Hierarchical Porous Ovalbumine-Chitosan Cryogel: Structural Dynamics in Broadband Dielectric Spectroscopy

Abstract

Temperature-dependent A.C. conductivity and dielectric behavior of the Ovalbumin (OVA)-chitosan-n (n-butanol) cryogel as the natural polymer-based hierarchical porous scaffold sample, fabricated by cryogelation/phase separation method, was examined in the frequency range 0.1 Hz-20 MHz and within a temperature range of 293-373 K using Novocontrol Alpha-A high-resolution dielectric, conductivity, and impedance analyzer. The frequency and temperature dependence of the dielectric behavior are explained by the polarization mechanisms in the structure. It was found that the dielectric constant of the samples at heating has higher values than their dielectric constant at cooling. This indicates that the samples need annealing to remove the solvent residue present in their structure. Jonscher's power law fitting has been used to verify our experimental data of conductivity spectra. The nature of variation of exponent (s) obtained from the fitting follows the correlated barrier hopping (CBH), as the predominant conduction mechanism in the sample where the s is found strongly temperature dependent, was observed for the A.C. conductivity sigma ac. According to the impedance data simulation, the system's dielectric behavior can be accurately represented using a parallel RC electrical equivalent circuit. The fittings of the experimental results were performed using equivalent circuits.