Unveiling an antimicrobial nonionic surfactant with enhanced surface activity, emulsification, and physicochemical performance

Abstract

: A nonionic surfactant, tetraethylene glycol monopalmitate (PEG4-P), was produced with a 98% yield using a one-step imidazole-catalyzed esterification reaction. Polyethylene glycol (PEG)-based fatty acid esters have been extensively studied, although low-molecular-weight tetraethylene glycol (PEG4) and palmitic acid (PA) derivatives are still relatively less explored. The synthesized surfactant was thoroughly studied using 1 H, 1 C, and 2D NMR spectroscopy, as well as FTIR analysis. PEG4-P has exhibited a lower critical micelle concentration (CMC = 0.0634 ± 0.004 mM). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) demonstrated spherical micellar structures with an average hydrodynamic diameter of 17.6 nm. Additionally, PEG4-P demonstrated better foaming performance, with foaming ability and foam stability of 84.38% and 60.38%, respectively. It has shown satisfactory emulsifying ability with coconut oil over time (1440 min) and created an oil-in-water emulsion. At the air–water interface, thermodynamic and interfacial parameters (Γ max , A min , ΔG mic , ΔG ads , ΔH, and ΔS) revealed effective adsorption and spontaneous micellization. Concentration-dependent MIC and MBC/MFC assays revealed measurable antimicrobial activity against Candida albicans, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus , as well as Escherichia coli and Salmonella typhimurium . Thermal properties, cloud point, solidification temperature, and viscosity were also analyzed in this study. The study recommends PEG4-P as a viable option for detergent, cosmetic, and antibacterial formulations due to its superior emulsifying ability and advantageous physicochemical characteristics.