Synthesis and characterization of surface modified MWCNTs reinforced PVA composite films

Polymers have been ruling the packaging industry for decades due to their versatility, easy manufacturability, and low cost. The overuse of non-biodegradable plastics in food packaging has become a serious environmental concern. Multi-walled carbon nanotube (MWCNT) reinforced nanocomposites have exceptional electrical, thermal, and mechanical properties. However, a major difficulty in the synthesis of CNT-reinforced nanocomposites is the nanotube agglomeration, which results in poor dispersion and less interfacial bonding between reinforcements and matrix, limiting its advantages. Although acid treatment is effective, strong acids, treatment timing, and sonication power can lead to nanotube damage. This study introduces a novel approach to enhance PVA nanocomposite films' mechanical, thermal, optical, and antibacterial performance using polydopamine-coated CNTs, which are more effective than pristine or acid-treated CNTs, making them promising for food packaging applications. Pristine CNT reinforced polyvinyl alcohol (PVA) nanocomposite films were fabricated with varying concentrations of CNTs (0 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt%). These samples underwent mechanical, thermal, and optical characterization for the optimization of CNTs' concentration in the PVA matrix. Then the optimized amount of acid-treated and polydopamine-coated CNTs was used to fabricate PVA/CNT films. The mechanical, thermal, and optical characteristics of the resultant films were investigated. It was found that the polydopamine coating on CNTs improved the mechanical, thermal, and optical properties of the films as compared to those of pure PVA, PVA/pristine CNT, and PVA/acid-treated CNT films. Moreover, the resultant film also demonstrated good antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in comparison to pure PVA.