Effect of thermo-alkali treatment on the morphological and electrochemical properties of biopolymer electrolytes based on corn starch–Al(OH)3

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Abstract

A proton-conducting biopolymer electrolyte system based on corn starch doped with 0.0 to 4.0 wt% of Al(OH)3 has been prepared through the solution casting method. Scanning electron microscopy and confocal micrographs showed a partial alteration of starch granule boundary and aluminum agglomerates formation as a function of the Al(OH)3 concentration. X-ray diffraction and Fourier transform infrared spectra showed a decrease in the relative crystallinity and in the absorbance ratio 1047/1022, associated with the disruption of double-helix structures and the region of starch granule disorder, in concordance with the C1 and C4 deconvoluted curves obtained by CP/MAS 13C-NMR. Furthermore, corn starch films (CSF) mostly showed AlO5 (pentahedral) and AlO6 (octahedral) species as a function of the Al(OH)3 concentration, associated with a suitable Al3+ distribution through the CSF arrangement obtained by CP/MAS 27Al-NMR. Particularly, CSF with 2.0 wt% of Al(OH)3 showed 27.5 F g−1 of specific capacitance and 7.5 mS cm−1 of electrical conductivity values, using voltammetry cyclic and the van der Pauw four-point test, respectively. The electrochemical behaviour of CSF was occasioned by saturation limit of chemical bonds between the functional groups into the starch molecule and the Al3+ ions was achieved, this disarrange and/or bankrupt the sequence of CSF microstructure, caused by the coexistence of free Al3+ ions and aluminum agglomerates. All these results implied that the present proton-conducting biopolymer electrolyte system based on corn starch–Al(OH)3 has the potential to be applied in electrochemical devices.
Original languageSpanish (Mexico)
Article number1
Pages (from-to)1
Number of pages20
JournalPolymer Bulletin
Volume6
Issue number1
StatePublished - 3 Jun 2021

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