Victoria Dutschk

Effects of Topographic Structure on Wettability of Differently Woven Fabrics

Optical analysis of roughness operating on the principle of chromatic aberration and dynamic wetting measurements have been used to investigate the surface properties of polyester fabrics with different woven structures. The results revealed differences in the two basic types of weave — plain and twill — with respect to the penetration behavior of water. Additionally, plain weave fabrics were manufactured using differently profiled fibers — round and cruciform. It was established that fabrics composed of fibers having a cruciform cross section are more hydrophobic than those that are round. It was shown that topographical characteristics of the fabrics strongly depend on their construction parameters such as the type and fineness of filaments, yarn fineness, yarn density, and, consequently, the type of weave. The results provide further insight into the relationship between construction parameters of fabrics of the same chemical nature and their topographic and wetting properties.

Advances in Topographic Characterization of Textile Materials

All textile materials, having periodic surfaces, show horizontal and vertical repetitive unities. For this reason, different length scales have to be taken into account by interpreting topographic data measured. In this study, a topographical characterization method for textile materials at different length scales is presented and justified. The topographical study of textile materials using different length scales permits us to characterize the surfaces considering their specific morphologies due to the type of weave, yarn and filament/ fibers separately. The use of a scale concept to characterize textile surfaces seems to be a new skill that helps to correlate textile parameters, topography, and topographical changes with interface phenomena such as spreading, wetting, capillary penetration, and soil release.

Innovative sol-gel route in neutral hydroalcoholic condition to obtain antibacterial cotton finishing by zinc precursor

In the present study, a possibility to realize a transparent sol by zinc-based precursors in a neutral medium without acidic or alkaline catalyst was investigated. Moreover, to study the influence of an inorganic–organic hybrid polymer on the proposed antibacterial finishing, the Zn-based sol was mixed with 3-glycidoxypropyltrimethoxysilane (GPTMS), a hybrid sol–gel precursor, to produce zinc-containing silica coatings on the cotton fibres. An optimization of functionalization process parameters was performed by monitoring survival rate of Escherichia coli bacteria. Finally, selected finishes were tested in respect to their antibacterial activity using potential pathogenic bacteria Staphylococcus aureus and Klebsiella pneumoniae. Sol–gel synthesized cotton finishes based on nano-Zn acetate without and with GPTMS showed larger bactericidal and bacteriostatic activities. The both types of finishes also show hydrophobic effect within the first eliminates the hydrophobicity effect and reduces antibacterial activity. The results are very promising, since the antibacterial activity of cotton is comparably high and the finishing procedure is cheap and can be easily performed.

Smart and green interfaces: From single bubbles/drops to industrial environmental and biomedical applications

Interfaces can be called Smart and Green (S&G) when tailored such that the required technologies can be implemented with high efficiency, adaptability and selectivity. At the same time they also have to be eco-friendly, i.e. products must be biodegradable, reusable or simply more durable. Bubble and drop interfaces are in many of these smart technologies the fundamental entities and help develop smart products of the everyday life. Significant improvements of these processes and products can be achieved by implementing and manipulating specific properties of these interfaces in a simple and smart way, in order to accomplish specific tasks. The severe environmental issues require in addition attributing eco-friendly features to these interfaces, by incorporating innovative, or, sometimes, recycle materials and conceiving new production processes which minimize the use of natural resources and energy. Such concept can be extended to include important societal challenges related to support a sustainable development and a healthy population. The achievement of such ambitious targets requires the technology research to be supported by a robust development of theoretical and experimental tools, needed to understand in more details the behavior of complex interfaces. A wide but not exhaustive review of recent work concerned with green and smart interfaces is presented, addressing different scientific and technological fields. The presented approaches reveal a huge potential in relation to various technological fields, such as nanotechnologies, biotechnologies, medical diagnostics, and new or improved materials.

Surface roughness and wettability of wool fabrics loaded with silver nanoparticles: Influence of synthesis and application methods

Hydrophilization of wool fabrics was performed by silver nanoparticles with different surface charge using three different methods: exhausting, pad–dry–cure and in situ synthesis. Dynamic wetting measurements and surface topography analysis were used to evaluate surface changes on wool fabrics. The wool samples in situ loaded revealed the highest fabric roughness and porosity, while the use of the pad–dry–cure method leads to the lowest fabric porosity, and its roughness values approximately were the same as those for samples loaded with the exhaustion method. The results revealed that loading silver nanoparticles with high surface charges onto wool fabrics via the exhaustion method can significantly improve the hydrophilicity of wool fibre surface. The possible reasons for this improvement are discussed.

Functional finishing of aminated polyester using biopolymer-based polyelectrolyte microgels

This study focuses on a microgel-based functionalization method applicable to polyester textiles for improving their hydrophilicity and/or moisture-management properties, eventually enhancing wear comfort. The method proposed aims at achieving pH-/temperature-controlled wettability of polyester within a physiological pH/temperature range. First, primary amine groups are created on polyester surfaces using ethylenediamine; second, biopolymer-based polyelectrolyte microgels are incorporated using the natural cross-linker genipin. The microgels consist of the pH-responsive natural polysaccharide chitosan and pH/thermoresponsive poly(N-isopropylacrylamide-co-acrylic acid) microparticles. Scanning electron microscopy confirmed the microgel presence on polyester surfaces. X-ray photoelectron spectroscopy revealed nitrogen concentration, supporting increased microscopy results. Electrokinetic analysis showed that functionalized polyester surfaces have a zero-charge point at pH 6.5, close to the microgel isoelectric point. Dynamic wetting measurements revealed that functionalized polyester has shorter total water absorption time than the reference. This absorption time is also pH dependent, based on dynamic contact angle and micro-roughness measurements, which indicated microgel swelling at different pH values. Furthermore, at 40 °C functionalized polyester has higher vapor transmission rates than the reference, even at high relative humidity. This was attributed to the microgel thermoresponsiveness, which was confirmed through the almost 50% decrease in microparticle size between 20 and 40 °C, as determined by dynamic light scattering measurements.

Effect of Cellulase Enzyme on Cellulose Nano-topography

Abstract In this study, modification effects of cellulose foil by cellulase enzyme are studied in respect to topography changes by means of atomic force microscopy (AFM). The results provide useful information to understand the enzyme action in the amorphous and crystalline regions of cellulose. It was revealed, that the treatment of cellulose with the cellulase enzyme depends on its concentration, which selectively attacks amorphous cellulose regions. At lower concentration, a random surface roughening of the cellulose foil was observed. With increasing enzyme concentration, the cellulose surface became smoother. On the basis of this knowledge, a conceptual model to describe the conditioning effect by cellulase on the cleanability of cotton fabrics was developed. With the help of this model, we are able to estimate changes in the nanoporosity of cotton fibres.

Interaction of solutions containing phenothiazines exposed to laser radiation with materials surfaces, in view of biomedical applications

Phenothiazine drugs - chlorpromazine (CPZ), promazine (PZ) and promethazine (PMZ) - were exposed to 266 nm (fourth harmonic of the Nd:YAG pulsed laser radiation) in order to be modified at molecular level and to produce an enhancement of their antibacterial activity. The irradiated samples were analysed by several methods: pH and surface tension measurements, UV-vis-NIR absorption spectroscopy, laser induced fluorescence and thin layer chromatography. The purpose of these investigations was to study and describe the modified properties of the medicines to further investigate their specific interactions with materials such as cotton, polyester and Parafilm M as a model smooth surface. The textile materials may be impregnated with phenothiazines drug solutions exposed to laser radiation in order to be used in treatments applied on the surface of the organism. Some of the phenothiazines solutions exposed prolonged time intervals to laser radiation have much better activity against several bacteria. Therefore, in the paper, it is reported the wetting behaviour of CPZ, PZ and PMZ solutions, irradiated for time intervals between 1 and 240 min, on the surfaces of the three textures in order to draw a conclusion about their wettability as a function of time.

Time survivor study of Escherichia coli with polyhexamethylene biguanide on cotton

Time survivor or time kill studies are commonly used to investigate the efficacy of antimicrobial agents in homogeneous solutions. Such a study was attempted via a textile treated with an antimicrobial agent. For this study, a finished undyed cotton fabric and a commercially available antimicrobial agent, polyhexamethylene biguanide, were used. The release of the antimicrobial agent from the cotton fabric when submerged in water with a liquor-to-cloth ratio of 20:1 was evaluated. The antibacterial agent-treated cotton fabric was also tested according to the JIS L 1902 absorption antibacterial testing method at various agent concentrations applied to the fabric and incubation times. The treated textile showed a quick release of agent when submerged in water and the results of the antibacterial tests showed increasing antibacterial activity with increases in concentration, as has been found in homogeneous solutions. Fabrics treated with lower concentrations of the agent show bacteriostatic action. A regrowth of microorganisms was additionally noted at certain incubation times.

Stability of colloidal silver nanoparticles trapped in lipid bilayer: effect of lecithin concentration and applied temperature.

The use of silver nanoparticle on various substrates has been widespread because of its good antibacterial properties that directly depend on the stability of the silver nanoparticles in a colloidal suspension. In this study, the colloidal solutions of the silver nanoparticles were synthesised by a simple and safe method by using lecithin as a stabilising agent and their stability was examined at various temperatures. The effect of the lecithin concentrations on the stability of the synthesised silver nanoparticles was examined from 25 to 80°C at 5°C intervals, by recording the changes in the UV-vis absorption spectra, the hydrodynamic diameter and the light scattering intensity of the silver nanoparticles. In addition, the morphology of the synthesised silver nanoparticles was investigated with the low-voltage scanning electron microscopy and transmission electron microscopy. The results indicated that increasing temperature caused different changes in the size of the stabilised and the unstabilised silver nanoparticles. The size of the stabilised silver nanoparticles reduced from 38 to 36 nm during increasing temperature, which confirmed good stability.