Development of MgO-reinforced Chitosan–CMC/ZnO Nanocomposite Films for Photocatalytic and Antimicrobial Applications

Abstract

Chitosan–carboxymethyl cellulose/ZnO–MgO (Chitosan–CMC/ZnO–MgO) nanocomposite films were fabricated and evaluated for their thermal, structural, dielectric, mechanical, photocatalytic, interfacial, and antimicrobial characteristics. FT-IR showed interactions between polymer chains and incorporated nanoparticles, while SEM indicated relatively uniform particle dispersion throughout the matrix. XRD patterns verified the crystalline phases of magnesium oxide (MgO) and zinc oxide (ZnO), including the characteristic ZnO (101) reflection. Increasing the MgO concentration enhanced the thermal resistance of the films. Kissinger calculations showed that the activation energy (Ea) increased from 86 kJ/mol for the MgO-free film to 122 kJ/mol for the 3% MgO formulation. DSC measurements similarly revealed a rise in the glass-transition temperature (Tg) from 98.5 °C to 117 °C. Tensile strength improved from 28.6 MPa to 51.6 MPa, while Shore A hardness increased from 41.8 to 62.7. MgO incorporation also increased the dielectric constant. Surface wettability decreased, as demonstrated by the increase in the water contact angle from 71.26° to 93.17°. Under UV irradiation, crystal violet degradation increased from approximately 25% for the MgO-free film to 51% for the 3% MgO film. The same formulation generated inhibition zones of 15.28, 14.39, and 16.12 mm against C. albicans, E. coli, and S. aureus. Overall, MgO incorporation improved mechanical performance, enhanced photocatalytic efficiency, and showed promising preliminary antimicrobial activity. The developed films therefore offer potential for environmental treatment and antimicrobial surface applications. Nevertheless, before considering biomedical use, researchers must investigate their biocompatibility, cytotoxicity, long-term stability, and nanoparticle release.