Antibacterial activity and dielectric properties of the PVA/cellulose nanocrystal composite using the synergistic effect of rGO@CuNPs

Abstract

This work aims to enhance the performance of the polyvinyl alcohol (PVA) composite by using cellulose nanocrystal (CNC) as reinforcement and copper nanoparticles (CuNPs)/reduced graphene oxide (rGO) as conducting and antimicrobial reagents. Firstly, rGO was loaded onto CuNPs using an eco-friendly microwave method. Different techniques characterized the components and prepared composites, which indicated the incorporation of cellulose nanocrystals and rGO@CuNPs within the polyvinyl alcohol matrix. Utilizing the clear zone of inhibition, the antibacterial test was quantified. Compared to the neat composite, the rGO@CuNPs loaded polyvinyl alcohol/ cellulose nanocrystal composites exhibited no bacterial growth against S. aureus, E. coli, and C. albicans. However, all composites did not have antifungal activity against A. niger. The combination of conductivity and interfacial polarization is the reason for the abrupt increase of permittivity with decreasing frequency. Besides, adding rGO@CuNPs improved the electrical conductivity. DC-Conductivity increased about a decade after adding cellulose nanocrystal to polyvinyl alcohol, then another decade after adding CuONPs. The electric loss modulus representation shows a systematic shift in the peak position towards higher frequencies, decreasing the so-called conductivity relaxation time. This is the main reason for the enhancement of conductivity. The systematic attenuation of peaks' height with increasing conductivity is still unclear.