized using thermal analysis (TGA, DSC), structural analysis of x - ray diffraction (XRD), infrared spectroscopy (FT-IR), electrochemical impedance spectroscopy (EIS) and visualization of the surface of samples by electron microscopy (SEM). Studies have shown that with low crystallinity, with predominantly amorphous, transparent, with great flexibility, good uniformity and adhesion to glass, characteristic structures due to good plasticity displayed by biopolymers used. Obtained agar with xanthan blends with CH3COOH (Tg) ranging from -44.90 ° C to -80.13 ° C, these changes led to the increase of Tg of the amorphous state of the films also increased as the movement of polymer chains resulting directly increase the ionic conductivity as it appears in the Nyquist impedance diagrams , ranging from 1,3845X10-5 S.cm-1 a 7,8009X105S.cm-1 . The blends showed that the best ionic conductivities were gellan - agar blends with LiClO4 with Tg ranging from -26.26 ° C to -65.62 ° C; great plasticity of gellan coupled to lithium ions led to these blends a larger movement of the polymer chains resulting in higher values of ionic conductivity demonstrated by the Nyquist impedance diagrams with conductivity ranging from 3,8719X10-5S.cm-1 a 6,8329X10-5S.cm-1