Imparting superhydrophobic and antibacterial properties onto the cotton fabrics: synergistic effect of zinc oxide nanoparticles and octadecanethiol

In this research, a one-step method for the preparation of superhydrophobic and antibacterial cotton fabric is presented, which has been modified by zinc oxide (ZnO) nanoparticles and octadecanethiol (ODT). The individual use of ZnO and ODT resulted in superhydrophilic fabrics whereas their combined use caused a transformation to the superhydrophobic behavior. Based on the morphological analysis, the distribution of ZnO nanoparticles on the fabrics’ surfaces was notably improved leading to a much more uniform rough structure. Such proper level of roughness along with the hydrophobicity induced by ODT were found responsible for the observed high contact angle (161°). The deposition of ZnO and ODT on the fabrics’ surfaces was further proved by X-ray photoelectron spectroscopy. The bacterial adhesion experiments revealed that even the sole presence of ODT could notably reduce the bacterial attachment to the fabric due to the reduced surface free energy. The individual use of ZnO nanoparticles was found to have a strong antibacterial effect on both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria. The bacterial adhesion was even further diminished upon the combined use of ZnO and ODT. The numbers of adhered S. aureus and E. coli cells were highly reduced from 438,000 and 192,000 CFU cm⁻² for the pristine fabric to 600 and 48 CFU cm⁻² for the superhydrophobic fabric, respectively. Simultaneous achievement of superhydrophobicity and antibacterial activity on the fabrics’ surfaces could have promising potential in the hospital garments and facemasks where patients and staff need to be protected from the infections.