Choline and amino acids-based ionic liquids (CABILs) for the preparation of new antibacterial coating with loofah and epoxy resin

As an ideal raw material for composite materials, loofah sponge has shown the advantages of high strength, ideal toughness, good degradability and economy. In this study, a new tri-component antibacterial coating composed of loofah fiber, epoxy resin and choline-amino acid ionic liquids (CABILs) was successfully developed. Firstly, three CABILs, including choline lysine [Ch][Lys], choline arginine [Ch][Arg], and choline histidine [Ch][His], were successfully synthesized and identified. Then they were used to dissolve loofah fiber from the raw material with the highest dissolution rate up to (36.00 ± 0.32) wt%, and the product was further applied for bisphenol F epoxy resin to achieve the effect of modification and curing. The CABILs played multiple roles including dissolver, dispersant, curing agent and bacteriostatic enhancer. The resulted coating was characterized by various ways, and the traditional curing agent 4,4′-diaminodiphenylmethane was also compared as the control. After the antibacterial tests, two composite coating materials with expected performance, which resulted from [Ch][Lys] and [Ch][Arg] as curing agents; and the sample with the strongest activity against S. aureus had an antibacterial rate of (81.198 ± 0.041)%. In addition, the durability for their structure, basic properties and antibacterial effect of the coating materials were investigated and validated, providing basic data and valuable reference for the development of new functional coatings with crop products and green solvents.