Solid polymer electrolytes based on chitosan NaCF3SO3 have been prepared by the solution cast technique. X-ray diffraction shows that the crystalline phase of the pure chitosan membrane has been partially disrupted. The fourier transform infrared (FTIR) results reveal the complexation between the chitosan polymer and the sodium triflate (NaTf) salt. The dielectric constant and DC conductivity follow the same trend with NaTf salt concentration. The increase in dielectric constant at different temperatures indicates an increase in DC conductivity. The ion conduction mechanism follows the Arrhenius behavior. The dependence of DC conductivity on both temperature and dielectric constant ( ) is also demonstrated. 1. Introduction Ion conducting polymers are an active area of study in materials research. They are prepared by complexing polymers containing polar groups with alkali metal salts [1]. Being light weight and flexible [2, 3], attempts have been made to use solid polymer electrolytes in solid-state electrochemical devices such as batteries, fuel cells, electrochromic displays, and smart windows [4]. Polymer electrolytes usually contain both crystalline and amorphous phases. It has been reported that the ion conduction takes place primarily in the amorphous phase [5]. Chitosan is a derivative of chitin which can be obtained from crab and shrimp shells. Chitosan is produced from deacetylation of chitin to overcome the solubility limitation of chitin in common solvents [6]. Due to the NH2 and OH functional groups that can serve as conjunction sites, chitosan is a good sorbent with high affinity for transition metal ions [7]. Chitosan has good film forming ability, porous scaffolds, and hydrogels [8]. Ion-conducting polymer electrolytes based on chitosan have also been reported [9–16]. From the fundamental point of view, ionic conduction in polymer electrolytes is still poorly understood. Ion transport is complex and depends on factors such as salt concentration, dielectric constant of host polymer, degree of salt dissociation and ion aggregation, and mobility of polymer chains [17]. Dielectric analysis of ion conducting polymer electrolytes can provide information on ion transport behavior and ionic/molecular interaction in solid polymer electrolytes [18]. This is due to the fact that dielectric constant is both frequency and temperature dependent [19]. Recently Petrowsky and Frech [20, 21] hypothesized that the DC conductivity is not only a function of temperature, but also is dependent on the dielectric constant in organic liquid electrolytes. They have
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