The fourth issue of 2023 offers six original research articles: surface modification of cotton fabric with quaternized chitosan for wound dressing applications;1 treatment of cotton fabric with antimicrobial silver–copper–zeolite microparticles;2 deposition of polymeric carbide nitrate photocatalyst for solar water splitting;3 modification of micro-arc oxidation (MAO) coating with cerium dioxide particles to improve high-temperature oxidation resistance;4 coating of quartz fiber fabric with alumina particles to enhance their high-temperature mechanical properties and stability;5 and fabrication and testing of drag-reducing paint microstructure.6
Wound dressing fabrics with antibacterial and hemostatic properties are in demand by healthcare and medical industries. In a unique contribution, Wang et al.1 report a synthesis of chitosan-based, ‘comb-like’ zwitterionic polymer surfactant by partial N-alkylation and quaternization, which is then deposited on cotton fabric. Antibacterial efficacy assessment tests show that this novel wound-dressing fabric inactivates and eliminates Escherichia coli and Staphylococcus aureus. In contact with blood, the wound-dressing fabric demonstrates hemocompatibility and shortens the bleeding.
Antimicrobial durable finish of cotton fabrics is also attractive to the commercial textile industry, which produces clothing and sportwear as well as medical textile products for personal protection. In a new contribution,2 an international team of researchers from Bangladesh, China and USA describe the binding of silver–copper–zeolite microparticles to knitted cotton fabrics with acrylic binder and polyurethane resin by using multiple textile industrial coating methods, including padding, nebulizing and printing. The coatings show high antimicrobial performance against S. aureus and Klebsiella pneumoniae bacteria, even after 30 laundry cycles.
In the third contribution to this issue,3 researchers from the Tianjin University in China demonstrate deposition of a high-quality polymeric carbon nitride film, an emerging photoelectrode material for photoelectrochemical cells used in water splitting, on conductive fluorine-doped tin oxide glass using a combination of electrophoretic and vapor deposition methods. The two-step deposition was found to yield higher performance and bonding films over only-electrophoretic deposition in terms of light absorption (lower band gap) and separation/transport of photogenerated charge carriers because of reduced disorder, lower defects and improved crystallinity. The films demonstrate impressive photocurrent density of up to 120 µA/cm2 at 1.23 V.
Titanium alloys with high strength and high-temperature oxidation resistance have been found to have multiple applications in the aviation industry, including space exploration vehicles. However, the alloys oxidize at temperatures above 600°C, limiting their use in high-temperature engines. MAO coatings were recently explored to enhance resistance to high-temperature oxidation of metals. In a new contribution, Chen et al.4 demonstrate that the addition of cerium dioxide to MAO coating improves oxidation resistance of titanium alloys at temperatures as high as 850°C. The researchers found that cerium dioxide particles improve thickness, hardness and adhesion of MAO coatings.
Improvement of material performance at high temperature is also the topic of the contribution by Zhang et al.5 The authors describe deposition of an aluminum oxide ceramic coating on quartz fiber fabric from aluminum sulfate octadecahydrate aqueous solution at 50°C, and subsequent heat treatment. The fabricated quartz fiber fabric with ceramic coating exhibited improved high-temperature mechanical properties. For example, the maximum load that fibers could bear is 2.5 times higher than exhibited by the original fibers. The authors suspect that the aluminum oxide coating suppresses the defects of fibers caused by quartz crystallization at high temperature.
Inspired by designs from nature such as sharkskin, butterfly wings and bird feathers, research laboratories attempt to replicate biomimetic systems and surfaces having a reduced friction with fluids when in motion. In the last contribution to this issue, researchers from the Changchung University of Science and Technology in China describe fabrication of pigeon feather-like microgroove arrays by the laser ablation method.6 The width of microgrooves varied from about 50 to 150 µm, their depth varied from about 7 to 35 µm, whereas the spacing between microgrooves varied from 250 to 400 µm. Aerodynamic testing in a wind tunnel showed up to 6.6–7.2% drag reduction for wind speeds of 27–33 m/s, demonstrating a significant effect of groove spacings on drag reduction. The authors argue that even this small drag reduction could benefit transportation devices, military systems and competitive sports, and contribute to fuel consumption reduction, improved range of transport and/or increased speed.
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