Chemical interaction and conductivity of carboxymethyl κ-carrageenan based green polymer electrolyte

The potential of kappa-carrageenan derivatives as a green polymer electrolyte has been explored. kappa-Carrageenan extracted from marine red algae was reacted with monochloacetic add to form carboxymethyl kappa-carrageenan. The powders were characterized by reflection fourier transform infrared (ATR-FTIR) spectroscopy, C-13 nuclear magnetic resonance, H-1 nuclear magnetic resonance, X-ray diffraction and elemental analysis to confirm the structural, crystallinity and the degrees of substitution. A green polymer electrolyte of kappa-carrageenan and carboxymethyl kappa-carrageenan were prepared by solution-casting technique. The films were characterized by reflection fourier transform infrared (ATR-FTIR) spectroscopy and electrochemical impedance spectroscopy to determine the chemical interaction and ionic conductivity. The decrease in intensity of hydroxyl, carbonyl, sulfate and ether band confirmed the polymer solvent complex formation. XRD spectra show that chemical modification of kappa-carrageenan does not change its amorphous properties. The ionic conductivity was found to increase by three magnitudes higher with the chemical modification of kappa-carrageenan. The conductivity achieved was 2.0 x 10(-4) S cm(-1) for carboxymethyl kappa-carrageenan in comparison to 5.3 x 10(-7) S cm(-1) for kappa-carrageenan. (C) 2012 Elsevier B.V. All rights reserved.