Marija Gorjanc

The surface modification of cellulose fibres to create super-hydrophobic, oleophobic and self-cleaning properties

The surface modification of cellulose fibres was performed with the use of low-pressure water vapour plasma, followed by the application of a pad-dry-cure sol-gel coating with the water- and oil-repellent organic-inorganic hybrid precursor fluoroalkyl-functional siloxane (FAS), with the aim of creating the “lotus effect” on the cotton fabric surface. The tailored “lotus effect” was confirmed by measurements of the contact angle of water (154°) and n-hexadecane (140°), as well as by measurements of the water sliding angle (7°), which were used to identify the super-hydrophobic, oleophobic and self-cleaning properties of the modified fibres. The chemical and morphological changes caused by modifications of the fibres were investigated by XPS, FTIR, AFM and SEM. The results show that the plasma pre-treatment simultaneously increased the surface polarity, average roughness, and surface area of the fabric. The application of the FAS coating after plasma pre-treatment caused only a slight increase in the surface roughness, accompanied by a decrease in the surface area, indicating that the architecture of the surface was significantly changed. This result suggests that the surface pattern affected the “lotus effect” more than the average surface roughness. The plasma pre-treatment increased the effective concentration of the FAS network on the fabric, which resulted in enhanced repellency before and after repetitive washing, compared with that of the FAS-coated fabric sample without the plasma pre-treatment. Despite the fact that the plasma pre-treatment increased the concentration of the oxygen-containing functional groups on the fabric surface, this phenomenon insignificantly contributed to the adhesion ability and, consequently, the washing fastness of the FAS coating.

Functionalization of PET fabrics by corona and nano silver

In this work, the antibacterial and other properties of polyester fabrics previously functionalized by corona and/or silver nano particles have been studied. Corona air plasma was used as a pretreatment of raw, washed and washed-thermostabilized polyester fabrics to increase the adhesion of nano silver particles resulting in an excellent antibacterial effect. X-ray photoelectron spectroscopy was applied to analyze the surface composition and chemical bonding of the surface atoms on untreated and treated fabrics. The surface morphological changes of polyester fibers were observed by scanning electron microscopy (SEM). The quantity of silver on the polyester fabrics was determined by the use of the inductively coupled plasma-atomic emission spectrometry method. The antimicrobial properties of functionalized polyester fabrics were tested according to American Society for Testing and Materials ASTM Designation: E 2149-01. Additionally, the dyeing of polyester fabrics with selected disperse dye as well as capillary action tests were performed to confirm the chemical and morphological changes of polyester fibers after corona treatment. Considerable differences in surface composition were found between the raw and washed or washed-thermostabilized fabrics. The surface of raw fabrics is richer in carbon and the concentrations of the C—O and O—C=O groups are lower than on the other samples. An opposite effect is observed for washed and washed thermostabilized fabrics. SEM analyses show that the plasma treatment also affects the surface morphology. The chemical surface composition and morphology are highly related to the hydrophobicity and hydrophylicity, and the achievement of better nano silver adhesion and enhanced dyeing and antimicrobial properties of differently prepared corona plasma-treated polyester fabrics. Therefore, corona air-treated raw polyester fabrics demonstrated optimum antimicrobial properties due to the excellent adhesion of nano silver.

CF4 plasma and silver functionalized cotton

In an attempt to use minimal concentrations, initially, of silver nanoparticles for loading onto textiles and to achieve maximum concentrations on the material, CF4 low-pressure plasma was used on bleached and mercerized cotton fabric. The concentrations of silver on the fabrics were determined by the ICP-MS method (inductively coupled plasma-mass spectrometry), the morphology of fiber surfaces was observed with a scanning electron microscope (SEM), and an x-ray photoelectron spectroscopy (XPS) study was used for the evaluation of surface chemical changes. The antibacterial effect of silver loaded fabrics was tested against Enterococcus faecalis and Pseudomonas aeruginosa. The best results were found for plasma-treated cotton fabric functionalized with 30 nm silver particles. The results show effective plasma etching of the fabric surface, which caused excellent adhesion of silver particles. Color measurements of dyed samples showed that CF 4 plasma does not affect the color of dyed cotton. The mechanical properties of cotton remain unaltered after plasma treatment.

Functionalization of Polyester Fabric by Ar/N2 Plasma and Silver

The objective of this research was to use Ar/N2 (50%:50%) plasma to increase the adhesion of nano silver particles to raw polyester fabric. RUCO-BAC AGP was applied using the exhaust method. X-ray photoelectron spectroscopy revealed differences in surface composition between the Ar/N2 plasma-treated and untreated raw fabrics. The Ar/N2 plasma treatment was found to increase the surface carbon concentration and decrease the concentration of C-O and O-C=O groups on the surface. After plasma etching, the specific surface of the polyester fabric and properties related to it were found to change significantly. This change was confirmed by a decrease in the whiteness index and an increase in the dyeability of the polyester fabric with disperse dye. Morphological changes in the surface of plasma-treated polyester fabric enabled greater adhesion of nano silver particles and increased the antimicrobial effect with respect to Pseudomonas aeruginosa, Escherichia coli and Streptococcus faecalis.

The Influence of Water Vapor Plasma Treatment on Specific Properties of Bleached and Mercerized Cotton Fabric

The influence of water vapor plasma on chemical, morphological and mechanical properties of bleached and mercerized cotton fabric was studied. Reactive exhaust dyeing was used for loading of nano silver. Inductively coupled plasma mass spectroscopy results show that plasma treatment enhanced nano silver adhesion to the fabric, which also contributed to antimicrobial effectiveness to Pseudomonas aeruginosa and Escherichia coli. Surface changes of plasma treated cotton were observed with scanning electron microscopy. Xray photoelectron spectroscopy results show the decrease of C—C bonds in favor of C—O, O—C—O, C=O, and O=C—O bonds and higher O/C atomic ratio in plasma treated fibers. Mechanical properties of cotton yarn after plasma treatment remained unchanged.

The influence of vat dyeing on the adsorption of synthesized colloidal silver onto cotton fabrics

Bleached, mercerized cotton fabrics were used in this research. In the first phase, the dyeing of cotton fabrics with a blue vat dye Bezathren Blau BCE was performed, and in the second phase, the dyed fabrics were immersed into a colloidal silver solution. The colloidal silver solution was prepared via synthesis from AgNO3 and reduced with NaBH4. Parent cotton fabrics were also immersed into the colloidal silver solution. A comparison of the quantity of silver on the parent and vat-dyed cotton fabrics was performed. Inductively coupled plasma mass spectrometry revealed a silver content that was almost two times higher on the dyed and silver-treated cotton fabrics. All samples (parent and dyed) treated in the colloidal silver solution showed excellent antimicrobial activity. The fiber surfaces were imaged using a scanning electron microscope. The mechanical properties of vat-dyed and vat-dyed silver-treated fabrics and the wash fastness of silver-treated samples were determined.

Application of extremely non-equilibrium plasmas in the processing of nano and biomedical materials

Some applications of extremely non-equilibrium oxygen plasma for tailoring the surface properties of organic as well as inorganic materials are presented. Plasma of low or moderate ionization fraction and very high dissociation fraction is created by high frequency electrodeless discharges created in chambers made from a material of low recombination coefficient. The O atom density often exceeds 1021 m−3 which allows for rapid functionalization of carbon-containing materials. Surface saturation with polar oxygen-rich groups is achieved in a fraction of a second and further exposure leads to etching. The etching is often non-uniform and results in nano-structuring of surface morphology. A combination of rich morphology and saturation with polar functional groups allows for a super-hydrophilic character of originally hydrophobic materials. Polymer composites are etched selectively so the polymer component is removed from the sample surface, leading to modified surface properties. Furthermore, such a treatment allows for distinguishing the distribution and orientation of fillers inside the polymer matrix. The exposure of inorganic materials to non-equilibrium oxygen plasma causes one-dimensional growth of metal oxide nanoparticles, thus representing a unique technique for the rapid catalyser-free growth of nanowires.

Functionalization of cellulose fibres with oxygen plasma and ZnO nanoparticles for achieving UV protective properties

Low-pressure oxygen plasma created by an electrodeless radiofrequency (RF) discharge was applied to modify the properties of cellulosic fibrous polymer (cotton) in order to improve adsorption properties towards zinc oxide (ZnO) nanoparticles and to achieve excellent ultraviolet (UV) protective properties of cotton fabric. The chemical and physical surface modifications of plasma-treated cotton fabric were examined by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The mechanical properties of plasma-treated samples were evaluated, measuring strength and elongation of the fabrics. The quantity of zinc on the ZnO-functionalized cotton samples was determined using inductively coupled plasmamass spectrometry (ICP-MS) and the effectiveness of plasma treatment for UV protective properties of cotton fabrics was evaluated using UV-VIS spectrometry, measuring the UV protection factor (UPF). The results indicated that longer plasma treatment times cause higher concentration of oxygen functional groups on the surface of fibres and higher surface roughness of fibres. These two conditions are crucial in increasing the content of ZnO nanoparticles on the fibres, providing excellent UV protective properties of treated cotton, with UPF factor up to 65.93.

Influence of oxygen plasma pre-treatment on the water repellency of cotton fibers coated with perfluoroalkyl-functionalized polysilsesquioxane

Oxygen plasma pre-treatment was applied to cotton fabric with the aim of improving the water repellency performance of an inorganic-organic hybrid sol-gel perfluoroalkyl-functionalized polysilsesquioxane coating. Cotton fabric was pre-treated with low-pressure oxygen plasma for different treatment times and operating powers. Afterward, 1H,1H,2H,2H-perfluorooctyltriethoxysilane (SiF) was applied to the cotton fabric samples using the pad-dry-cure method. The surfaces of the untreated and modified cotton fibers were characterised using Fourier transform infrared spectroscopy, Xray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. The water repellency of the SiF-coated fabric samples was evaluated using static and sliding contact angle measurements with water. The results show that the plasma treatment with the shortest treatment time (10 s) and the lowest operating current (0.3 A) increased the atomic oxygen/carbon ratio of the cotton fiber surface from 0.6 to 0.8 and induced the formation of a nano-sized grainy surface. Increasing the plasma treatment time and/or operating current did not intensify the surface changes of the cotton fibers. Such saturation effects were explained by the large influence of reactive oxygen atoms during the plasma treatment. The measured static water contact angles on the surface of the untreated and plasma pre-treated and SiF-coated cotton fabrics showed that the oxygen plasma pre-treatment enabled the increase of the water contact angle from 135° to ≈150°, regardless of the applied plasma treatment time and discharge power. This improvement in the hydrophobicity of the SiF coating was followed by a decrease in the sliding angle of water droplets by more than 10° compared to the plasma untreated and SiF-coated sample characterized by a water sliding angle of 45°. Additionally, measurements of the water sliding angle revealed that the increase of the static contact angle from 149° to 150° corresponded to a drop of the water sliding angle from 33 to 24°, which suggests that the plasma pre-treatment of 20 s at an operating current of 0.3 A produced the best water-repellent performance of the SiF-coated cotton fabric.

Multifunctional Textiles – Modification by Plasma, Dyeing and Nanoparticles

The textile industry in developed countries is confronting the world’s marketing conditions and competitive challenges which are driving towards the development of advanced, highly functional textiles and textiles with higher added value. The conventional textile finishing techniques are wet chemical modifications where water and rather hazardous chemicals are used in large quantities and wastewaters need to be processed before discharging effluent, whereas the most problematic factor are ecological impacts to the environment and effects to human health. The increasing environmental concerns and demands for an environmentally friendly processing of textiles leads to the development of new technologies, the use of plas‐ ma being one of the suitable methods [1]. Plasma technology is an environmentally friendly technology and a step towards creating solid surfaces with new and improved properties that cannot be achieved by conventional processes [2]. Plasma is the fourth state of matter. It is a gas with a certain portion of ionized as well as other reactive particles, e.g. ions, elec‐ trons, photons, radicals and metastable excited particles. Several types of plasma are known; however, only non-equilibrium or cold plasma is used for the modification of physical and chemical properties of solid materials such as textiles. Chemically reactive particles pro‐ duced at a low gas temperature are a unique property of cold plasma; hence, there is mini‐ mal thermal degradation of a textile substrate during the plasma processing [3]. Cold plasma is a partially ionized gas with the main characteristic of a very high temperature of free electrons (typically of the order of 10,000 K, often about 50,000 K) and a low kinetic tem‐ perature of all other species. The average energy of the excited molecules is usually far from the values calculated from the thermal equilibrium at room temperature. The rotational tem‐ perature, for instance, is often close to 1000 K, while the vibrational temperature can be as