Emanuela Guido

Hydrophobic behaviour of non-fluorinated sol–gel based cotton and polyester fabric coatings

Water repellency was conferred to cotton and polyester fabrics by an hybrid organic–inorganic finishing obtained by hydrolysis and subsequent condensation of octyltriethoxysilane (OTES) under acidic conditions, in combination with melamine based crosslinking agent N,N,N′,N′,N″,N″-hexakis(methoxymethyl)-1,3,5-triazine-2,4,6-triamine (MF). The application on textile samples was carried out by padding followed by drying and thermal treatment. Water-resistance properties were determined in terms of the contact angle, water uptake and drop adsorption times, whereas the surface composition of treated fabrics was characterized by attenuated total reflectance Fourier transform infrared analyses. Textile fabrics treated with the hybrid OTES–MF sol exhibited the best water-repellent properties, when compared to those treated with OTES or MF finishing alone. In particular, cotton and polyester samples, treated with a 60 g/L MF solution in a 1:4 MF:OTES molar ratio, showed a water contact angle of 130° and 150°, respectively. The high hydrophobicity of the treated fabrics is supposed to be due to the structural and stereochemical properties of the finishing. The presence of the MF triazine ring seems to favour both the improvement of the outward orientation of the OTES alkyl chains, and the crosslinking of N-methylol groups to form a three-dimensional film around the fibres which increases the surface roughness. The contact angle values and the characteristic IR peaks confirmed the presence of the hybrid coating on cotton fabrics even after multiple washing cycles.

Flame Retardant Finishing for Textiles

State of the art and perspectives on chemicals and techniques which have been developed in textile finishing for conferring flame retardant properties to natural and synthetic fibres are discussed in this review. An overview on the mechanism of combustion and fire retardancy is reported as well as the chemistry of flame retardants action, the different available types and their uses. The chemistry of molecules used to improve fire retardancy is discussed along with their thermal stabilities and flame-retardant properties. Simplified assumptions about the gas and condensed phase processes of flaming combustion provide relationships between the chemical structure of polymers and fire behaviour, which can be used to design fire-resistant textile materials. Moreover, an overview of currently accepted test methods on textile fabrics to quantify burning behaviour is reported. Finally, as a consequence of increasing commercial demands in terms of cost-effectiveness coupled with increasing concerns about the environmental and general toxicological character of flame retardant additives, some consideration is also given to both the novel approaches of the chemistry of antimony-free and halogen-free flame retardants and to attempts at increasing the efficiency of known chemistry to enhance char formation by intumescent action.

A wearable sweat pH and body temperature sensor platform for health, fitness and wellness applications

The paper presents the development of a compact system able to measure sweat pH, by means of a functionalized textile and a color sensor, and the skin temperature. The aim is to achieve a wearable miniaturized system capable to estimate the body hydration level during exercise or a heat stress. Potential users span from elderly, first responders to athletes. The system has been characterized in the laboratory by using buffer solution, artificial sweat, and an oven for temperature sensor calibrations. Preliminary on-body trials are also reported in the final part of the paper.

A wearable sensor platform to monitor sweat pH and skin temperature

This work presents a wearable sensing system, aimed to monitor sweat pH and skin temperature in a noninvasive way. The wireless interface and the body coupling via a smart textile make it particularly comfortable and unobtrusive for the wearer; the applications extend from high risks patients hydration monitoring in a home-care environment, to fitness and wellness applications.

Low power textile-based wearable sensor platform for pH and temperature monitoring with wireless battery recharge

Wearable sensing electronics is gradually coming to the foreground, due to the increasing awareness for health, environment and pollution matters. The inclusion of sensors into garments represents one of the most comfortable solutions for the wearer; this can be achieved by associating miniaturized electronics with smart fabrics. Basing our experience on previous studies on pH sensing, a novel smart fabric has been developed as a pH-meter: an organic and atoxic halochromic dye is sol-gel fixed on the textile for durability and reversibility purposes, and the readout is performed with a miniaturized novel sensing platform, including extremely low-power color and temperature sensors, wireless data transmission and a wireless battery recharge system. The potential applications vary from sweat pH monitoring for sport performances or medical research, to measurements of environmental conditions.

Sol-gel 3-glycidoxypropyltriethoxysilane finishing on different fabrics: The role of precursor concentration and catalyst on the textile performances and cytotoxic activity

In this paper, the influence of 3-glycidoxypropyltriethoxysilane (GPTES) based organic-inorganic coatings on the properties of treated textile fabrics was studied. All experimental results were deeply analyzed and thereafter correlated with the employed silica precursor concentration and with the presence of the BF3OEt2 (Boron trifluoride diethyl etherate), used as epoxy ring opening catalyst. SEM analysis, FT-IR spectroscopy, X-ray Photoelectron Spectroscopy (XPS), thermogravimetric analysis (TGA) and washing fastness tests of the sol-gel treated cotton fabric samples were firstly exploited in order to characterize the morphological and structural features of the achieved coatings. Finally, the influence of the resulting nanohybrid coatings was explored in terms of abrasion resistance, tensile strength and elongation properties of treated cotton, polyester and silk fabrics. The catalyst amounts seem to strongly improve the formation of coatings, but still they do not influence the wear resistance of treated textile fabrics to the same extent. Indeed, it was found that increasing catalyst/GPTES ratio leads to a more cross linked inorganic 3D-network. GPTES itself was not found to affect the bulk properties of the selected textile and the resulting coatings were not so rigid to hardly modify the mechanical properties of the treated samples. Finally, it is worth mentioning that in all case the obtained 3-glycidoxypropyltriethoxysilane-based chemical finishing have shown no cytotoxic effects on human skin cells.

Influence of Textile Structure and Silica Based Finishing on Thermal Insulation Properties of Cotton Fabrics

The aim of this work is to investigate the influence of weave structures and silica coatings obtained via sol-gel process on the thermal insulation properties of cotton samples. For this reason three main weave structures (plain, satin, and pique) of cotton fabric were selected with different yarn count, threads per cm, and mass per square meter values. Thereafter, only for the plain weave, the samples were padded using silica sol formed by hydrolysis and subsequent condensation of 3-glycidoxypropyltrimethoxysilane under acidic conditions. The silanized plain weave samples were characterized by TGA and FT-IR techniques. The thermal properties were measured with a home-made apparatus in order to calculate thermal conductivity, resistance, and absorption of all the treated fabric samples. The relationship between the thermal insulation properties of the plain weave fabrics and the concentration of sol solutions has been investigated. Fabrics weave and density were found to strongly influence the thermal properties: pique always shows the lowest values and satin shows the highest values while plain weave lies in between. The thermal properties of treated high-density cotton plain weave fabric were proved to be strongly influenced by finishing agent concentration.

Textile Based Colorimetric pH Sensing: A Platform for Future Wearable pH Monitoring

Wearable electronics is a natural application field of miniaturized sensors, low-power analog and digital devices, microcontrollers and efficient power conversion components, that are able to manage battery power in an optimal way. In the wearable electronics field for biomedical applications, smart textiles are very attractive as sensing devices. They can be fixed with dedicated indicators in order to detect physical quantities which could otherwise be difficult to measure with standard methods. This paper presents the development of a novel platform that using smart textiles, retrieves the information about the pH value by measuring color, which is easily manageable by a readout electronic system. The pH meter consists of a cotton fabric, with a color indicator sol gel fixed on it, in association with an extremely low-power and high-sensitivity electronic system. The device main blocks were fabricated and characterized, with the aim to obtain a wearable sweat pH-meter. The paper discusses the electronic readout innovative features, from the standpoints of performance and sensing properties.