Sustainable antibacterial nanocoating from polycaprolactone grafted with dapsone and silver nanoparticles for boosting the properties of bagasse paperboard for active food packaging

Abstract

Nanocoating technology for by-product bagasse papers (BPs) utilizes hybrid polymers to create a superhydrophobic surface that enhances several properties of the BP material, which is highly promising for many applications, including active food packaging. Thus, this study aimed to prepare a functional nanocoating from polycaprolactone (PCL) grafted with dapsone (DAP) and silver nanoparticles (Ag NPs) for promoting the properties of hydrophilic BPs. The outcome of grafting DAP into PCL, as well as the interactions between the components after the coating process, were investigated by FT-IR and XRD analyses. Varied contents of the Ag NPs (i.e., 0.05%, 0.15%, and 0.30%) were used to fabricate a PCL-DAP–Ag nanocoating for treating the hydrophilic BPs using a dip-coating approach. The net-treated BPs (TBPs) were subjected to various analyses and tests, including morphological tests by XRD and SEM analyses, mechanical and barrier property evaluation, wettability assessment by the water contact angle (WCA), flammability resistance testing, and antibacterial activity measurements. The results revealed that most of the properties of the TBPs were further enhanced by the presence of Ag NPs, especially at 0.15%, compared to raw BP or unfilled TBP. The flammability resistance of TBP-0.30% Ag was achieved when the Ag NP content in the nanocoating reached 0.30%. Moreover, the treated BPs demonstrated superior antibacterial activity, which effectively killed microbes and inhibited their growth within an inhibitory zone ranging from 14 to 33 mm, depending on the microbe and sample type. In summary, PCL grafting is influential, and applying PCL-DAP-based Ag NPs as a nanocoating to hydrophilic BPs presents a highly promising strategy for antimicrobial food packaging applications.