This study developed sensory polymeric materials for the colorimetric sensing of TNT in aqueous media. Solid films and coated fabrics permitted the detection of TNT, through colour change, and its ...quantification, by taking a picture of the materials and processing their RGB parameters to define the evolved colour.
We prepare low density nanoporous aramid films reinforced with carbon-based nanocharges (graphene, carbon nanofibers and carbon nanotubes), using ionic liquids to generate and control the porous ...structure, reaching a density reduction of about 4 times and pore sizes down to 240 nm. Because of the low dispersion ability of the nanocharges in the aramid matrix, we carried out a novel functionalization process in which nanocharges were chemically modified by anchoring a polyamide model to their surface. Then, we tested the different behavior of the aramid films reinforced with neat and functionalized nanocharges, observing that functionalization led to better nanocharges dispersion, reduction of pore size from the micrometer to the nanometer range and the improvement of the mechanical behavior, resulting in higher relative Young's moduli values (around 60% higher in porous aramids reinforced with functionalized nanocharges).
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•Nanoporous reinforced aramids have been produced using ionic liquids.•Carbon-based nanocharges were used as matrix reinforcements.•A novel functionalization process improved the dispersion of the nanocharges.•Pore sizes of 250 nm and relative Young's moduli values of 2.3 GPa (g cm−3)−1 were obtained.
We prepared high-performance aromatic copolyamides, containing bithiazole and thiazolo-thiazole groups in their main chain, from aromatic diamines and isophthaloyl chloride, to further improve the ...prominent thermal behavior and exceptional mechanical properties of commercial aramid fibers. The introduction of these groups leads to aramids with improved strength and moduli compared to commercial meta-oriented aromatic polyamides, together with an increase of their thermal performance. Moreover, their solubility, water uptake, and optical properties were evaluated in this work.
We have developed a new sensory material for the rapid and inexpensive determination of Zn(II), and we have carried out a proof of concept for the determination of Zn(II) in biological samples. The ...interaction with Zn(II) generates an OFF-ON fluorescence process on the material, which can be recorded both with a fluorimeter and with a smartphone by analyzing the RGB components of the taken photographs. This sensory material is prepared with 99.75% of commercially available monomers and contains 0.25% of a sensory monomer based on a quinoline structure. The sensory motifs are chemically anchored to the polymeric structure, and, accordingly, no migration of organic substances from the material occurs during the sensing process. Our method has been tested with freshly prepared Zn(II) aqueous solutions, but also with biological samples from exudates of chronic wounds. The proposed methodology provides limits of detection (LOD) of 13 and 27 ppb when employing a water-soluble polymer (WsP) and a hydrophilic polymeric film (HP), respectively, using emission spectroscopy. The measurements have been contrasted with ICP-MS as the reference method, obtaining reliable data. This study is the starting point toward a larger investigation with patients, which will address the challenge of establishing a direct relationship between the concentration of zinc(II), other cations and also of amino acids, with the protease activity and, finally, with the state/evolution of chronic wounds. In this context, the proposed sensory material and others we are now working with will act as a simple and cheap method for this purpose.
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•Sensory materials increase their fluorescence in presence of zinc (II) in biological media.•The sensory materials are polymers with chemically anchored sensory motifs.•The sensory materials are crosslinked polymer films and also water-soluble polymers.•As a proof of concept, the Zn(II) content of a human chronic wound was estimated.
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•Microcellular aramid films have been obtained using exclusively ionic liquids.•Density has been diminished from 1.4 g⋅cm−3 down to 0.37 g⋅cm−3.•Average cell size lies in the ...microcellular range (between 1 and 8 μm).•Cellular morphology can be controlled through the ionic liquid proportion.•Thermally induced phase-separation process has been investigated.
We prepared microporous aramid films through a simple, inexpensive and green way, using ionic liquids (IL) as porosity promoters. Commercial poly(m-phenylene isophthalamide) (MPIA) films with different IL proportions were prepared, and then microporous films were obtained by removing the IL in distilled water. Microporous films presented density values between 0.34 and 0.71 g⋅cm−3 (around five times lower to commercial MPIA), with a homogeneous and controlled cellular morphology dependent on the proportion of the IL, showing cell sizes in the microcellular range (radii between 1 and 8 µm). Thermal, mechanical and electrical properties (specifically ionic conductivity) of the aramid films were analyzed to evaluate the influence of the IL proportion. Finally, it was observed that the MPIA/IL system presented a reversible thermally induced phase-separation process around 60 °C, which was characterized through AFM-Raman images and spectra, together with the variation of the ionic conductivity.
This paper describes a strategy followed to achieve a sensing phenomenon in aqueous media using water-insoluble organic molecules. A sensory polymeric material for the colorimetric sensing of cyanide ...in water has been developed based on the reactivity of this anion with a fluorene derivative.
Microcellular sensory polymers prepared from solid sensory polymeric films were tested in an aqueous Hg(II) detection process to analyze their sensory behavior. First, solid acrylic-based polymeric ...films of 100 µm thickness were obtained via radical copolymerization process. Secondly, dithizone sensoring motifs were anchored in a simple five-step route, obtaining handleable colorimetric sensory films. To create the microporous structure, films were foamed in a ScCO₂ batch process, carried out at 350 bar and 60 °C, resulting in homogeneous morphologies with cell sizes around 5 µm. The comparative behavior of the solid and foamed sensory films was tested in the detection of mercury in pure water media at 2.2 pH, resulting in a reduction of the response time (RT) around 25% and limits of detection and quantification (LOD and LOQ) four times lower when using foamed films, due to the increase of the specific surface associated to the microcellular structure.
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•We have produced microcellular aramid films using ionic liquids and ScCO2.•Density has been diminished from 1.4 g cm−3 down to 0.3 g cm3.•Thermal degradation of microcellular aramids ...begins around 400 °C.•Relative Young’s moduli values are higher than 1.2 GPa (g cm−3)−1.
We have deeply diminished the density of high performance aromatic polyamides or aramids. Thus, we have prepared microcellular films that at the same time maintain the outstanding thermal and mechanical properties characteristic of these high performance materials. Two different cellular aramids were produced, based on commercial poly(m-phenylene isophthalamide), one of them with an additional azide group. Microcellular structures have been obtained by adding ionic liquids combined to ScCO2 foaming process, with cell sizes between 0.6 and 4.7 µm and cell densities between 109 and 1011 cells cm3. The density was lowered for the commercial poly(m-phenylene isophthalamide) (Nomex® and Teijin Conex®) from 1.43 to 0.62 g cm−3 and from 1.48 to 0.31 g cm3 for the aramid containing the azide group. Foams present the following thermal and mechanical properties: 5% weight loss observed at T > 400 °C and relative Young modulus and tensile strength of 1.2 GPa (g cm−3)−1 and 60 MPa (g cm−3)−1, respectively.
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•Sensory polymeric materials change their colour in presence of oxidant atmospheres.•The sensory materials are films shaped with embedded aniline.•The detection and quantification are ...based both on optical and electrical methods.•The detection is achieved visually and also using conventional and simple devices.•The presence of oxidants Cl2 and H2O2 in air is detected in the ppbv range.
Conventional nonconductive vinylic films with dispersed aniline change their color and become conductive in the presence of specific oxidant gases, namely, chlorine and hydrogen peroxide. The color change arises from the polymerization of the aniline to yield the conjugated polymer polyaniline, which at the same time renders the flexible vinylic films conductive. We present a simple and straightforward method using both colorimetric and electrical responses to detect and quantify the presence of oxidants (Cl2 and H2O2) in the air. Using RGB analysis (red, green and blue parameters defining the colors in digital pictures on a computer display) based on different pictures taken with a smartphone of discs extracted from the films and by measuring the UV–vis spectral variation in the presence of different concentrations of Cl2 and H2O2, we obtained limits of detection and quantification between 15 and 200 ppbv for H2O2 and between 37 and 583 ppbv for Cl2. Additionally, the electrical response was measured using a fabricated device to visually detect the electrical conductivity activation of the sensor in the presence of oxidant atmospheres, detecting a rapid decrease in resistivity (three orders of magnitude) when the polymerization of aniline began, changing the film from non-conductive to conductive.
We have developed a new extremely hydrophilic polymeric film suitable for the detection and quantification of chloride in human sweat directly on the skin. The film, or membrane, has chemically ...anchored 6-methoxyquinoline groups as chloride responsive fluorescent motifs. We have prepared the sensory material from a standard vinyl copolymer, by a convenient and easy solid-phase reaction. The sensory material has a water swelling percentage of 700%, facilitating an immediate detection of chloride, is reusable for at least 6 cycles and can be handled without care by unskilled persons. The initially high fluorescence of the material decreases in the presence of chloride, allowing the quantification of chloride concentration by using the colour definition of a digital picture or a fluorimeter. The suitability of the material to perform quantitative chloride analysis of human sweat by putting it in contact with the skin offers promise for its application in the sweat test used for the diagnosis of cystic fibrosis (CF).
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