Inkjet Printing of Polypyrrole Electroconductive Layers Based on Direct Inks Freezing and Their Use in Textile Solid-State Supercapacitors.

In this work, we propose a novel method for the preparation of polypyrrole (PPy) layers on textile fabrics using a reactive inkjet printing technique with direct freezing of inks under varying temperature up to -16 °C. It was found that the surface resistance of PPy layers on polypropylene (PP) fabric, used as a standard support, linearly decreased from 6335 Ω/sq. to 792 Ω/sq. with the decrease of polymerization temperature from 23 °C to 0 °C. The lowest surface resistance (584 Ω/sq.) of PPy layer was obtained at -12 °C. The spectroscopic studies showed that the degree of the PPy oxidation as well as its conformation is practically independent of the polymerization temperature. Thus, observed tendences in electrical conductivity were assigned to change in PPy layer morphology, as it is significantly influenced by the reaction temperature: the lower the polymerization temperature the smoother the surface of PPy layer. The as-coated PPy layers on PP textile substrates were further assembled as the electrodes in symmetric all-solid-state supercapacitor devices to access their electrochemical performance. The electrochemical results demonstrate that the symmetric supercapacitor device made with the PPy prepared at -12 °C, showed the highest specific capacitance of 72.3 F/g at a current density of 0.6 A/g, and delivers an energy density of 6.12 Wh/kg with a corresponding power density of 139 W/kg.

Paper Doped with Polyacrylonitrile Fibres Modified with 10,12-Pentacosadiynoic Acid.

This work reports a modification of a fibrous cellulose material (paper) by the addition of polyacrylonitrile (PAN) fibres doped with 10,12-pentacosadiynoic acid (PDA). The fibres are sensitive to ultraviolet (UV) light. When the paper containing PAN-PDA is irradiated with UV light it changes colour to blue as a consequence of interaction of the light with PDA. The colour intensity is related to the absorbed dose, content of PAN-PDA fibres in the paper and the wavelength of UV radiation. The features of the paper are summarised after reflectance spectrophotometry and scanning microscopy analyses. All the properties of the modified paper were tested in accordance with adequate ISO standards. Moreover, a unique method for assessing the unevenness of the paper surface and the quality of printing was proposed by using a Python script (RGBreader) for the analysis of RGB colour channels. The modification applied to the paper can serve as a paper security system. The modified paper can act also as a UV radiation indicator.

NBT-Pluronic F-127 Hydrogels Printed on Flat Textiles as UV Radiation Sensors.

This work reports on the surface-modified woven fabrics for use as UV radiation sensors. The cotton and polyamide fabrics were printed with radiochromic hydrogels using a screen-printing method. The hydrogels used as a printing paste were composed of water, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127) as a gel matrix and nitro blue tetrazolium chloride as a radiation-sensitive compound. The development of the hydrogels' colour occurs after exposure to UV radiation and its intensity increases with increasing absorbed dose. The features of the NBT-Pluronic F-127 radiochromic hydrogels and the fabrics printed with the hydrogels were examined using UV-Vis and reflectance spectrophotometry as well as scanning electron microscopy (SEM). The effects of NBT concentration and UV radiation type (UVA, UVB, UVC) on dose responses of the hydrogels and printed fabrics were also examined. The results obtained reveal that the fabrics printed with NBT-Pluronic F-127 hydrogels can be potentially useful as UV radiation sensors.

Facile and durable antimicrobial finishing of cotton textiles using a silver salt and UV light.

In this study, we present facile antimicrobial finishing of cotton textiles. Screen printing was used for surface-finishing of cotton using a printing paste containing silver nitrate. UVC irradiation was applied to convert silver nitrate into a color product, thus also changing the color of the textiles. The color, its strength and stability of samples, depend on absorbed UVC energy and the formula of the printing paste. Scanning electron microscopy with the energy dispersive X-ray spectrometry revealed formation of silver particles on cotton threads; X-ray diffraction analysis and the time-of-flight secondary ion mass spectrometry did not provide clear information on these products. Microbiological studies revealed that the samples inhibited proliferation of Escherichia coli, Bacillus subtilis and Staphylococcus aureus. Washing fastness tests confirmed resistance of the samples to at least 50 washings. Additionally, the inhibition zones increased as the number of washing cycles increased, which is unique for such samples. This work also presents an approach to the design of antimicrobially finished workwear.