Preparation And Characterization Of Nanostructured Antibacterial Nonwovens

Silver antimicrobial is the most widely used antibacterial finishing agents. Besides the excellent antibacterial effects, nanostructured silver has such advantages as low toxicity to human beings, easy to be dispersed in water, no tolerance, not affected by pH value and good thermal stability. Thus, preparation of antibacterial materials has aroused increasing attention from the people all over the world.In this paper, classification of the antibacterial finishing agents and techniques employed for the preparation of the nanostructured silver antibacterial textiles home and abroad were first introduced. For there are drawbacks existing in these available techniques, in this research, magnetron sputter coating which is friendly to the environments was used to deposit nanostructured silver films on polypropylene (PP) and PLA nonwovens at room temperature to obtain the antibacterial properties.In this research, the impacts of sputtering parameters such as deposition time, sputtering power, gas pressure and gas flow on antibacterial properties of the samples were investigated. Furthermore, the effect of argon plasma pretreatment for nonwovens on antibacterial properties was also studied. The antibacterial performance was assessed using shake flask test. The surface morphology was observed with SEM and AFM. Surface elemental distribution and elemental quantitative analysis was measured employing EDX. The antibacterial test results revealed that deposition time and argon plasma pretreatment were the two key factors affecting antibacterial properties of the coated materials, while sputtering power, gas pressure and gas flow had slight influence on antibacterial properties. Within the scale of experiment, antibacterial performance was significantly improved as the deposition time prolonged. For PP nonwovens, when the silver film thickness was above 3nm, both the reduction percentage of Staphyllococcus aureus and Escherichia coli bacteria got to 100%; while for PLA nonwovens, as the coating thickness exceeded 2nm, both the reduction percentage reached 100%. Under the same processing condition, the coated samples with argon plasma pretreatment had the better antibacterial performance. And respectively for the pretreated PP and PLA nonwovens, when the film thickness got to 2nm and 0.5nm, the reduction percentage of both the tested bacteria reached 100%. AFM and EDX analysis indicated that as the deposition time prolonged, the coverage of the silver particles on nonwovens and silver weight percentage per unit surface increased, leading to an increase in release rate of silver ions from coating, which resulted in the improved antibacterial properties. The process of argon plasma treatment resulted in the formation of obvious etch dot and flute on fibers of nonwovens, thus the sputtered silver particles were hard to cluster, leading to the increased activity of nanostructured silver on films, which contributes to the improved antibacterial performance. Moreover, after plasma pretreatment, the overall amount of silver particles deposited on nonwovens increased, resulting in the improved antibacterial properties.Under the same deposition conditions, there were differences in antibacterial performance between the coated PP and PLA nonwovens, which were caused by the roughness and hydrophilicity difference between the materials.