Jesús L. Pablos

Efficient biodegradation of common ionic liquids by Sphingomonas paucimobilis bacterium

The biodegradation of ionic liquids (ILs) was evaluated by an indirect impedance technique, through which carbon dioxide production was measured during bioassay time. The biodegradation study was focused on finding a microorganism able to efficiently degrade common IL compounds. For the first time, a bacteria strain of Sphingomonas paucimobilis was employed in biodegradability tests of ILs, carried out for 37 commercial imidazolium-, pyridinium-, pyrrolidinium-, ammonium- and phosphonium-based ILs, including in the sample 12 different anions and 14 different cations. Remarkably, more than half of ILs studied (54% of the sample) exhibited a biodegradation percentage ≥60% after a 28-day incubation period with S. paucimobilis at 45 °C; therefore, they behave as easily biodegradable compounds from the indirect impedance test. In summary, current results suggested the possibility of biotreatment for the rapid and ultimate mineralisation of widely used ILs, such as BmimNTf2, BmimPF6, etc., which were noted as recalcitrant to biodegradation in previous standard tests with other microorganisms.

Solid Polymer Substrates and Coated Fibers Containing 2,4,6- Trinitrobenzene Motifs as Smart Labels for the Visual Detection of Biogenic Amine Vapors

Attempts to polymerize trinitrobenzene derivatives (TNB) have been fruitless so far. Accordingly, polymers containing TNB have not been exploited in spite of their envisaged potential applications. Here, we describe two ways for preparing polymers with TNB moieties thus overcoming the previously reported polymerization impairments. We also report on the exploitation of the materials, both obtained as tractable transparent films and coated fibers, as smart labels for the visual detection of amine vapors. More precisely, amines in the atmosphere surrounding the sensory materials diffuse into them reacting with the TNB motifs forming highly colored Meisenheimer complexes, giving rise to development of color and to the naked eye sensing phenomenon. This is the case of highly volatile amines, such as trimethylamine, produced in food spoilage, specifically in the deterioration of fish or meat, for which the color development of the smart labels can be used as a visual test for food freshness.

Solid polymer substrates and smart fibres for the selective visual detection of TNT both in vapour and in aqueous media

This work describes the design of efficient, inexpensive and easily prepared selective sensory polymers with chemically anchored amine groups as 2,4,6-trinitrotoluene (TNT)-sensing motifs as materials for the selective visual detection of TNT in aqueous media and as vapours. The materials are prepared as handleable sensory films or dense membranes from which sensory discs are cut, as well as smart fibres by coating conventional and commercial cotton fabrics. Both types of material exhibited a highly visible colour development from colourless to red upon contact with TNT both in the gas phase and in solution, and the colour change was used to build titration curves using the colour definition parameters of a digital image acquired with a smartphone, i.e., the RGB system. The materials were selective, remaining silent with other nitroaromatic compounds, such as 4-nitrotoluene and 2,4-dinitrotoluene, and the detection limit in solution was close to the micromolar range.

Functional fluorescent aramids: aromatic polyamides containing a dipicolinic acid derivative as luminescent converters and sensory materials for the fluorescence detection and quantification of Cr(VI), Fe(III) and Cu(II)

This work describes the preparation of luminescent, high-performance aromatic polyamides. The fluorescent behaviour was achieved by preparing a diacid monomer containing a fluorescent dipicolinic acid derivative and polymerising it with commercially available aromatic diacid and diamine monomers to give polyisophthalamides. These materials can be structurally compared to commercialised meta-aramid fibres [poly(m-phenylene isophthalamide), brand names: NOMEX® and Teijinconex®]. The pendant fluorescent motif provided the material with a light green fluorescence and was found to be a selective host unit for cations of environmental, biomedical and industrial significance [Cr(VI), Fe(III) and Cu(III)].

Aromatic polyamides and acrylic polymers as solid sensory materials and smart coated fibres for high acidity colorimetric sensing

Reusable colorimetric acid responsive coated fibres and manageable films or membranes have been successfully designed and prepared herein. The design of the materials rely on the preparation of condensation and addition monomers both having the azobenzene group, which is used as a dye moiety and as a weak basic motif, and a N,N-dimethylamino moiety. The N,N-dimethylamino moiety is also used as a weak, albeit stronger, basic group as well as an electron donor or electron withdrawal group, depending on its protonation state. For the sake of applicability, the coated fibres were cotton commodity fabrics, and high-tech aromatic polyamide yarns and fabrics. The high-performance aromatic polyamides and the versatile acrylic structures, along with the pendant weak basic groups, with pKas in water ranging from 1.78 to −0.5 and in air from −1.5 to −3.9, provide the materials with a colorimetric sensing capability over a wide acidity sensing window. This sensing window ranges from 1 × 10−2 to 3 M for perchloric acid in water and from 4 × 10−7 to 9 × 10−2 atm for vapour pressure of hydrogen chloride in air. The colour change of the sensory materials from yellow/blank to red or purple, which occurs upon contact with acidic media, was easily identified using the naked eye. Washing these materials with pure water recovered their original colour and permitted their reuse.

Polymer chemosensors as solid films and coated fibres for extreme acidity colorimetric sensing

We have designed and successfully prepared polymer membranes as manageable films for colorimetric sensor materials for the visual detection of the acidity of water in the low pH range, below 4, and beyond the pH scale, up to a concentration of 11.6 M of perchloric acid. For this purpose, two monomers with weakly basic groups were synthesised, with these monomers containing up to four protonisable groups in the aforementioned acidic regions. The pKa values were calculated for the membranes in water, which exhibited gel behaviour, and ranged between 2.7 and −6.5. Accordingly, visual colour changes qualitatively indicated the acidity of water containing perchloric acid, and the quantification was performed inexpensively by UV/Vis spectroscopy. Titration with other acids is foreseen for practical applications. Moreover, polymer coatings of conventional cotton and high-tech p-aramid fibres, using the designed sensor monomers, yielded smart fabrics, which responded colorimetrically to the acidity of the water media. Furthermore, both membranes and smart fibres exhibited colour changes in air under acidic atmospheres, demonstrating the future development of fully sensory apparels and smart tags with envisaged health and safety applications. In addition, the sensor materials are reusable, because the protonation under acidic conditions is reverted by washing with water, and are highly stable under acidic conditions for long periods of time.

Polycationic scaffolds for Li-ion anion exchange transport in ion gel polyelectrolytes

Ion gel polyelectrolytes (IGPs) were prepared by photopolymerization of the synthetic cationic monomers: 1-(2-methacryloyloxy)ethyl-3-butylimidazolium bis(trifluoromethane sulfonyl)imide (IMMATFSI)/bisfluorosulfonylimide (IMMAFSI) or 1-(2-methacryloyloxy)ethyl-1-methylpyrrolidinium bisfluorosulfonylimide (PYRMAFSI)/bis(trifluoromethane sulfonyl)imide (PYRMATFSI) in the presence of bis(trifluoromethane)sulfonamide (LiTFSI) solutions at different concentrations in either 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), 1-ethyl-3-methylimidazolium bis(trifluorosulfonyl)imide (EMITFSI) or N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (PMPFSI). The resulting IGPs are thermally stable, easy–to-handle solids wherein the overall ionic conductivity ranges from about 1 to about 10 mS cm−1 at 25 °C. The diffusivity of the ions Li, FSI and TFSI was studied at 25 °C by PGSE-NMR. In IGPs containing imidazolium groups both in the polycationic scaffold and the ionic liquid phase, their large Li ion diffusivities (up to 40 × 10−12 m2 s−1, well above that of the anions) suggest the existence of an important contribution of anion exchange Li transport. To a lesser extent anion exchange may also be occurring in IGPs containing pyrrolidinium groups in the polycationic scaffold and imidazolium groups in the ionic liquid phase and to an even lesser extent in those IGPs with pyrrolidinium in both the polyelectrolyte and the ionic liquid phase. Because of the dimensional and thermal stabilities of IGPs, safety of their components, and their large Li-ion diffusivity, these types of electrolytes appear as excellent candidates for Li and Li-ion batteries.

Sensory Polymers for Detecting Explosives and Chemical Warfare Agents

The detection of explosives (EXs) and chemical warfare agents (CWA) is challenging and a topic of current interest. It is driven by societal concerns about the widespread use of explosives in the mining industry and military endeavors and specifically in terrorist attacks and of CWA in the latter. The detection and quantification of these chemicals is twofold, through vapor and in solution detection. Sensory polymers are suitable materials for this purpose because they can be transformed or prepared as intelligent films, coatings, and fibers in sensory materials for transducing devices, as smart strips or tags that can be easily handled, or even as smart coatings for commercial fabrics as well as paint for all kinds of surfaces. The detection is based on any variation of a measurable property arisen from the target species/polymer interaction such as mass uptake, conductivity or resistivity changes, chemo-mechanical and electrochemical behavior variations, and chromogenic and fluorescence behavior modifications.