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¹H NMR spectrum of NY in a DMSO-d6 and b D2O, showing the presence of two cis- and trans-diazo isomers in deuterated water (500 MHz, 298 K; * = protons belonging to minor cis-diazo species)
Source publication
In this paper, the bifunctional monomer glycidyl methacrylate (GMA) was employed in a simple two-step synthetic strategy with the aim of developing a Nitrazine Yellow-based pH-meter wearable sensor. The catalyzed epoxy ring-opening of GMA allowed the formation of a covalent bond with the sulfonate groups of the halochromic dyestuff, while potassium...
Citations
... Poly(glycidyl methacrylate) possesses a strained epoxy ring that is susceptible to nucleophilic reaction, enabling the ring opening by a wide range of nucleophiles, [29] which provides a way to introduce functional groups to side groups of polymer chain. Due to this property, GMA is extensively utilized and studied as a fundamental component in copolymers, [30,31] coatings, [32,33] as a compatibilizer [34] and in absorbing systems [35]. Similar trends are observed in nanoscale applications, particularly in the polymer brushes [36,37] and nanocomposite systems [38]. ...
In this paper, we present a facile method of synthesis and modification of poly(glycidyl methacrylate) brushes with 6-aminofluorescein (6AF) molecules. Polymer brushes were obtained using surface-grafted atom transfer radical polymerization (SI-ATRP) and functionalized in the presence of triethylamine (TEA) acting both as a reaction catalyst and an agent preventing aggregation of chromophores. Atomic force microscopy (AFM), FTIR, X-ray photoelectron spectroscopy (XPS) were used to study the structure and formation of obtained photoactive platforms. UV/Vis absorption and emission spectroscopy and confocal microscopy were conducted to investigate photoactivity of chromophores within the macromolecular matrix. Owing to the simplicity of fabrication and good ordering of the chromophore in a thin nanometric layer, the proposed method may open new opportunities for obtaining light sensors, photovoltaic devices, or other light-harvesting systems.
... Consequently, there are many alternatives for the formulation and application of sol-gel coatings in the field of textile functionalization, as choosing the correct and opportune functional silane precursor, which allows for the desired chemical and physical properties improvement of the fabric. Because of the moderate processing conditions required and the use of ordinary commercial textile finishing machines, in recent years, there has been a surge in interest in the application of the sol-gel approach to produce functional coated textiles [35][36][37][38][39], for example water-repellent fabrics. In general, surfaces that exhibit water contact angles > 150° (on which water drops remain almost spherical and easily roll off, also able to remove dirt particles in their path), are usually called superhydrophobic surfaces [40,41]. ...
... Consequently, there are many alternatives for the formulation and application of sol-gel coatings in the field of textile functionalization, as choosing the correct and opportune functional silane precursor, which allows for the desired chemical and physical properties improvement of the fabric. Because of the moderate processing conditions required and the use of ordinary commercial textile finishing machines, in recent years, there has been a surge in interest in the application of the sol-gel approach to produce functional coated textiles [35][36][37][38][39], for example waterrepellent fabrics. In general, surfaces that exhibit water contact angles > 150 • (on which water drops remain almost spherical and easily roll off, also able to remove dirt particles in their path), are usually called superhydrophobic surfaces [40,41]. ...
The textile-finishing industry, is one of the main sources of persistent organic pollutants in water; in this regard, it is necessary to develop and employ new sustainable approaches for fabric finishing and treatment. This research study shows the development of an efficient and eco-friendly procedure to form highly hydrophobic surfaces on cotton fabrics using different modified silica sols. In particular, the formation of highly hydrophobic surfaces on cotton fabrics was studied by using a two-step treatment procedure, i.e., first applying a hybrid silica sol obtained by hydrolysis and subsequent condensation of (3-Glycidyloxypropyl)trimethoxy silane with different alkyl(trialkoxy)silane under acid conditions, and then applying hydrolyzed hexadecyltrimethoxysilane on the treated fabrics to further improve the fabrics’ hydrophobicity. The treated cotton fabrics showed excellent water repellency with a water contact angle above 150° under optimum treatment conditions. The cooperative action of rough surface structure due to the silica sol nanoparticles and the low surface energy caused by long-chain alkyl(trialkoxy)silane in the nanocomposite coating, combined with the expected roughness on microscale due to the fabrics and fiber structure, provided the treated cotton fabrics with excellent, almost super, hydrophobicity and water-based stain resistance in an eco-sustainable way.
... Recently, a simple strategy for preparing new stimuli-responsive cellulosic fabrics through the chemical modification of cellulose has been reported [240]. Although the grafting of acrylate monomers onto cellulose has already been extensively reported under heterogeneous conditions, the thermal-induced grafting of glycidyl methacrylate as a crosslinker of a pH-sensing dyestuff onto cellulose has been reported for the first time in the literature. ...
... It is harmful and can cause life-threatening diseases and skin irritation [128]. [240] In a second step, after the addition of water, the hybrid network was formed through hydrolysis and condensation reactions. The sol-gel solution was applied to polyamide (PA) and cotton (CO), and the sol-gel technique and conventional dyeing were compared in terms of washing fastness. ...
In recent years thanks to the Internet of Things (IoT), the demand for the development of miniaturized and wearable sensors has skyrocketed. Among them, novel sensors for wearable medical devices are mostly needed. The aim of this review is to summarize the advancements in this field from current points of view, focusing on sensors embedded into textile fabrics. Indeed, they are portable, lightweight, and the best candidates for monitoring biometric parameters. The possibility of integrating chemical sensors into textiles has opened new markets in smart clothing. Many examples of these systems are represented by color-changing materials due to their capability of altering optical properties, including absorption, reflectance, and scattering, in response to different external stimuli (temperature, humidity, pH, or chemicals). With the goal of smart health monitoring, nanosized sol–gel precursors, bringing coupling agents into their chemical structure, were used to modify halochromic dyestuffs, both minimizing leaching from the treated surfaces and increasing photostability for the development of stimuli-responsive sensors. The literature about the sensing properties of functionalized halochromic azo dyestuffs applied to textile fabrics is reviewed to understand their potential for achieving remote monitoring of health parameters. Finally, challenges and future perspectives are discussed to envisage the developed strategies for the next generation of functionalized halochromic dyestuffs with biocompatible and real-time stimuli-responsive capabilities.
... As a result, widespread research and development have been carried out, making them an indispensable part of an emerging new technology field. Among others, pH-sensitive wearable devices are currently attracting interest in several areas of fundamental and applied research with the goal of detecting acidic or alkaline values for real-time monitoring applications in healthcare [7][8][9]. Indeed, wearable chemical sensors may be used to provide valuable information about wearers' health, monitoring them during their daily routine. ...
In the field of stimuli-responsive materials, introducing a pH-sensitive dyestuff onto textile fabrics is a promising approach for the development of wearable sensors. In this paper, the alizarin red S dyestuff bonded with a sol-gel precursor, namely trimethoxy-[3-(oxiran-2-ylmethoxy)propyl]silane, was used to functionalize polyethylene terephthalate fabrics, a semi-crystalline thermoplastic polyester largely used in the healthcare sector mainly due to its advantages, including mechanical strength, biocompatibility and resistance against abrasion and chemicals. The obtained hybrid halochromic silane-based coating on polyester fabrics was investigated with several chemical characterization techniques. Fourier transform infrared spectroscopy and X-ray Photoelectron Spectroscopy confirmed the immobilization of the dyestuff-based silane matrix onto polyethylene terephthalate samples through self-condensation of hydrolyzed silanols under the curing process. The reversibility and repeatability of pH-sensing properties of treated polyester fabrics in the pH range 2.0–8.0 were confirmed with diffuse reflectance and CIELAB color space characterizations. Polyester fabric functionalized with halochromic silane-based coating shows the durability of halochromic properties conversely to fabric treated with plain alizarin red S, thus highlighting the potentiality of the sol-gel approach in developing durable halochromic coating on synthetic substrates. The developed wearable pH-meter device could find applications as a non-invasive pH sensor for wellness and healthcare fields.
... As an attractive application, textile surfaces treated by sol-gel coatings containing halochromic dyestuffs can be used as pH probes for wearable sensors in continuous contact with the skin also thanks to the no-cytotoxic effects of sol-gel matrix [43][44][45]. Thus, they can be employed for continuous, non-invasive monitoring of human sweat's pH, providing information for assessing human performance, health, and well-being [46,47]. ...
... Moreover, the methinic H 5 and the methylenic H 6 protons of the GPTMS epoxy ring resolve in a low-field shift due to the formation of an ether linkage with the sulphonate end of the ARS dyestuff, as shown in Fig. 1c and 1d in the aliphatic region of the 1 H NMR spectra. These findings confirm sulfonate groups' efficacy as a nucleophilic substituent in the epoxide ring-opening reaction of the GPTMS precursor, as previously demonstrated in other experimental research [45,67]. ...
... Indeed, CO_GPTMS-ARS revealed a durable coating after 5 washing cycles, although the ini-tial weight loss (1.06 %) remained unchanged after subsequent laundry cycles. Furthermore, compared to a previous study investigating the radical grafting of glycidyl methacrylatefunctionalized nitrazine yellow on cotton fabrics, leaching around 4% of the coating after the first washing cycle [45], the adhesion of the sol-gel functionalized halochromic dyestuff on cellulose surfaces proved to be more effective. This comparison confirms the relevance of the sol-gel technique in the production of colloids adequately participating in the SiAOAC bond formation with cellulose substrates. ...
Hypothesis
The broad detection properties of alizarin, not only concerning pH variations but also temperature, glucose and health-like relevant cations alterations, make it a molecule of great scientific interest, particularly for developing multifunctional wearable sensors.
Experiment
Herein, the alizarin red S dyestuff is bonded with trimethoxy-[3-(oxiran-2-ylmethoxy)propyl]silane, as a sol-gel precursor, to functionalize cotton fabrics. The chemical and structural properties of both plain and silane-functionalized dyestuffs are investigated in solution and solid-state by several chemical-physical characterization techniques.
Findings
The hybrid dyestuff characterization reveals the epoxy ring-opening of the silica precursor, leading to covalent linkages to the sulfonic group of alizarin, which retains its structure during the sol-gel reaction. The silane-functionalized halochromic dyestuff shows similar halochromic behaviour as its pristine solution in the investigated pH range, thus demonstrating a color shift from yellow to red due to the protonation/deprotonation reversible mechanism of the chromophore. The reversibility and repeatability of pH-sensing properties of treated cotton fabrics are confirmed by diffuse reflectance and CIELAB color space characterizations. Cotton fabric functionalized with alizarin-containing sol-gel coating shows excellent durability of halochromic properties, thus emerging as a versatile platform for stimuli-responsive materials.
... 9 In this context, there is an urgent requirement for simple, rapid, and economical methods to identify the toxic contaminants and to combat the infecting microorganisms. 10 With the changing scenario, the transmission of infectious diseases is no more constrained to the waterborne route. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has exemplified the spread of contamination facilitated by mostly touch surfaces. ...
... 13 −15 In one study, glycidyl methacrylate was applied as a coating onto cotton fabric to develop smart textiles with wearable pH sensors. 10 Another study was reported on fiber-based piezoelectric and triboelectric sensors for flexible and wearable electronics for applications in artificial intelligence. 16 To achieve real-time monitoring, wearable sensors have emerged in the field of diagnostic tools for the detection of environmental contaminants. ...
... Several methods have been reported to prepare halochromic textiles, including conventional dyeing techniques [28,29] and coating indicator dyes [30][31][32] onto textile surfaces. Nonetheless, integrated sensory technology into textiles remains a significant challenge since function textile materials are strongly restricted by washability and durability, making research and development extremely difficult [18,33]. ...
The wearable textile sensors have emerged as a powerful and convenient tool in real-time monitoring yet are always constrained by the limited sensitivity, washability, and durability in practical applications. In this work, a stable, reusable, and rapid response pH-responsive smart cotton textile was successfully prepared by immobilizing a naphthalimide-rhodamine (NR) probe onto cotton. This smart textile was prepared through a simple two-step process involving a silylation and a novel aromatic nucleophilic substitution. Moreover, this method could be easily extended to coupling various naphthalimide-based indicator dyes to the hydroxyl-containing materials and thus provided a rational and general strategy for designing smart sensing textile sensors. Attractively, the resultant textile exhibited outstanding sensing performance include a rapid response-time (< 1 s), elxcellent color stability (~24 h), transcendent reusability (~20 recovery cycles), and reliable washing resistance (~40 washing cycles). It is expected to further exploit their applications in smart textile sensors, food packaging, and wound dressing.
... The latter can attack the double bond of the bifunctional GMA monomer whose epoxy ring group was previously catalytically opened for the covalent functionalization of the NY. A similar approach was performed by Trovato et al. [35] with a radical procedure designed to promote the in situ thermal-induced grafting of the GMA-functionalized NY. In this research, potassium persulfate (KPS) was used as a free-radical initiator able to dissociate giving potassium and persulfate ions under thermal heating [36]. ...
This review presents current literature on different nanocomposite coatings and surface finishing for textiles, and in particular this study has focused on smart materials, drug-delivery systems, industrial, antifouling and nano/ultrafiltration membrane coatings. Each of these nanostructured coatings shows interesting properties for different fields of application. In this review, particular attention is paid to the synthesis and the consequent physico-chemical characteristics of each coating and, therefore, to the different parameters that influence the substrate deposition process. Several techniques used in the characterization of these surface finishing coatings were also described. In this review the sol–gel method for preparing stimuli-responsive coatings as smart sensor materials is described; polymers and nanoparticles sensitive to pH, temperature, phase, light and biomolecules are also treated; nanomaterials based on phosphorus, borates, hydroxy carbonates and silicones are used and described as flame-retardant coatings; organic/inorganic hybrid sol–gel coatings for industrial applications are illustrated; carbon nanotubes, metallic oxides and polymers are employed for nano/ultrafiltration membranes and antifouling coatings. Research institutes and industries have collaborated in the advancement of nanotechnology by optimizing conversion processes of conventional materials into coatings with new functionalities for intelligent applications.
... The latter can attack the double bond of the bifunctional GMA monomer whose epoxy ring group was previously catalytically opened for the covalent functionalization of the NY. A similar approach was performed by Trovato et al. [35] with a radical procedure designed to promote the in situ thermal-induced grafting of the GMA-functionalized NY. In this research, potassium persulfate (KPS) was used as a free-radical initiator able to dissociate giving potassium and persulfate ions under thermal heating [36]. ...
This review presents current literature on different nanocomposites coatings and surface finishing for different substrates (such as textiles, concrete, plastics, stones, metals and so on). In particular, this study is focused on smart materials, drug delivery systems, and industrial, antifouling and nano/ultrafiltration membrane coatings. Each of these nanostructured coatings shows interesting properties for different fields of application. In this review, particular attention is paid to the synthesis and the consequent physico-chemical characteristics of each coating and, therefore, to the different parameters that influence the substrate deposition process. Several techniques used in the characterization of these surface finishing coatings are also described. In this review, the sol-gel and polymerization method for preparing stimuli-responsive coatings as smart sensor materials is described; functional polymers and nanoparticles sensitive to pH, temperature, phase, light and biomolecules are also treated. Finally, nanomaterials based on phosphorus, borates, hydroxy carbonates and silicones are used and described as flame retardant coatings; organic/inorganic hybrid sol-gel coatings for industrial applications are illustrated, together with functional nanofiller (carbon nanotubes, metallic oxides, etc.) and polymers employed for nano/ultrafiltration membrane and antifouling coatings. In the last decades, several research institutes and industries have collaborated for the advancement of nanotechnology by optimizing conversion processes of conventional materials into coatings with new functionalities for intelligent, innovative, eco-sustainable and advanced applications.
Cotton and other cellulose fibres are preferred in the production of comfortable smart clothing due to their softness, moderate strength, shape adaptability, moisture absorbency, and moisture vapour transmission properties, which are well suited for the human body compared to synthetic fibres. These fibres offer enhanced thermo-psychological and tactical comfort. Cotton's sheen diminishes when spun into yarn due to the uneven surface formed by combining fibres. Despite its tendency to wrinkle, limited dimensional stability, and poor dye absorbency, cotton's widespread availability makes it a popular choice for comfortable, smart clothing. Modifications can further improve the comfort of these fibres. Smart textiles, incorporating sensors and instruments for information management, are renowned in textile research. However, the presence of smart materials in clothing may reduce its comfort properties. Smart clothing made from cotton and cellulose materials provides superior comfort compared to other natural and synthetic fibres.
