Carbon-paste nanocomposites as unconventional gate electrodes for electrolyte-gated organic field-effect transistors: electrical modulation and bio-sensing

Nanocomposite carbon-paste electrodes (NC-CPEs) have been investigated for the first time in electrolytegated organic field-e¿ect transistors (EGOFETs) as a replacement of conventional metal gate electrodes, using carbon nanotubes (CNTs) as a model carbon filler. Interestingly, the electrical properties of the resulting devices have been modulated by changing the loading percentage of CNTs within the insulating polymeric matrix. The potential of using such non-conventional gate electrodes for sensing purposes has also been evaluated by investigating, as a proof of concept, the formation of a supramolecular complex between a functionalized CNT-based NC-CPE containing ß-cyclodextrin (ß-CD) as a bio-recognition element and tryptophan (TRP). This approach, in synergism with the amplification function of an EGOFET, a¿ords a shift in the threshold voltage (VTH) of the transistor, giving promising analytical results with detection limits at picomolar levels (1.0 ± 0.1 pM) as well as a linear response from 10-12 to 10-9 M. Accordingly, NC-CPEs have been demonstrated to be a potential alternative to metal gate electrodes for the development of a new generation of highly sensitive carbon-based EGOFET bio-sensorsPostprint (published version

Recovery of cellulose from polyester/cotton fabrics making use of ionic liquids

This article refers to the chemical recovery of cellulose from fabrics composed of Cotton (CO)/Polyester (PES) achieved using Ionic Liquids (ILs). Initially, the effect of ionic liquids on the surface of the textile is analyzed, determining the influencing factors related to the entry of IL inside the textile and the chemical mechanism that controls the system. This work considers the influence of the time, ratio, and temperature variables on the system, with the aim of defining which of them has a greater influence on the process. The ability of ionic liquids, specifically 1-Allyl-3-Methylimidazolium Chloride (AmimCl), to dissolve cellulose and subsequently regenerate the material through a simulation of the wet spinning process is evaluated. The responsible for the fiber’s inflation, water or DMSO, has also been another factor of study, analyzing the influence of each solvent and the interactions when in contact with the ionic liquid. Finally, the regenerated substance is characterized by its surface structure using the Scanning Electron Microscope (SEM), its molecular structure by Infrared Spectroscopy Analysis (FTIR), and its thermal stability by Thermogravimetric Analysis (TGA)Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (published version

Functional supramolecular tetrathiafulvalene-based films with mixed valences states

Tetrathiafulvalene molecules substituted with a carboxylic acid group (TTFCOOH) were bound as redox-active moieties into a poly(4-vinyl pyridine) (P4VP) skeleton through non-covalent interactions (hydrogen bonds). The aspect of the resulting P4VP-TTFCOOH films showed a uniform and smooth morphology. Moreover, the redox function of TTFCOOH in P4VP-TTFCOOH was demonstrated using tetrachloroauric acid, iron(III) perchlorate and iodine vapors as doping agents. The oxidized states of TTFCOOH as well as the mixed valance state TTFCOOH0-TTFCOOH+• were generated in a controlled manner in solid state, resulting in an organic film capable of charge transport. The charge transport along the organic donor molecules hydrogen bonded to the polymer matrix was demonstrated employing Electrostatic Force Microscopy (EFM)Postprint (author's final draft

Study of dyeing process of hemp/cotton fabrics by using natural dyes obtained from rubia tinctorum L. and calendula officialis

The objective of this work was to assess the possibility of dyeing a substrate composed of non-textile industrial hemp using natural dyes from common madder (Rubia Tinctorum L.) and calendula (Calendula Officialis) and tannin and alum as mordants. The substrate used for the dyeing had a 25/75 hemp/cotton composition. The hemp raw material is an agricultural by-product that was subjected to mechanical and chemical treatments in order to cottonize the fibers, blend them with cotton, and thus obtain first 40-tex open-end yarns and then a knitted fabric. The latter was subjected to different dyeing conditions by varying the dye, mordant, and method for its application, type of water, and rinsing after dyeing. Measurements of the difference (¿E) and intensity (K/S) of color and fastness to washing and rubbing were carried out. The results showed that dyeing of a non-textile residual hemp substrate is possible, and that calendula is a good option for dyeing it with tap water, tannin-alum set in a meta-mordanting process, and rinsing after 24 h. In this way, a contribution has been made to the circular economy of the textile industry through the use of more sustainable sources and productsThe authors gratefully acknowledge the financial support for this research from the Ministry of Science and Innovation of Spain (Project MAT2016-79352-R) and from the National Secretary of Higher Education, Science, Technology and Innovation of Ecuador (SENESCYT) for Doctoral Fellowship (No. CZ02-000926-2018)Objectius de Desenvolupament Sostenible::8 - Treball Decent i Creixement EconòmicObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraObjectius de Desenvolupament Sostenible::12 - Producció i Consum ResponsablesObjectius de Desenvolupament Sostenible::13 - Acció per al ClimaObjectius de Desenvolupament Sostenible::13 - Acció per al Clima::13.b - Promoure mecanismes per a augmentar la capacitat de planificació i gestió eficaces en relació amb el canvi climàtic als països menys avançats i als petits estats insulars en desenvolupament, centrats concretament en les dones, persones joves i comunitats locals i marginadesPostprint (published version

Supramolecular block copolymers incorporating chiral and achiral chromophores for the bottom-up assembly of nanomaterials

The coordination of the chiral metalloporphyrin ([5,10,15,20-[4-(R,R,R,R)-2-N-octadecylamidoethyloxiphenyl]porphyrin] zinc (II)) and an achiral homologue to an amphiphilic block copolymer of poly(styrene-b-4-vinyl pyridine) (PS-b-P4VP) have been studied in solution and as cast material. The resulting chiral dye-polymer hybrid material has been accomplished via axial coordination between the zinc (II) metal ion in the core of the porphyrin ring and the pyridyl units of the block-copolymer in a non-coordinative solvent. The supramolecular organization and possible chirality transfer to the hybrid material have been studied in solution by UV-visible absorption spectroscopy, fluorescence spectroscopy, Nuclear Magnetic Resonance and Circular Dichroism. The morphology of the chiral and achiral doped polymers has been studied in solid state by Transmission Electron Microscopy and Atomic Force Microscopy. We show that the nanostructures formed depend greatly upon the nature of the side-chains on the porphyrins, where a chiral group leads to a very homogeneous phase-separated material, perhaps indicating that chiral side groups are useful for the preparation of this type of supramolecular hybridPostprint (author's final draft

Advancements in sustainable natural dyes for textile applications: a review

The dyeing and finishing step represents a clear hotspot in the textile supply chain as the wet processing stages require significant amounts of water, energy, and chemicals. In order to tackle environmental issues, natural dyes are gaining attention from researchers as more sustainable alternatives to synthetic ones. This review discusses the topic of natural dyes, providing a description of their main features and differences compared to synthetic dyes, and encompasses a summary of recent research in the field of natural dyes with specific reference to the following areas of sustainable innovation: extraction techniques, the preparation of substrates, the mordanting process, and the dyeing process. The literature review showed that promising new technologies and techniques have been successfully employed to improve the performance and sustainability of natural dyeing processes, but several limitations such as the poor fastness properties of natural dyes, their low affinity with textiles substrates, difficulties in the reproducibility of shades, as well as other factors such as cost-effectiveness considerations, still prevent industry from adopting natural dyes on a larger scale and will require further research in order to expand their use beyond niche applicationsThis work was funded by AGAUR within the OliWasTex project (2021-PROD00074)Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.4 - Per a 2030, modernitzar les infraestructures i reconvertir les indústries perquè siguin sostenibles, usant els recursos amb més eficàcia i promovent l’adopció de tecnologies i processos industrials nets i racionals ambiental­ment, i aconseguint que tots els països adoptin mesures d’acord amb les capacitats respectivesObjectius de Desenvolupament Sostenible::12 - Producció i Consum ResponsablesObjectius de Desenvolupament Sostenible::12 - Producció i Consum Responsables::12.5 - Per a 2030, disminuir de manera substancial la generació de residus mitjançant polítiques de prevenció, reducció, reciclatge i reutilitzacióObjectius de Desenvolupament Sostenible::12 - Producció i Consum Responsables::12.2 - Per a 2030, assolir la gestió sostenible i l’ús eficient dels recursos naturalsObjectius de Desenvolupament Sostenible::12 - Producció i Consum Responsables::12.4 - Per a 2020, aconseguir la gestió ecològicament racional dels productes químics i de tots els residus al llarg del seu cicle de vida, de conformitat amb els marcs internacionals convinguts, i reduir-ne de manera significativa l’alliberament a l’atmosfera, a l’aigua i al sòl a fi de minimitzar-ne els efectes adversos sobre la salut humana i el medi ambientPostprint (published version

PS-b-P4VP block copolymer micelles as a soft template to grow openly porous nickel films for alkaline hydrogen evolution

Highly porous Ni films have been potentiostatically synthesised by micelle-assisted electrodeposition using custom-made PS-b-P4VP block copolymer micelles as a soft template. Two PS-b-P4VP block copolymers with PS/P4VP block ratios of 1:1 and 1:4 were used for the micelle-assisted electrodeposition, resulting in Ni films with large pores of diameters varying from 25 to 600 nm (1:1), and from 10 to 230 nm (1:4). As a result of the interconnected porosity, and hence the drastic increase of the surface-to-volume ratio, the electrocatalytic performance at hydrogen evolution reaction (HER) in alkaline media is significantly improved in comparison to a dense Ni film, and—more importantly—even in comparison to a highly mesoporous Ni film with monodisperse 10 nm wide pores. Most remarkably, it is discovered that the openly porous Ni electrocatalysts not only lead to a simple increase in HER current density, but also to a lower overpotential and a better long-term performance. While the bulk of the films is metallic, Ni(OH)2 is formed on the surfaces of all Ni films during HER. This effect leads to an initial decrease of the catalytic activity, but provides excellent stability in alkaline media. The presented synthesis process for pure Ni may be readily adopted to any other electroplatable metals and alloysThis work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101058076 and the Marie Skłodowska-Curie grant agreement No 764977. Additional funding was obtained from the Generalitat de Catalunya under project 2017-SGR-292 and the Spanish Government under PID2019–108794 GB-I00, PID2020–116844RB-C21, and associated FEDER Project. KE acknowledges the Spanish Ministerio de Uni- versidades for a Margarita Salas fellowship, financed by the European Union – NextGenerationEU. AGC acknowledges financial support from the Spanish Ministry of Science through the “Severo Ochoa” Programme for Centres of Excellence (FUNFUTURE, 2020–2023)Postprint (published version

Amperometric thyroxine sensor using a nanocomposite based on graphene modified with gold nanoparticles carrying a thiolated beta-cyclodextrin

This article reports a novel electrochemical sensor based on a nanocomposite for the sensitive determination of Thyroxine (T4), the active form of the hormone. Hydrodynamic amperometry is performed with a nanocomposite electrode based on the dispersion of a graphene–based filler hybrid-nanomaterial throughout an insulating epoxy resin in the optimum composition ratio (the near–percolation composition). This hybrid-nanomaterial consists of reduced graphene oxide tuned with gold nanoparticles and a biorecognition agent, the thiolated ß-cyclodextrin. Recognition of T4 is accomplished via supramolecular chemistry, due to the formation of an inclusion complex between ß-cyclodextrin and T4. The amperometric device operates at +0.85 V vs. Ag/AgCl, where the oxidation of T4 takes place on the electrode surface. The sensor covers the 1.00 nM to 14 nM T4concentration range in a 0.1 M HCl solution, with a detection limit of 1.00 ± 0.02 nM. The sensor can be easily reset by polishing. It exhibits the lowest detection limit regarding to any other electrochemical electrodes for T4 determination previously described in literaturePostprint (author's final draft

Supramolecular Strategies to Control the Assembly of Organic-Based Materials

[eng] The focus of this thesis is the use of supramolecular chemistry to functionalize polymers to obtain organic-based materials with a control of their structure and properties. The non-covalent functionalization of polymers via supramolecular chemistry is a potentially efficient route to introduce a particular property with which a new functional molecular material can be originated. This strategy has specially been explored to incorporate conjugated structures in polymeric constructs for new semiconducting materials. Although important advances have been made in this field, the incorporation of -electron functional units to polymeric backbones with well-controlled arrangement between the donor and acceptor parts is still an area of huge interest for material science. Following this idea, the supramolecular functionalization of the homopolymer poly(4-vinyl pyridine) (P4VP) with an electron donating unit based on an tetrathiafulvalene (TTF) has been explored. Tetrathiafulvalenes (TTFs) are excellent -electron donor units that are widely studied in molecular electronic applications due to their p-type character and stable doped states. Through complementary hydrogen bonding components of a derivative TTF (TTFCOOH), uniform films incorporating the redox active components have been prepared. When the films were doped using different oxidising agents, Electrostatic Force Microscopy (EFM) studies indicated that a reorganisation at the surface of the films occurred and of charges in their surfaces appeared. Once the application of the P4VP-TTFCOOH films as charge-carrier hybrid material was demonstrated, the next step was to use the block copolymer poly(styrene-b-4-vinyl pyridine) (PS-b-P4VP) due to its amphiphilic behavior. Therefore, different molar ratios of PS and P4VP blocks have been used to prepare new PS-b-P4VP-TTFCOOH thin films. The influence of the phase segregation of the PS-b-P4VP-TTFCOOH film to the charge transportation upon oxidation was performed correlating the Small-Angle X-ray Scattering (SAXS) and EFM results. On the other hand, microfluidics is a microfabrication technique that relies on the manipulation of fluids, which can be used to control the final microstructure and self-assembly of compounds, by the simple adjusting of the values of the hydrodynamic flow focusing (confinement effect). Moreover, microfluidics offers respect to the bulk conditions important advantages such as larger relation surface-to-volume, lower consumption values and a better control of the concentration gradients. The improvement of the intermolecular contact of disk-shaped C3-symmetric tris(TTF) system has been studied using microfluidics. This molecule possesses three bonded derivative TTF units through a central aromatic ring that, under determined conditions, large coiled helical fibers could be obtained by their aggregation. A de-doping process of the C3-symmetric tris(TTF) molecule has been studied using microfluidics, towards the study of the influence of the technique on the organization of this compound. Afterwards, a new characterization methodology was suggested, based on bimodal-Atomic Force Microscopy (bimodal-AFM) in order to draw a distinction between electrostatic and mechanical contributions of the coiled fibers and, corroborating that the charge transportation phenomenon occurred. Furthermore, hydrogels have been in the spotlight due to their biocompatibility in, for instance, tissue engineering applications. Then, the structural enhancement of an ionically-driven coacervated hydrogel obtained via microfluidics platform by tuning flow focusing parameters was studied. In a further step, the functionalization of this hydrogel with TTFCOOH molecules under bulk and microfluidic conditions and its charge-carrier character were also analyzed. Additionally, with the objective to immobilize the hydrogel on surfaces, micro-contact printing, technique was tested. Finally, the organization and phase segregation of the PS-b-P4VP coordinated with a metalloporphyrin system has also been approached. Porphyrins, in general, possess exceptional inherent optical and electronic properties that make them suitable for application related with solar cells. Moreover, due to their electrochemical and photophysic characteristics they can easily be modified with other functional groups. Porphyrins can be found free or complexed with metals and in both states they have self-assembly properties. The coordination between PS-b-P4VP and chiral and an achiral zinc (II) metalloporphyrin has been explored in order to study the chirality transfer from the porphyrin to the hybrid materials. In the last instance, and in an exploratory attempt to use porphyrins as molecular rotors, different strategies of surface immobilization of the porphyrin-block copolymer system were also approached by micro-contact printing