19.09.2018 change 19.09.2018

Water resistant natural fluff? Scientists from Łódź obtain this result with "cold plasma"

Photo: Fotolia Photo: Fotolia

Ceramic fabrics and tiles, on which water flows down, cleaning the surface; natural fluff that maintains thermal properties, even if water gets into it - these are some of the results developed with the use of cold plasma by scientists at the Lodz University of Technology.

Professor Jacek Tyczkowski from the Faculty of Process and Environmental Engineering, Lodz University of Technology reminds that plasma is the fourth state of matter - together with solids, liquids and gases. It is a gas in the ionised state, a mixture of free electrons, ions, radicals, radical ions, excited molecules. The ratios of these elements determine the type of plasma - he explains.

Plasma is found in stars, including the Sun (thermal plasma), in lamps, in atmospheric discharges and in the northern lights. In chemical technology, one of its types, cold (non-thermal) plasma, is used to manufacture new materials or to modify their surfaces.

"In cold plasma, only electrons have high energy, while all other components are close to room temperature. Thus, products of chemical transformations are not destroyed. That is why it is so valuable and interesting for chemical technology" - emphasises Prof. Jacek Tyczkowski.

Plasma allows to manufacture completely new materials in the form of very thin nanostructured layers with fascinating properties that can not be obtained by other methods. This plasma can also be used to modify the surfaces of conventional materials, completely changing their properties.

"We can, for example, cause a surface to cease to be willing to come into contact with water and become hydrophobic or even superhydrophobic. If we modify it with plasma, then even with a small inclination the drops of water fall from it, taking dirt particles with them. This phenomenon of self-cleaning of surfaces is known from nature, for the first time it was observed on lotus leaves, hence its name +lotus effect+" - explains the expert.

Plasma also allows to obtain the opposite effect and create hydrophilic or superhydrophilic layers that perfectly moisten and cover with water. It is also possible to change the adhesive properties (adherence) of materials and, for example, improve the gluing properties of surfaces. "When it comes to surface modification with plasma, there are many possibilities" - the scientist emphasises.

Researchers from the Faculty of Process and Environmental Engineering have already developed plasma method of fabric surface modification. They used plasma to create superhydrophobic layers on fabrics, causing the water (that soaked into the fabric before the plasma treatment) to flow down the surface and cause the self-cleaning effect. This solution can be used in the production of rainwear, among other things.

Currently, scientists are working on the method of modification of ceramic tiles, for example bathroom tiles. The desired result are tiles, on which the water will flow down so they will not have to cleaned dried too often after bathing. This effect can also be achieved by appropriate plasma treatment. "Drops on such tiles flow down like on lotus leaves and clean their surface" - notes the scientist.

Researchers also used plasma to modify the surface of natural fluff. Fluff is a great insulating material, as long as it doesn`t get wet. Then it loses its thermal properties. In this case, the challenge was to develop a method that will prevent the water from wetting down the fluff.

"A thin nanostructure is applied to the surface of feathers. This way, the fluff gains a protective barrier, which means that even if water gets into it, it can not moisten it and its drops remain completely separate" - says Prof. Tyczkowski.

Such plasma fluff has already been tested in overalls for climbers, for example during the last National K2 Expedition. "With this plasma fluff, even if you fall into the water, cloths remain dry inside and retain their thermal properties" - adds the expert.

Another successful project of researchers from Łódź concerns the modification of the surface of rubbers used as soles for shoes, during their preparation for gluing processes. According to the researchers, the revolutionary method is based on changing the technology used in the footwear industry.

Until now, rubber surfaces have been chemically activated using organic solvents and volatile chlorine compounds that are harmful to humans and the environment. Thanks to the use of plasma, a clean, waste-free "green chemistry" technology has been developed. Better results have been obtained than with traditional chemical methods.

PAP - Science in Poland, Kamil Szubański

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