Green polymer electrolyte host based on newly synthesized benzoyl k-carrageenan: less hydrophilic and improved conductivity

Newly synthesized benzoyl kappa carrageenan (Bz-kcar) has been successfully produced by Friedel Craft acylation method. The successful substitution of benzoyl molecule into kappa carrageenan (kcar) polymeric chain was confirmed by FTIR analysis based on the formation of new carbonyl (C=0) and C=C bonds in Bz-kcar. ^H-NMR analysis has further proven the benzoylation by the appearance of new multiple resonances peaks at 6 =6.6-9.50 ppm belongs to the characteristic signals of protons in aromatic benzoate group. XR D analysis showed reduced crystallinity of the synthesized carrageenan while elemental analyser analysis revealed the increase percentages of carbon in Bz-kcar upon the substitution. Highest degree of substitution obtained is 0.27. TGA showed lower degradation temperature in the synthesized carrageenan while water contact angle analysis demonstrated that Bz-kcar is less hydrophilic compared to the pristine kcar. Solubility tests showed that Bz-kcar is best dissolved in ethylene glycol. The benzoylation has also improved ionic conductivity of Bz-kcar to 3.10 x lO '' Scm"^ at ambient temperature.