Fabrication and characterization of Zn-hydroxy double salt-loaded composite: Antimicrobial and flame-retardancy properties

Herein, a novel versatile composite comprising Zn-hydroxy double salt (ZnHDS) and tannic acid (TA) fillers within a polyvinyl alcohol-polyethylene imine (PVA-PEI) mixed matrix (ZnHDS-TA@PVA-PEI) was fabricated and characterized. This composite exhibited dual functionality as an antimicrobial agent and a flame retardant. The composite exhibited significant antimicrobial activity against E. coli and S. aureus strains. The incorporation of ZnHDS into TA@PVA-PEI significantly enhanced its antimicrobial efficacy and flame-retardancy. Clearing zones for the ZnHDS-TA@PVA-PEI against E. coli and S. aureus with 3.8 % ZnHDS loading were obtained as 8.5 and 5.5 mm, respectively. The ZnHDS-TA@PVA-PEI, with a 3.8 % ZnHDS loading, required 18.52 kJ/mol of energy to initiate its thermal decomposition and absorbed a net energy of 41.40 J/g during the process. The maximum weight loss rates for ZnHDS, PVA-PEI, TA@PVA-PEI, and ZnHDS-TA@PVA-PEI were 0.50, 0.75, 0.99, and 0.85 %/°C, respectively. Water solubility tests demonstrated augmented resistance to water with increasing ZnHDS content. The introduction of ZnHDS into TA@PVA-PEI significantly improved the flame-retardancy, was slow to ignite, and self-extinguished within seconds. The thermal decomposition process, antimicrobial activity, and flame-retardancy mechanisms of the composites are discussed. These results, along with the affordability, biocompatibility, and eco-friendliness of ZnHDS, revealed its potential for multiple applications.