| Popis |
Although nanofibers have been known to the scientific community for almost a hundred years, they have long remained on the brink of interest. It was not until the 1990s that there was a renaissance of nanofiber materials research. Thanks to their unique properties, high filtration efficiency, great free surface combined with good breathability, nanofiber materials are directly destined for filtration applications and come to the forefront of industrial interest.[1] At the beginning of the millennium, the last obstacle was solved - the efficient industrial production, and since then nothing has hindered mass commercial production.[2] The recent COVID-19 pandemic, which globally started the mass production of cheap protective devices capable of trapping virus particles, also played a significant role in commercial spreading.[3] The nanofibers fabricated in a thin layer are a very fine material and cannot be easily handled. In practice, this is solved by their application on a carrier substrate, protecting them from damage. Unfortunately, the nanofiber membrane adheres very reluctantly to these substrates, so it must be properly fixed. In industrial production, this is usually solved by a lamination process, which means that the nanofibers are sophisticatedly glued to the substrate with an adhesive and covered with a protective mesh. However, this technique brings several complications and limitations to the useful properties of the resulting material. In addition, the lamination process significantly increases the cost of the production process.[4] Thus, for the production of disposable protective devices, such as respirators or protective suits, alternative possibilities of attaching nanofibers to the carrier are being sought. A relatively elegant method is the application of plasma to a support substrate, on which nanofibers are subsequently applied. If an atmospheric plasma source is used, this technology can be directly implemented in the in-line production process. It is also possible to apply plasma directly to the nanofiber network, which allows us to modify their chemical and physical properties. In this way, we obtain a functional, inexpensive nanomaterial that we can use for products with high added value. [5, 6] In this work, we focused on the use of dielectric barrier discharges in a coplanar arrangement. These plasma sources are able to generate low temperature energetic plasma over a relatively large area. However, barrier discharges generated at atmospheric pressure also have their disadvantages. From a microscopic point of view, the energy in the plasma is focused into tiny channels called streamers. There is a risk that these energy channels can damage the material during treatment and create small holes inside it. In the case of minor damage to the carrier material, this is not yet a significant problem. However, the perforated nanofiber mesh would of course lose its unique filtering ability. In this work, we mainly focused on the preparation of nanomaterial for air filtration, and we will monitor the positive or adverse effect of plasma on filtration efficiency.
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