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<p>Research on the study of dielectric and optical parameters of biopolymers doped with sodium salts is scarce in existing literature. In the current study, tamarind seed polysaccharide (TSP) was chosen as host biopolymer. Solution-casting technique was used for the preparation of TSP biopolymer electrolytes, which was doped with several varying concentrations of the chosen dopant salt sodium bromide (NaBr). Characterization techniques like XRD, SEM, DSC, AC impedance spectroscopy and UV–visible spectroscopy were deployed in order to make investigations on the structural, morphological, thermal, electrical and optical parameters. XRD analysis revealed that the crystallite sizes of the films of various composition decreased with a rise in the concentration of the dopant salt. SEM analysis revealed that smooth morphology was exhibited by the optimum composition TSP:NaBr (60:40&#xa0;wt%) film that confirmed its amorphous nature. DSC curves for the prepared films showed that a reduction in values of glass transition temperature (<i>T</i><sub>g</sub>) was observed with increase in the salt concentration, reaching the value of 49.18&#xa0;°C for the optimum concentration. The study of properties such as dielectric constant, electric modulus and loss tangent was studied using AC impedance spectroscopy. The results of AC impedance parameters showed that TSP:NaBr (60:40&#xa0;wt%) film had minimum values for tangent loss and electric modulus parameters, and maximum values for dielectric loss and dielectric constant, with increase in the frequency. The study of properties such as optical absorption, optical transmission, optical reflectance, optical refractive index, extinction coefficient, absorption coefficient, optical conductivity, optical dielectric loss, optical absorption band-gap, direct-allowed transitions energy band-gap, directly forbidden transitions energy band-gap, indirect-allowed transitions energy band-gap and Urbach energy was calculated. The study of optical properties like optical dielectric loss and band-gap for the prepared films showed that direct-allowed transitions were the predominant transitions. The energy of the optical band-gap for this transition had decreased from 4.87&#xa0;eV (for pure TSP) to 4.48&#xa0;eV for the composition TSP:NaBr (60:40&#xa0;wt%). Direct-allowed energy band-gap values, indirect-allowed energy band-gap values and absorption edge for pure TSP were high, and with a rise in the salt concentration, these gradually decreased. For the film TSP:NaBr (60:40&#xa0;wt%) concentration, energy band-gaps with lower values were obtained for direct and indirect transitions.</p>

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NaBr-doped tamarind seed polysaccharide (TSP) biopolymer electrolytes: exploring optical and dielectric frontiers for advanced applications

  • 期刊论文

  • 发表日期：

    2025年6月3日

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  • P. V. N. M. Kaushik,
  • N. Krishna Jyothi,
  • M. Gnana Kiran,
  • I. Siva Ramakoti

摘要

Research on the study of dielectric and optical parameters of biopolymers doped with sodium salts is scarce in existing literature. In the current study, tamarind seed polysaccharide (TSP) was chosen as host biopolymer. Solution-casting technique was used for the preparation of TSP biopolymer electrolytes, which was doped with several varying concentrations of the chosen dopant salt sodium bromide (NaBr). Characterization techniques like XRD, SEM, DSC, AC impedance spectroscopy and UV–visible spectroscopy were deployed in order to make investigations on the structural, morphological, thermal, electrical and optical parameters. XRD analysis revealed that the crystallite sizes of the films of various composition decreased with a rise in the concentration of the dopant salt. SEM analysis revealed that smooth morphology was exhibited by the optimum composition TSP:NaBr (60:40 wt%) film that confirmed its amorphous nature. DSC curves for the prepared films showed that a reduction in values of glass transition temperature (Tg) was observed with increase in the salt concentration, reaching the value of 49.18 °C for the optimum concentration. The study of properties such as dielectric constant, electric modulus and loss tangent was studied using AC impedance spectroscopy. The results of AC impedance parameters showed that TSP:NaBr (60:40 wt%) film had minimum values for tangent loss and electric modulus parameters, and maximum values for dielectric loss and dielectric constant, with increase in the frequency. The study of properties such as optical absorption, optical transmission, optical reflectance, optical refractive index, extinction coefficient, absorption coefficient, optical conductivity, optical dielectric loss, optical absorption band-gap, direct-allowed transitions energy band-gap, directly forbidden transitions energy band-gap, indirect-allowed transitions energy band-gap and Urbach energy was calculated. The study of optical properties like optical dielectric loss and band-gap for the prepared films showed that direct-allowed transitions were the predominant transitions. The energy of the optical band-gap for this transition had decreased from 4.87 eV (for pure TSP) to 4.48 eV for the composition TSP:NaBr (60:40 wt%). Direct-allowed energy band-gap values, indirect-allowed energy band-gap values and absorption edge for pure TSP were high, and with a rise in the salt concentration, these gradually decreased. For the film TSP:NaBr (60:40 wt%) concentration, energy band-gaps with lower values were obtained for direct and indirect transitions.