Improving the oxygen barrier properties of composite films using green tea extracted CQDs and PVA for active packaging applications

Abstract

Smart food packaging extends the shelf life and preserves the food quality by adding functional agents that make it more appealing. Here, we have used a solvent casting technique to create flexible, transparent, and re-emissive thin films made of polyvinyl alcohol (PVA) and green tea extracts carbon quantum dots (CQDs). The composite films of CQDs/PVA can block UV rays by absorbing them and then re-emitting them in the visible spectrum. Additionally, these films also exhibit a powerful fluorescence emission. The composite film’s capacity to block UV light, hydrophilicity, and oxygen barrier properties was enhanced with varying experimental conditions. We have carried out a comprehensive study to investigate the potential mechanism of the resulting films and how they absorb and re-emit UV radiation. The CQDs/PVA composite films have excellent oxygen barrier properties that can prolong the shelf life of products, keeping them fresh and maintaining their quality. By optimizing the experimental conditions of CQDs in the PVA matrix, the hydrophilicity, and OTR of the composite films were significantly reduced from 40.36 ± 1.41° to 16.23 ± 0.20° and 6.39 ± 0.64 cc/m²·day to 0.34 ± 0.03 cc/m²·day respectively. Water resistance characteristics demonstrate effective H-bonding between CQDs and the PVA matrix, reducing the hydrophilicity of the PVA. The results of our study showed that CQDs have the potential to be utilized as oxygen barriers, UV-blocking coating materials, to make coatings and effective packaging, and to be used in the food industry, pharmaceutical storage, and medical sectors, among other applications.