Proyecto de Investigación: OPERACION TECNICA Y EXPLOTACION CIENTIFICA DE DATOS EN RLS DE EXOMARS, Y CONTRIBUCION AL RAX DE MMX
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PID2019-107442RB-C32
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Highly efficient melt polymerization of diaminomaleonitrile
(Elsevier BV, 2021-01-15) Mas, I.; Hortelano, C.; Ruiz Bermejo, Marta; De la Fuente, J. L.; Agencia Estatal de Investigación (AEI); 0000-0002-8059-1335; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
HCN polymers are of great interest in research on the origin of life and, currently, in materials science because they have shown potential for the design of electrical devices, (photo)catalysts and biomedicine. Herein, calorimetric measurements have successfully described the bulk polymerization of HCN tetramer, diaminomaleonitrile (DAMN). Two series of nonisothermal experiments were carried out by differential scanning calorimetry (DSC), and low-heating rate (β) the thermograms (β ≤ 5 °C/min) indicated that the polymerization is initiated at temperatures lower than the DAMN melting point, ~180 °C; while higher heating rates results in a rapid polymerization reaction, which occurs entirely in the liquid phase. The DSC data were analysed using model-free linear iso-conversional methods to estimate kinetic parameters, such as activation energy, and a suitable kinetic model was proposed for these thermal polymerizations in the melt. A preliminary structural and morphological characterization by means of Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) was also completed. This study demonstrated the autocatalytic, highly efficient and straightforward character of this stimulated thermal polymerization of DAMN and, to the best of our knowledge, describes for the first time a systematic and extended kinetic analysis to gain mechanistic insights into this process. The latter was done through the help of simultaneous thermogravimetry (TG)-DSC and in situ mass spectrometry (MS) technique to investigate the gas products generated during these melt polymerizations. These analyses revealed that deamination and dehydrocyanation processes are two relevant reactions involved in DAMN polymerization mechanism.
APTES-Based Silica Nanoparticles as a Potential Modifier for the Selective Sequestration of CO2 Gas Molecules
(Multidisciplinary Digital Publishing Institute, 2021-10-10) Cueto Díaz, Eduardo J.; Valles González, M. P.; Torquemada, M. C.; Gálvez Martínez, Santos; Suárez García, Fabián; Castro Muñiz, Alberto; Mateo Martí, Eva; Agencia Estatal de Investigación (AEI)
In this work, we have described the characterization of hybrid silica nanoparticles of 50 nm size, showing outstanding size homogeneity, a large surface area, and remarkable CO2 sorption/desorption capabilities. A wide battery of techniques was conducted ranging from spectroscopies such as: UV-Vis and IR, to microscopies (SEM, AFM) and CO2 sorption/desorption isotherms, thus with the purpose of the full characterization of the material. The bare SiO2 (50 nm) nanoparticles modified with 3-aminopropyl (triethoxysilane), APTES@SiO2 (50 nm), show a remarkable CO2 sequestration enhancement compared to the pristine material (0.57 vs. 0.80 mmol/g respectively at 50 °C). Furthermore, when comparing them to their 200 nm size counterparts (SiO2 (200 nm) and APTES@SiO2 (200 nm)), there is a marked CO2 capture increment as a consequence of their significantly larger micropore volume (0.25 cm3/g). Additionally, ideal absorbed solution theory (IAST) was conducted to determine the CO2/N2 selectivity at 25 and 50 °C of the four materials of study, which turned out to be >70, being in the range of performance of the most efficient microporous materials reported to date, even surpassing those based on silica.
Catalytic effects over formation of functional thermoplastic elastomers for rocket propellants
(Wiley, 2021-11-22) Lucio, B.; De la Fuente, J. L.; Ministerio de Ciencia e Innovación (MICINN); Instituto Nacional de Técnica Aeroespacial (INTA); Gobierno Vasco
Rheometry was the main method to characterize the curing process of binders made of functional polyurethanes (PUs). The macroglycols characterization by means of additional techniques such as nuclear magnetic resonance, size exclusion chromatography and differential scanning calorimetry, provided further information for the chemorheological description. Materials were based on Butacene ((ferrocenylbutyl)dimethylsilane grafted to hydroxyl-terminated polybutadiene (HTPB)), used in the solid propulsion field. First, the flow parameters for the uncured reactive mixtures of Butacene and four different diisocyanates were analysed via viscometry and these were markedly influenced by the chemical structure of the curing agents. Analysing the rheokinetic constant values of the pre-gel stage for Butacene- and HTPB-reactive systems, relevant catalysis caused by the ferrocene moiety was detected when aliphatic reactants were used, such as isophorone diisocyanate or 1,6-hexamethylene diisocyanate (IPDI and HMDI, respectively). No catalytic effect was found for 2,4-toluene diisocyanate (2,4-TDI) or even for 4,4’-methylenediphenyl diisocyanate (4,4’-MDI). Finally, the use of dynamic rheology was useful to evaluate the critical points during gelation process, where the reactivity of curing agents was associated with the achievement of elastic properties. Both techniques agreed the reactivity order of curing agents with Butacene, which is 4,4’-MDI > HMDI >> 2,4-TDI ≥ IPDI. The knowledge of the structure-reactivity relationship and, moreover, the kinetics of the urethane network formation for these metallo-PUs is paramount in manufacturing processes for advanced thermoplastic elastomer applications.
A dual perspective on the microwave-assisted synthesis of HCN polymers towards the chemical evolution and design of functional materials
(Nature Research Journals, 2020-12-18) Hortal, Lucia; Pérez Fernández, Cristina; De la Fuente, J. L.; Valles González, M. P.; Mateo Martí, Eva; Ruiz Bermejo, Marta; Instituto Nacional de Técnica Aeroespacial (INTA); Agencia Estatal de Investigación (AEI); http://dx.doi.org/10.13039/501100011033; http://dx.doi.org/10.13039/501100010687; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
In this paper, the first study on NH4CN polymerization induced by microwave radiation is described, where a singular kinetic behaviour, especially when this reaction is conducted in the absence of air, is found. As a result, a complex conjugated N-heterocyclic polymer system is obtained, whose properties are very different, and even improved according to morphological features, characterized by their X-ray diffraction patterns and scanning electron microscopy analysis, with respect to those produced under conventional thermal treatment. In addition, a wide variety of relevant bioorganics have been identified, such as amino acids, nucleobases, co-factors, etc., from the synthetized NH4CN polymers. These particular families of polymers are of high interest in the fields of astrobiology and prebiotic chemistry and, more recently, in the development of smart multifunctional materials. From an astrobiological perspective, microwave-driven syntheses may simulate hydrothermal environments, which are considered ideal niches for increasing organic molecular complexity, and eventually as scenarios for an origin of life. From an industrial point of view and for potential applications, a microwave irradiation process leads to a notable decrease in the reaction times, and tune the properties of these new series macromolecular systems. The characteristics found for these materials encourage the development of further systematic research on this alternative HCN polymerization.
Raman spectroscopy coupled to principal component analysis for studying UO2 nuclear fuels with different grain sizes due to the chromia addition
(Elsevier BV, 2021-01-08) Milena Pérez, A.; Bonales, L. J.; Rodríguez Villagra, N.; Fernández Carretero, Sergio; Baonza, V. G.; Cobos, J.; Agencia Estatal de Investigación (AEI); European Research Council (ERC); Milena Pérez, A. [0000-0002-4413-6693]; Baonza, V. G. [0000-0001-9994-0980]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Current necessities of nuclear power plants have led to increase burn-up of the fuel during operation. In this context, some undesirable processes, such as a higher release of gaseous fission products, may occur. New UO2-based fuels are being developed by adding doping agents. Chromia (Cr2O3) has proved to considerably enhance grain growth during sintering, and thus promote the retention of these fission products. The study of these Cr-doped UO2 fuels at in situ conditions would allow testing the real performance of the fuel in operating conditions. The existence of Raman portable instruments makes this scenario feasible. But first, the measurement protocols need to be developed. Therefore, in this paper, we explore the use of Raman spectroscopy as an approach for the analysis of the effect of Cr2O3 addition in a set of UO2single bondCr2O3 sintered pellets. The validity of Raman is demonstrated by using Principal Component Analysis (PCA). Three Principal Components describe 98.8% of the total variance of the data, and they are related to the main Raman modes of the samples. In addition, SEM images have shown the presence of bigger precipitates of Cr2O3 not only when the solubility limit of Cr3+ is exceeded, but also when it is not reached. By XRD, the well-known Vegard behavior is observed, and a solubility limit of Cr3+dissolved into the UO2 matrix is found to be (748±16) ppm for the particular sintering conditions used.
