Thin and flexible Mg<sub>0.7</sub>Ni<sub>0.3</sub>Fe<sub>2</sub>O<sub>4</sub> nanoparticle-reinforced chitosan/ polyvinyl alcohol bionanocomposite films with tunable dielectric properties for energy storage devices

Misirlioglu B. S., BERBER H., Gul E., Oladipo A., Gazi M.

INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES, cilt.339, 2026 (SCI-Expanded, Scopus)

Özet

The development of flexible, eco-friendly materials is critical for next-generation energy storage devices. Herein, novel bionanocomposite films were fabricated by dispersing non-stoichiometric Mg0.7Ni0.3Fe2O4 spinel ferrite nanoparticles (up to 20 wt%) into a chitosan/polyvinyl alcohol (CS/PVA) matrix. A comprehensive analysis of the structure-property relationships was performed. The incorporation of nanoparticles resulted in a trade-off in mechanical properties: while tensile strength decreased from 56.5 MPa to 13.4 MPa, flexibility was greatly enhanced, with elongation at break increasing by 270 % (from 2.35 % to 8.75 %). Thermogravimetric analysis confirmed improved thermal stability, with the main polymer degradation temperature increasing by over 20 degrees C. The dielectric properties were dramatically enhanced due to Maxwell-Wagner-Sillars polarization, with the dielectric constant (epsilon') at 10 Hz surging from 25.7 to 7433.9. Correspondingly, the AC conductivity at 1 kHz increased by over two orders of magnitude. The composites demonstrated pseudocapacitive behavior, achieving a maximum specific capacitance of 40.7 F/g and an energy density of 0.19 Wh/kg for the 20 wt% film. Spectroscopic and microscopic analyses confirmed that strong interfacial interactions between the well-dispersed nanoparticles and the polymer matrix were responsible for these enhancements. This work demonstrates that incorporating engineered ferrite nanoparticles into a biopolymer matrix is a highly effective strategy for creating flexible, high-performance dielectrics for sustainable energy storage applications.