Enhanced colour, hydrophobicity, UV radiation absorption and antistatic properties of wool fabric multi-functionalised with silver nanoparticles

Colour and surface functional properties of wool fabrics coated with gallnut, feijoa skin, and mango seed kernel tannin-stabilised Ag nanoparticles

In the textile industry, textile materials are dyed and multi-functionalised by multi-step treatments that considerably increase the environmental impacts by increasing water and energy usage along with increasing the generation of volume of effluent. In this work, Ag nanoparticles (Ag NPs) were in situ formed and stabilised with gallnut, feijoa fruit skin, and mango seed kernel-derived tannins, and wool fabrics were coated simultaneously with these Ag NPs in the same bath. The Ag NP treatment produced dark to light olive-brown shades on wool fabrics. The treatment conditions for the treatment with Ag NPs were optimised to achieve the best results. The colour intensity, UV radiation absorption, antibacterial activity, surface electrical resistance, and durability of the treatment to washing were assessed by various methods. The gallnut-derived tannin (GNT)-stabilised Ag NP-coated wool fabrics showed overall the best results including excellent antibacterial activity against various types of bacteria. The treatment was durable to at least 20 cycles of IWS 7A washes (equivalent to 80 domestic washes). For the 0.5% Ag NPs on the weight of fibre (owf) dosage, the UV light transmission through the trisodium citrate-stabilised Ag NP-coated fabric at 365 and 311 nm was 6.37 and 0.95% respectively, which reduced to 1.63 and 0.20% for the fabric coated with GNT-stabilised Ag NPs providing excellent protection against UV radiation. The surface resistivity of wool fabric reduced from 1.1 × 1012 ohm cm-1 for the untreated fabric to 1.1 × 109 ohm cm-1 for the fabric coated with 2.0% owf GNT-stabilised Ag NPs. The stabilisation of Ag NPs with GNT prolonged the wash-durability by reducing the leaching of Ag NPs from the treated fabric. The developed method could be a sustainable alternative to traditional multi-stage treatments conducted in the textile industry with toxic synthetic dyes and finishing agents for the colouration and multifunctionalisation of wool fabrics.

The Role of Inorganic Fillers in Electrostatic Discharge Composites

The occurrence of uncontrolled electrostatic discharge (ESD) is among the major causes of damage in unprotected electronic components during industrial processes. To counteract this undesired phenomenon, ESD composites showing static-dissipative and antistatic responses are developed. In particular, static-dissipative materials are able to slow down the flow of electric charges, whereas antistatic materials directly suppress the initial charges induced by undesired charging by properly dispersing conductive fillers within an insulant matrix and thus forming a conductive filler network. In this context, the purpose of this review is to provide a useful resume of the main fundamentals of the technology necessary for facing electrostatic charging. The formation mechanisms of electrostatic charges at the material surface were described, providing a classification of ESD composites and useful characterization methods. Furthermore, we reported a deep analysis of the role of conductive fillers in the formation of filler networks to allow electric charge movements, along with an overview of the different classes of inorganic conductive fillers exploitable in ESD composites, evidencing pros/cons and criticalities of each category of inorganic fillers.

Sparking Nano-Metals on a Surface of Polyethylene Terephthalate and Its Application: Anti-Coronavirus and Anti-Fogging Properties

The nano-metal-treated PET films with anti-virus and anti-fogging ability were developed using sparking nano-metal particles of Ag, Zn, and Ti wires on polyethylene terephthalate (PET) films. Ag nanoparticles were detected on the PET surface, while a continuous aggregate morphology was observed with Zn and Ti sparking. The color of the Ag-PET films changed to brown with increasing repeat sparking times, but not with the Zn-PET and Ti-PET films. The water contact angle of the nano-metal-treated PET films decreased with increasing repeat sparking times. The RT-PCR anti-virus test confirmed the high anti-virus efficiency of the nano-metal-treated PET films due to the fine particle distribution, high polarity, and binding of the nano-metal ions to the coronavirus, which was destroyed by heat after UV irradiation. A highly transparent, anti-fogging, and anti-virus face shield was prepared using the Zn-PET film. Sparking was an effective technique to prepare the alternative anti-virus and anti-fogging films for medical biomaterial applications because of their low cost, convenience, and fast processing.

Shape-controlled silver nanoplates colored fabric with tunable colors, photothermal antibacterial and colorimetric detection of hydrogen sulfide

Anisotropic silver nanoplates are widely anticipated in multifunctional textiles, but their large-scale promotion is limited by the shortcomings of long reaction time, uncontrollable shape and low yield in the preparation process. In this study, a microwave-assisted strategy is provided to prepare shape-controllable silver nanoplates for coloration of non-woven fabric. Anisotropic Ag nanoplates are efficiently coated on the surface of chitosan-pretreated fabric by a simple solution impregnation method, which generates the fabric with tunable color and multiple functions. The Ag nanoplates loaded fabric exhibits excellent photothermal properties at 808 nm laser irradiation due to its unique plasmonic absorption features. Colored fabric shows a strong synergistic antibacterial effect, including silver ion release and hyperthermia caused by the photothermal effect under near-infrared (NIR) light. Additionally, colored fabrics can be used as colorimetric sensors for selective detection of H₂S. The colorimetric values of visible color signal of fabric-based H₂S gas sensor can be real-time precisely detected using a smartphone, enlightening its high potential as a wearable toxic gas alarm device for the simple and rapid detection of hazardous gases.

Recent advances in functionalization of nanotextiles: A strategy to combat harmful microorganisms and emerging pathogens in the 21st century

The textile industry can benefit from nanotechnology as new properties are conferred on functionalized nanotextiles beyond what a fabric can traditionally offer. These properties include extermination of microorganisms by nanotextiles to curtail their growth and dissemination in the environment and in healthcare facilities. The emergence and thriving of multi-drug resistance (MDR) phenomenon among microbes are threats at achieving good health and well-being (goal 3) of sustainable development goals (SDG) of UN. In addition, MDR strains emerge at a higher rate than the frequency of discovery and production of potent antimicrobial drugs. Therefore, there is need for innovative approach to tackle MDR. Among recent innovations is functionalization of textiles with metal nanoparticles to kill microorganisms. This paper explores strategies in nanotextile production to combat emerging diseases in the 21st century. We discussed different nanotextiles with proven antimicrobial activities, and their applications as air filters, sportswear, personal wears, nose masks, health care and medical fabrics. This compendium highlights frontiers of applications of antimicrobial nanotextiles that can extend multidisciplinary research endeavours towards achieving good health and well-being. Until now, there exists no review on exploitation of nanotextiles to combat MDR pathogens as included in this report.

Diatomite encapsulated AgNPs as novel hair dye cosmetics: Preparation, performance, and toxicity

Naturally-occurring diatomite has been successfully utilised as a unique encapsulating material to obtain a highly dispersed suspension of uniformly-sized silver nanoparticles (AgNPs). Plant derived gallic acid was used as the reducing and capping agent. High-resolution scanning and transmission electron microscopy results confirmed the attachment of AgNPs on the surface of diatom frustule and maintained an excellent dispersion stability against particle aggregation. The AgNPs obtained were employed for the colouration of bleached human hair owing to the local surface plasmonic absorption (LSPR) of the AgNPs. The effects of Ag/diatomite concentration, dyeing pH, temperature and time on the produced colour were investigated. Hair fibres treated under optimised conditions display good colour fastness toward solar radiation. The morphology and chemical composition of AgNP-dyed hair were determined by energy-dispersive spectroscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses. The biocompatibility of the Ag/diatomite composite, AgNPs, and the dyebaths were confirmed by in vitro acute dermal and ocular toxicity tests. The diatomite supporting AgNPs therefore hold good promise and enormous potential to be exploited for sustainable dyeing of human hair.

Enhanced insect-resistance, UV protection, and antibacterial and antistatic properties exhibited by wool fabric treated with polyphenols extracted from mango seed kernel and feijoa peel

The synthetic dyes, antimicrobial and insect-resistant agents, UV radiation absorbents, and antistatic agents that are used to introduce multifunctional properties to textiles are not only toxic to the environment but also require multi-step treatments to achieve them. Toxic antimicrobials are responsible for the growth of drug-resistant bacteria. Nature-derived polyphenols, such as tannin, could be a viable green alternative. In this work, wool fabrics were treated with a commercial tannic acid (PP-1), and also with gallotannin-rich polyphenols extracted from feijoa fruit peel (PP-2) and mango seed kernel (PP-3) to introduce multifunctional properties, i.e. to make the fabric antistatic, insect-resistant, hydrophilic, and able to absorb harmful UV radiation. The effect of the treatment on the colour, colour intensity, surface resistivity, UV radiation absorption, antibacterial activity, and insect-repellence was systematically evaluated. It was found that PP-3-treated fabric exhibited excellent surface hydrophilicity, antibacterial activity against Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa, and insect-resistant activity against the larvae of Tineola bisselliella. PP-3 treatment also provided comparable UV protection and antioxidant activity but was marginally inferior to the UV protection and antioxidant activity exhibited by the PP-1-treated fabric. The commercial tannic acid treated fabric provided the best antistatic properties but the lowest surface hydrophilicity. The developed treatment could provide a green and sustainable alternative to hazardous UV absorbing, antibacterial and insect-resistant agents used in the textile industry.

Enhanced thermal stability, hydrophobicity, UV radiation resistance, and antibacterial properties of wool fabric treated with p-aminobenzenesulphonic acid

Wool fibre is a popular fibre for the manufacture of apparel and floor coverings, but it does not have adequate thermal stability, antistatic, UV resistance, and antibacterial properties that are required for some applications, such as outerwear and hospital gowns. In this work, a wool fabric was treated with para-aminobenzenesulphonic acid (ABSA) by the oxidative polymerisation method and its effect on the thermal stability, UV radiation resistance, electrical conductivity and antibacterial properties of the treated fabric was systematically evaluated. It was found that the ABSA treatment had synergistic effects on the various functional properties of the treated fabric. The ABSA treatment not only made the fabric antibacterial but also enhanced its UV radiation absorption capability, surface hydrophobicity, electro-conductivity, tensile strength, and thermal stability. The maximum degradation temperature of the wool fibre increased from 339.5 °C to 349.6 °C and the UV-B transmission through the fabric at 290 nm reduced to 1.5%. The surface hydrophobicity of the treated fabric samples also improved as the surface contact angle of the fabric increased from 119.5° for the untreated to 131.7° for the fabric treated with 4% ABSA. The surface electrical resistance decreased from 1200 × 10⁹ to 484 × 10⁹ Ohm cm⁻¹, and the treated fabric also showed excellent antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae. The developed treatment could be used in the textile industry as an energy-efficient process for the multi-functionalisation of wool and other polyamide fibres.

The treatment with para-aminobenzenesulphonic acid produced a multifunctional wool fabric with enhanced hydrophobicity, thermal stability, UV resistance, and antibacterial properties.