Bifunctional Water-Based Alkyl Ketene Dimer Nanoparticles for Fabricating Cotton Fabrics with Hydrophobicity and Antimicrobial Properties

Abstract

Modifications of natural fabric’s surfaces are typically achieved by chemically or physically incorporating functional agents (water-repellent and antimicrobial properties) into the fabric’s fibers. Regarding environmental concerns and health safety, a treatment process employing a water-applicable or emulsion form is preferred in manufacturing hygiene-grade products, e.g., face masks. In this study, a water-based dispersion of alkyl ketene dimer (AKD) nanoparticles (a hydrophobic agent) was fabricated by a facile oil-in-water emulsion with an ultrasonication-assisted process, followed by solvent evaporation. Aiming to stabilize AKD emulsion and provide antimicrobial properties, a phosphatidylcholine (PC) molecule containing a choline group and a phosphate moiety was selected as a surfactant. The obtained water-based AKD nanoparticles showed high stability and were monodispersed with an average size of 182.5 ± 1.0 nm. The AKD nanoparticle dispersion was then applied to the cotton fabric’s surfaces by ultrasonic spraying. Fourier transform infrared spectra indicated the chemical reactions between AKD and hydroxyl groups of the cotton fabric’s cellulose structure. This enhanced the hydrophobicity of the fabrics with a water contact angle of 137 ± 3°. SEM-EDX results revealed a rough surface with a good distribution of C, O, and P elements, reflecting that AKD molecules fully cover the surface of the cotton fabrics. After 20 washing cycles, including UV exposure, the treated fabrics still showed high water repellency, indicating high durability. Moreover, the treated fabric showed an efficiency against both Gram-positive and Gram-negative bacteria, S. aureus and E. coli, of 94.7 and 70.2%, respectively. The results demonstrate that the treatment with water-based AKD nanoparticles effectively imparted the cotton fabric with durable water-resistant and antimicrobial properties due to the chemical bonding formed between fabric fiber and AKD molecules and the synergistic effect of the hydrophobicity of AKD and charged groups of PC surfactant.