Effects of Different Concentration in (w/v)% of Carboxymethyl Iota-Carrageenan Based Green Polymer Electrolyte

Abstract

The effect of different concentrations in weight per volume percentage, (w/v)% of iota-carrageenan and carboxymethyl-iota carrageenan used as the green polymer electrolyte has been studied. The polymer electrolyte films were prepared by solution casting technique. Different concentration in the range from 1.0 – 6.0 (w/v)% were dissolved in fix volume of acetic acid which act as solvent. The films have been analyzed through attenuated Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) measurement and electrochemical impedance spectroscopy (EIS). The EIS results showed that the ionic conductivity increased as the concentration of the polymer increases. In comparison between iota-carrageenan and carboxymethyl iota-carrageenan, carboxymethyl-iota carrageenan showed better results due to the presence of more active site. The highest conductivity achieved by iota-carrageenan and carboxymethyl iota-carrageenan were 3.45 × 10-6S cm-1and 9.57 × 10-4S cm-1at the concentration 3.0 and 4.0 (w/v)% , respectively. From the FTIR spectra, it depicts that the intensity of significant peaks of ether and carboxylate group increases as the concentration of polymer increases. The XRD analysis showed that as the concentration of polymer increase, the amorphous region in the films would be enhanced. This study showed that the concentration play significant role in the ionic conductivity improvement.

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“…Carboxylation of κ-carrageenan provides more oxygen in the polymer, which facilitates the coordination bond formation with more cations compared to raw material and had been reported to increase the conductivity 227 times compared to pristine carrageenan. 261 Bella et al also reported two orders of magnitude greater conductivity in the case of carboxymethyl κ-carrageenan (CMKC) compared to pure carrageenan. 361 They had found the highest conductivity of 3.25 mS/cm for the electrolyte with 40% NaI and 30% EC.…”

“…For instance, carboxylation and methylation can enhance water solubility of the polymer, while phthaloylation is done to increase the organosolubility. 251,261,285,286,355 Similarly, cyanoethylation can make the polymer susceptible to less polar solvents. 256 Apart from the solubility, modification also influences the physical and electrical properties.…”

“…Modifications can be done by grafting, cross-linking, or replacing the hydrogen with desired functional groups as discussed earlier. These chemical modifications can make a polymer more conductive by increasing the polar sites to anchor ions, 146,251,256,310,316,410 water-soluble by carboxylation, 243,251,261,264,265,332 organosoluble by phthaloylation, 259,284,285,287 or it can lower T g and crystallinity of the polymer by adding bulky functional groups. 255,411,412 It is interesting to see that modifying properties can be tuned for any desire value by controlling the amount of modifying functional groups on the backbone.…”

“…efficiency of ι-carrageenan from 2.86 × 10 −7 to 2.21 × 10 −4 S/ cm by carboxylation 261. Subsequently, conductivity of carboxymethyl κ/ι-hybrid carrageenan was increased by adding salt and plasticizer (NH 4 I and glycerol) by Torres et al262 Increment in conductivity of this electrolytes due to incorporation of slats, ionic liquids, and plasticizers is related to the synergistic effect of incremental amorphous nature, segmental mobility, and reduction in secondary bonding forces of the polymer.…”