Supercapacitors are an emerging energy storage device that have gained attention because of the large specific power, at a reasonable specific energy, that they exhibit. These energy storage devices could be used alongside of or in the place of traditional electrochemical battery technologies to power reliable electrical devices. The performance of supercapacitorsis largely determined by electrode properties including the surface area to volume ratio, the electrical conductivity, and the ion diffusivity. Nanomaterial synthesis has been proposed as a method of enhancing the performance of many macroscopic supercapacitor electrodes due to the high surface area to volume ratio and unique tunable properties that are often size or thickness dependent for many materials. Specifically, carbon materials (such as carbon nanotubes), metal organic frameworks, (such as ZIF-8), and transition metal dichalcogenides (such as molybdenum disulfide) have been of interest due to their conductivity, large surface area, and ion diffusivity that they exhibit when one or more of their characteristic lengths is on the order of several nanometers.<div><br></div><div>For the experiments, a carbon nanotube-/ZIF-8-/MoS2framework was synthesized into an electrode material. This process involved first dispersing the carbon nanotubes in DMF using ultrasonication and then modifying the structure with polydopamine to create a binding site for the ZIF-8 to attach to the carbon nanotubes. The ZIF-8 was synthesized by combining 1,2,4-Triazole-3-thiol and ZnCl under 120 degrees Celsius. Afterwards, the MoS2was associated with the carbon nanotube and ZIF-8 framework by a disulfide bond with the sulfur vacancy of the MoS2andthe sulfide group of the ZIF-8. Finally, the sample solution was filtered by vacuum filtration and then annealed at 110 degrees Celsius before being deposited on a nickel foam substrate and tested in a 3-electrode electrochemical cyclic voltammetry study.<br></div><div><br></div><div>The resulting materials were found to have a capacitance of 262.15 F/g with corresponding specific energy and specific power values of 52.4Whr/kg and 1572W/kg. Compared to other supercapacitor research materials, this electrode shows a much larger capacitance than other exclusively carbon materials, and comparable capacitance values to the ZIF-8 and MoS2materialswith the added benefits of an easier and faster manufacturing process. Overall, the electrodes developed in this study, could potentially reduce the cost per farad of the supercapacitor to be more competitive energy storage devices<br></div>

Post-combustion CO2 capture is a promising approach for complementing other strategies to mitigate climate change. Liquid absorption is currently used to capture CO2 from post-combustion flue gases. However, the high energy cost required to regenerate the liquid absorbents is a major drawback for this process. As a result, solid sorbents have been investigated extensively in recent years as alternative media to capture CO2 from flue gases. For example, metal organic frameworks (MOFs) are nanoporous materials that have high surface areas, large pore volumes, and flexible designs. A large number of MOFs, however, suffer from 1) low CO2 adsorption capacity at low pressure, which is the typical condition for flue gases, 2) degradation upon exposure to water present in flue gases, and 3) low selectivity of CO2 when present in a mixture of gases. Zeolitic Imidazolate Frameworks (ZIFs) are heavily investigated MOFs for CO2 sorption applications because they have better selectivity for CO2 compared to other MOFs and are resistant to degradation in water due to their hydrophobic nature. However, ZIFs (e.g., ZIF-8) investigated for CO2 sorption applications are typically produced using toxic solvents and their CO2 sorption capacity is drastically lower than other types of MOFs. Post-synthesis modifications with amine functional groups have been known to increase CO2 sorption capacity and selectivity within nanoporous materials. For ZIFs, previous research showed that sufficient loading with linear polyethyleneimine increased their CO2 sorption capacity. Therefore, the objectives of this research were to a) investigate the CO2 sorption capacity of ZIF-8 synthesized by solvothermal methods that use more eco-friendly solvents (e.g., methanol and water) and b) introduce post-synthetic modifications to ZIF-8 using branched polyethyleneimine (bPEI) to enhance its sorption capacity. A custom quartz crystal microbalance (QCM) system was assembled and used to measure the CO2 sorption capacity of unmodified and bPEI-modified ZIF-8 sorbent. The tests were conducted at 0.3 - 1 bar. The results showed that the unmodified ZIF-8 synthesized in methanol (ZIF-8-MeOH) had comparable crystal structure, thermal stability, surface area, and chemical properties to that of literature (Ta et.al 2018). ZIF-8-MeOH had a surface area of 1300 m2/g and a CO2 sorption capacity of 0.85 mmol CO2/g ZIF-8 @ 1 bar. This surface area and sorption capacity are comparable to those of ZIF-8 made in dimethylformamide (DMF). Therefore, ZIF-8-MeOH proved to be a worthy candidate MOF for replacing the ZIF-8 made in DMF for CO2 capture research. Water-based ZIF-8 was also synthesized in this study; however, its CO2 sorption capacity was not tested because it exhibited a significantly lower surface area (732 m2/g) compared to that of ZIF-8-MeOH. Modification of the ZIF-8-MeOH with bPEI resulted in a decrease in its CO2 sorption capacity. This undesired outcome is likely a result of insufficient bPEI load (mass attached), on ZIF-8-MeOH (~ 10% w/w) combined with the surface area lost (~ 770 m2/g) due to bPEI blocking some of the ZIF-8-MeOH pores. Therefore, the bPEI load attained in this study was not enough to compensate for the loss of surface area of the modified ZIF-8 and thus, the CO2 sorption capacity decreased. Future investigations should enhance the post-synthetic modification by increasing the loading of amine functional groups onto the eco-friendlier ZIF-8-MeOH used in this study.

Polymeric membranes exhibit a trade-off between permeability and selectivity in gas separations which limits their viability as an economically feasible post-combustion carbon capture technology. One approach to improve the separation properties of polymeric membranes is the inclusion of particulate materials into the polymer matrix to create what are known as mixed matrix membranes (MMMs). By combining the polymer and particulate phases, beneficial properties of both can be seen in the resulting composite material. One of the most notable challenges in producing mixed matrix membranes is in the formation of performance-hindering defects at the polymer-filler interface. Non-selective voids or polymer chain rigidification are but two non-desirable effects which can be observed. The material selection and synthesis route are key to minimising these defects. Thin membranes are also highly desirable to achieve greater gas fluxes and improved economical separation processes. Hence smaller nano-sized particles are of particular interest to minimise the disruption to the polymer matrix. This is a challenge due to the tendency of some small particles to form agglomerations. This work involved introducing novel nanoscale filler particles into PEBAX MH1657, a commercially available block-copolymer consisting of poly(ethylene oxide) and nylon 6 chains. Poly(ether-b-amide) materials possess an inherently high selectivity for the CO2/N2 separation due to polar groups in the PEO chain but suffer from low permeabilities. Mixed matrix membranes were fabricated with PEBAX MH1657 primarily using two filler particles, nanoscale ZIF-8 and novel nanoscale MCM-41 hollow spheres. This work primarily investigated the effects of the filler loading on both the morphology and gas transport properties of the composite materials. The internal structure of the membranes was examined using scanning electron microscopy (SEM), and the gas transport properties determined using a bespoke time-lag gas permeation apparatus. ZIF-8 is a zeolitic imidazolate framework which possesses small pore windows that may favour CO2 transport over that of N2. ZIF-8-PEBAX membranes were successfully synthesised up to 7wt.%. It was found that for filler loadings below 5wt.%, the ZIF-8 was well dispersed within the polymer phase. At these loadings modest increases in the CO2 permeability coeffcient of 0-20% compared to neat PEBAX were observed. Above this 5wt.% loading large increases in both CO2, N2 and He permeability coeffcients coincided with the presence of large micron size clusters formed of hundreds of filler ZIF-8 particles. The increases in permeability were attributed to voids observed within the clusters. MCM-41 is a metal organic framework that has seen notable interest in the field of carbon capture, due to its tunable pore size and ease of functionalisation. Two types of novel MCM-41 hollow sphere (MCM-41-HS) of varying pore size were incorporated into PEBAX and successfully used to fabricate MMMs up to 10wt.%. SEM showed the MCM-41 generally interacted well with the polymer with no signs of voids and was generally well dispersed. However, some samples of intermediate loading in both cases showed highly asymmetric distribution of nanoparticles and high particle density regions near one external face of the membrane which also showed the highest CO2 permeability coeffcients. It is suspected that these high permeabilities are due to the close proximity of nanoparticles permitting these regions to act in a similar way to percolating networks. It was determined that there was no observable effect of the varying pore size which was expected given the transport in the pores should be governed by Knudsen diffusion.

No description available.

Η παρούσα εργασία αφορά στη μελέτη της ανταγωνιστικής αλληλεπίδρασης των Α1/D1 υποδοχέων στο επίπεδο έκφρασης του πρώιμου γονιδίου zif/268 (δείκτης νευρωνικής δραστηριότητας) και της in vivo μεταγωγής σήματος των Α1 και Α2Α υποδοχέων αδενοσίνης κάτω από τη ντοπαμινεργική απονεύρωση στο μυ weaver. Ο μυς weaver αποτελεί ένα γενετικό μοντέλο ντοπαμινεργικής απονεύρωσης, η οποία συμβαίνει σταδιακά, έτσι ώστε το μοντέλο αυτό να προσομοιάζει τη Νόσο Πάρκινσον (ΝΠ) στον άνθρωπο. Στο πρώτο στάδιο της μελέτης προέκυψε το ενδιαφέρον αποτέλεσμα ότι με την ταυτόχρονη ενεργοποίηση των Α1 και D1 υποδοχέων παρατηρήθηκε η αναμενόμενη ανταγωνιστική αλληλεπίδραση (ενδεχομένως μέσω σχηματισμού του ετεροδιμερούς), ενώ με την ενεργοποίηση μόνο των Α1 υποδοχέων στους weaver μύες παρατηρήθηκε αυξημένη ενεργοποίηση των νευρώνων του ραβδωτού σώματος και συγκεκριμένων περιοχών του εγκεφαλικού φλοιού. Η ενεργοποίηση αυτή ήταν μη αναμενόμενη, δεδομένου ότι οι Α1 υποδοχείς (A1Rs) είναι συζευγμένοι με Gi πρωτεΐνες και καταστέλλουν τη μεταγωγή σήματος που οδηγεί στην επαγωγή του zif/268 μέσω του D1R/Gs/cAMP/PKA/pDARPP-32/pCREB μονοπατιού. Η ακόλουθη διερεύνηση του μηχανισμού έδειξε ότι η Α1R-επαγόμενη ενεργοποίηση του zif/268 καταστέλλεται από τον ειδικό ανταγωνιστή των Α2Α υποδοχέων αδενοσίνης (A2ARs) ZM241385 και από τον ειδικό αγωνιστή των D2 υποδοχέων ντοπαμίνης Quinpirole, υποδεικνύοντας την ενεργοποίηση των Α2ΑRs και άρα ενεργοποίηση της έμμεσης οδού. Το αποτέλεσμα αυτό επιβεβαιώθηκε, δεδομένου ότι η διέγερση των Α1Rs προκάλεσε αύξηση της έκφρασης του mRNA της εγκεφαλίνης, αλλά όχι της δυνορφίνης, που αποτελούν δείκτες ενεργοποίησης της έμμεσης και της άμεσης οδού, αντίστοιχα. Το γεγονός ότι ο αγωνιστής των Α1Rs δεν προκαλεί στα φυσιολογικά ζώα ενεργοποίηση του zif/268 mRNA υποδεικνύει την υπερευαίσθητη απόκριση των Α2ARs. Η μελέτη της υπερευαίσθητης αυτής απόκρισης στο μυ weaver έγινε με τη διερεύνηση της μεταγωγής σήματος μετά από in vivo ενεργοποίηση των Α2ΑRs: α) του καθιερωμένου μονοπατιού Α2ΑRs/Gs/AC/cAMP/PKA/pDARPP-32/pCREB, το οποίο οδηγεί στη επαγωγή του zif/268 και β) του μονοπατιού των ΜΑΡΚ. Τα αποτελέσματα έδειξαν αυξημένα βασικά επίπεδα φωσφορυλίωσης της DARPP-32 στη θέση Thr-34. Τα αυξημένα επίπεδα της φωσφορυλιωμένης DARPP-32 πολλαπλασιάζουν τη δράση της ΡΚΑ και άρα διευκολύνουν τη μεταγωγή σήματος μέσω Α2ΑRs/Gs/AC/cAMP/PKA/pDARPP-32/pCREB μονοπατιού. Επομένως, η υπερευαίσθητη απόκριση των Α2ΑRs κάτω από την έλλειψη ντοπαμίνης στο μυ weaver φαίνεται να οφείλεται στα αυξημένα ενδογενή επίπεδα της φωσφορυλιωμένης DARPP-32. Ενδιαφέρον παρουσιάζει το γεγονός ότι τα βασικά επίπεδα φωσφορυλίωσης των πρωτεϊνών ERK1/2(MAPK44/42) είναι αυξημένα στον μυ weaver, αλλά μειώνονται σημαντικά μετά από την ενεργοποίηση των Α2ΑRs. Δεν γνωρίζουμε το μηχανισμό μέσω του οποίου αυξάνονται τα ενδογενή επίπεδα των ERK1/2 και πρέπει να διερευνηθεί περαιτέρω. Το συμπέρασμα όμως που εξάγεται είναι ότι κάτω από τη ντοπαμινεργική απονεύρωση η μεταβίβαση σήματος μέσω των Α2ΑRs δεν ενεργοποιεί την οδό των MAP κινασών. Στην παρούσα in vivo μελέτη αναδεικνύεται ο ρόλος των Α1 και Α2Α υποδοχέων στην λειτουργία των βασικών γαγγλίων κάτω από τη ντοπαμινεργική απονεύρωση. Τα αποτελέσματα αυτά έχουν ιδιαίτερη σημασία δεδομένου ότι εμφανίζονται σε ένα γενετικό μοντέλο παρκινσονισμού, στο οποίο η εκφύλιση των ντοπαμινεργικών νευρώνων είναι σταδιακή και προσομοιάζει τη ΝΠ, και όχι οξεία, όπως σε άλλα τοξικά μοντέλα. Επιπλέον, τα αποτελέσματα αυτά παρουσιάζουν ενδεχομένως κλινικό ενδιαφέρον, δεδομένου ότι η ενεργοποίηση της έμμεσης οδού μέσω Α1Rs από την ενδογενή αδενοσίνη θα επιδείνωνε περαιτέρω τις κινητικές δυσλειτουργίες της ΝΠ. Η πληροφορία αυτή, καθώς και η γνώση για την ενισχυμένη μεταγωγή σήματος μέσω των Α2Α υποδοχέων ενισχύουν την πρόταση για χρήση των Α2Α ανταγωνιστών ως αντιπαρκινσονικά φάρμακα. Δεδομένου ότι σήμερα το ενδιαφέρον είναι στραμμένο στη δημιουργία διμερών προσδεμάτων (bivalent ligands) που μπορούν να δρουν ταυτόχρονα σε δύο υποδοχείς, η συγκεκριμένη πληροφορία θα μπορούσε να χρησιμοποιηθεί για μελλοντική δημιουργία φαρμακευτικού σχήματος που να δρα ταυτόχρονα ως αγωνιστής των D2 υποδοχέων ντοπαμίνης και ως ανταγωνιστής των Α2Α υποδοχέων αδενοσίνης. / The present work studied the antagonistic interaction of A1/D1 receptors at the level of mRNA expression of the immediate early gene zif/268 (used as a marker of neuronal function). In parallel we studied the in vivo signal transduction of A1 and A2A adenosine receptors under dopamine deficiency in weaver mutant. The weaver mutant represents the only genetic animal model of gradual nigrostriatal neuron degeneration, which can be characterized as a pathophysiological phenocopy of Parkinson’s Disease. In the first part of the study, the co-activation of A1 and D1 receptors revealed the well-known antagonistic interaction of these receptors (possibly through the formation of A1/D1 heterodimer) in weaver mutant. An interesting result was that the activation of A1 receptors alone did induce zif/268 mRNA expression in stiatal and specific cortical neurons in weaver mutant. This induction was not expected, since A1 receptors are Gi-coupled and suppress the signal transduction pathway that leads to zif/268 induction through AC/PKA/p-DARPP-32/pCREB cascade. Further study, revealed that the A1 receptor-induced zif/268 mRNA expression is counteracted by the A2A receptor selective antagonist ZM241385 and by the D2 receptor selective agonist Quinpirole, suggesting the activation of A2A receptors and thus the activation of the “indirect pathway”. Moreover, A1 receptors activation induced the expression of enkephalin mRNA, but not of dynorphin, which are considered as marker of neuronal activation of the “indirect” and the “direct” pathway, respectively. The fact that the A1 receptor agonist did not induced zif/268 mRNA expression in +/+ animals indicates that under dopamine deficiency the A2A receptors react with a supersensitive response. This response was analyzed in weaver mouse after in vivo A2A receptor activation: a) by examining the classical signal transduction pathway of A2A receptors/AC/PKA/p-DARPP-32/pCREB, which leads to zif/268 expression and b) by studying the MAPK cascade. Results showed increased basal phosphorylation levels of DARPP-32 (dopamine- and cAMP-regulated phosphoprotein, MW 32kDa) of Thr-34 in weaver compared to control mice. Increased phosphoThr34-DARPP-32 would amplify the effects of the PKA and thus facilitating the signal transduction through A2A receptors/AC/PKA/p-DARPP-32/pCREB. Therefore, the A2A receptors supersensitive response under dopamine deficiency in weaver mutant seems to be due to elevated endogenous phosphorylation levels of DARPP-32. Interestingly, while the basal phosphorylation levels of ERK1/2 (MAPK44/42) are elevated in weaver mutant, they are significantly reduced after A2A receptor activation. Although we do not know the mechanism through which the endogenous ERK1/2 levels are elevated, the conclusion is that, under dopamine deficiency, A2A receptors do not activate MAPK cascade. The present in vivo study demonstrates the role of A1 and A2A adenosine receptors in the function of basal ganglia under dopamine deficiency. Our results are significant since the expreriments were performed in a genetic parkinsonian model, in which the dopaminergic neurons are gradually degenerated and thus simulate the human PD, and not in an acute toxic model. Moreover, these results could be of possible clinical relevance, since the activation of A1 receptors by endogenous adenosine would exaggerate the motor dysfunctions of PD. Furthermore, the enhanced signal transduction pathway through A2A receptors supports the suggestion that the A2A receptor antagonists as antiparkinsonian agents. Given the well-known A2A/D2 antagonistic interaction, new therapeutical prospectives would involve the development of pharmacological bivalent ligands, which can interact with the A2A/D2 receptors and act simultaneously as A2A receptor antagonists and as D2 receptor agonists.

Οι αυτοαναπαραγόμενοι επισωματικοί φορείς γονιδιακής μεταφοράς αποτελούν πολλά υποσχόμενους φορείς γονιδιακής θεραπείας. Στην παρούσα εργασία δημιουργήθηκε ο φορέας Zif-VP64-EP2 στα πλαίσια των μελετών γονιδιακής θεραπείας για τις αιμοσφαιρινοπάθειες. Πρόκειται για ένα κυκλικό πλασμίδιο, που φέρει το γονίδιο ενός τεχνητού μεταγραφικού παράγοντα της γ-σφαιρίνης του Zif-VP64 υπό την επενέργεια του ισχυρού υποκινητή pSFFV καθώς και τo γονίδιο της eGFP με το S/MAR στοιχείο από την περιοχή 5’ του γονιδίου της ανθρώπινης ιντερφερόνης β υπό την επενέργεια του υποκινητή pCMV. Διαπιστώθηκε ότι το Zif-VP64-EP2 μεσολαβεί γονιδιακή μεταφορά σε διαμολυσμένα κύτταρα της ανθρώπινης κυτταρικής σειράς Κ562. Η μακράς διάρκειας διαμολυσμένη καλλιέργεια (3 μήνες) καταδεικνύει ότι το όχημα είναι λειτουργικό και διατηρείται ως επισωματικό σε Κ562 κύτταρα διαμολυσμένα κύτταρα με το Zif-VP64- ΕΡ2. / Self-replicating episomal vectors for gene transfer are a new and very promising experimental approach to gene therapy. In this study, it was created the vector Zif-VP64-EP2, within the context of developing self-replicating episomal vectors for the gene therapy of hemoglobinopathies. Zif-VP64-EP2 is a circular plasmid which includes the gene of an artificial transcription factor for gamma globin: Zif-VP64 under the control of pSFFV promoter and the gene of eGFP with the S/MAR element from the region 5’ of the human interferon β gene under the control of pCMV promoter. It was established that Zif-VP64-EP2 was retained within the transfected Κ562 hematopoietic progenitor cell. Its episomal situation for a long time (3 months) and its normal expression in K562 human cells constitutes a proof of the utility of Zif-VP64- ΕΡ2 system in gene therapy applications.

This project relates to the non-classical growth of inorganic crystals with interesting morphologies that are highly desirable in industry. All crystals were synthesized via hydrothermal or solvothermal methods and their growth was studied by stopping each reaction at a range of different times, extracting the particles and analysing them using a variety of characterisation techniques. The main techniques used were scanning electron microscopy and transmission electron microscopy but other techniques, such as powder X-ray diffraction and thermal gravimetric analysis, were also employed. Decorated ZnO microstadiums were studied where ZnO nanocones coat the inner and outer columnar walls of ZnO microstadiums. It was revealed that the polymer in the synthetic solution enhanced the aggregation of nanocrystallites of precursor ions on the microstadium surfaces, which then underwent recrystallization, forming ZnO nanocones. The presence of organic agents was also found to be crucial in the non-classical growth mechanisms of CaCO₃ and RHO-ZIF crystals as the presence of charged groups on the organic molecules led to the aggregation of precursor molecules/ions, preventing classical growth. The disordered aggregates underwent surface recrystallization, forming ‘core-shell' structures where a thin layer of single crystal encased a disordered core. Over time the crystallisation extended from the surface inwards, towards the core, until true single crystals were formed. Organic molecules were also shown to play a role in the non-classical growth of 8-branched Cu₂O structures. In this case, however, studies of the electronic configuration of the main terminating facets of Cu₂O crystals revealed another key factor in their non-classical growth. Terminating hydroxyl groups on the Cu₂O surfaces could have different charges depending on the number of Cu⁺ ions they were coordinated to. The terminating {111} faces were the only ones to be coated with negatively charged hydroxyl groups, which explained the rapid growth on these surfaces as they were able to attract the positively charged metal/polymer precursor clusters. This new phenomenon was also found to be the main driving force in the rapid growth of branches in snowflake-like Fe₂O₃ crystals despite no organic agent being used. In this case, the {11-20} faces of the seed crystals had positively charged hydroxyl groups that were able to rapidly attract the negatively charged [Fe(CN) ₆]³⁻ ions in the aqueous solution.

Tesis por compendio / [ES] El desarrollo de membranas poliméricas capaces de actuar como electrolito en pilas de combustible tipo PEMFC a temperaturas intermedias constituye uno de los principales retos para conseguir la generación eficiente de energía por medio de estos dispositivos. Actualmente, las membranas basadas en polímeros perfluorosulfonados como el Nafion® son las más extendidas en pilas de combustible, ya que presentan una buena conductividad protónica además de ser estables mecánica y químicamente. Sin embargo, este tipo de membranas no son capaces de ofrecer buenos rendimientos por encima de 80 ¿C. En este sentido, el objetivo fundamental de esta tesis ha sido la síntesis y caracterización de membranas poliméricas que permitan su potencial utilización en el rango de temperaturas intermedias, por encima de 100 ¿C, donde la cinética de los electrodos y el transporte de protones a través de la membrana mejoran considerablemente, aumentando con ello el rendimiento de la celda. La investigación llevada a cabo se ha centrado en dos tipos de polímeros: poli(eter-eter-cetona) sulfonada (SPEEK) y polibencimidazol (PBI). Las membranas basadas en SPEEK ofrecen una elevada conductividad protónica y una buena estabilidad tanto mecánica como química. Si bien, estas propiedades dependen drásticamente de su grado de sulfonación. Así, altos grados de sulfonación resultan en muy buenas conductividades protónicas, aunque por el contrario, originan un excesivo hinchamiento de las membranas provocando un empeoramiento de sus propiedades mecánicas. Además, cuando la temperatura supera los 80 ¿C su conductividad disminuye debido a la deshidratación de la membrana. La estrategia seguida en este caso para mantener las propiedades mecánicas y la conductividad de las membranas basadas en SPEEK a temperaturas intermedias ha consistido en utilizar un polímero con un índice de intercambio catiónico no excesivamente alto (1.75 meq g-1), el cual ha sido dopado con dos tipos de compuestos organometálicos diferentes de tipo ZIF (Zeolitic Imidazolate Framework ) y con una mezcla de ambos. Este tipo de compuestos constituyen una subclase de los conocidos como Metal Organic Framework (MOF), los cuales adoptan una estructura tipo zeolita donde la parte orgánica está constituida por un anillo de imidazol y el nodo inorgánico es un metal. En este caso Zinc para el Z8 y Cobalto para el Z67. Las membranas compuestas SPEEK-ZIF mejoraron claramente las prestaciones de las de SPEEK puro a temperaturas intermedias. En base a los resultados anteriores, se seleccionaron las membranas dopadas con ZIF-67 para su evaluación en monocelda donde ofrecieron valores superiores a los de las membranas de SPEEK puro sin la adición de cargas y a los obtenidos con membranas de Nafion®117 a temperaturas superiores a 100 °C. En el caso de las membranas en base PBI, estas han sido capaces de ofrecer valores elevados de conductividad a altas temperaturas cuando eran dopadas con ácido fosfórico. Sin embargo, la pérdida del ácido por parte de la membrana (leaching) con el tiempo de operación y la degradación que este ácido provoca en los componentes de la celda, hacen que sea necesaria la utilización de otros agentes dopantes no volátiles y menos agresivos capaces de aportar al polímero la conductividad de la que carece. Los líquidos iónicos son sales fundidas a temperatura ambiente que poseen presiones de vapor despreciables y ofrecen buenas conductividades a temperaturas elevadas. En esta tesis, se prepararon por el método de casting, membranas de PBI conteniendo el líquido iónico 1-butil-3-metil imidazolio bis(trifluorometil sulfonil) imida (BMIM-NTf2) en diferentes porcentajes. Estas membranas alcanzaron a partir de un 10 % wt. de líquido iónico un valor de conductividad del orden de 10-2 S cm-1 a 160 ¿C. Señalando su potencial como electrolito polimérico basado en PBI libre de ácido fosfórico. / [CA] El desenvolupament de membranes polimèriques vàlides per a actuar com a electròlit en piles de combustible tipus PEMFC a temperatures intermèdies. Constitueix un dels reptes principals per aconseguir la generació eficient d'energia amb aquests dispositius. Actualment, les membranes basades en polímers perfluorosulfonats com el Nafion® són les més utilitzades en piles de combustible, ja que presenten una bona conductivitat protònica a més de tindre una bona estabilitat química i mecànica. Tot i això, aquest tipus de membranes no oferixen bons rendiments a temperaturas superiors a 80 ¿C. En aquest sentit, l'objectiu fonamental d'aquesta tesi ha segut la síntesi i caracterització de membranes polimèriques amb les característiques adequades per poder treballar a temperatures intermèdies, per damunt de 100 ¿C. En aquestes condicions la cinètica dels elèctrodes i el transport de protons a través de la membrana milloren considerablement augmentant amb això el rendiment de la cel·la. La investigació duta a terme s'ha centrat en dos tipus de polímers: poli(eter-eter-cetona) sulfonada (SPEEK) i polibencimidazol (PBI). Les membranes basades en SPEEK ofereixen una elevada conductivitat protònica i una bona estabilitat tant mecànica com a química. No obstant això, aquestes caracteristiques depenen dràsticament del seu grau de sulfonació. Així, alts graus de sulfonació resulten en molt bones conductivitats protòniques. Encara que per contra, originen un excessiu unflament de les membranes en aigua calenta provocant un empitjorament de les seves propietats mecàniques. A més, quan la temperatura supera els 80 ¿C la seva conductivitat baixa a causa de la deshidratació de la membrana. L'estratègia seguida en aquest cas per mantenir les propietats mecàniques i la conductivitat de les membranes basades en SPEEK a temperatures intermèdies. Ha segut partir d'un polímer amb un índex d'intercanvi catiònic no gaire alt (1.75 meq g-1). El qual ha segut dopat amb dos tipus de compostos órganometàl.lics diferents de tipus ZIF (Zeolitic Imidazolate Framework) (ZIF) i amb una barreja de tots dos. Aquest tipus de compostos constitueixen una subclasse dels coneguts com a Metal Organic Framework (MOF). Els quals adopten una estructura tipus zeolita on la part orgànica està constituïda per un anell d'imidazol i el node inorgànic és el metall. En aquest cas Zinc per al Z8 i Cobalt per al Z67. Les membranes compostes SPEEK-ZIF van millorar clarament les prestacions de les de SPEEK pur a temperatures intermèdies. En base als resultats anteriors es van seleccionar les membranes dopades amb ZIF-67 per a la seva avaluació en monocel·la on van oferir valors superiors als de les membranes de SPEEK pur sense l'addició de càrregues i als obtinguts amb membranes de Nafion®117 en les mateixes condicions a temperatures superiors a 100 °C. En el cas de les membranes en base PBI, aquestes han oferit valors elevats de conductivitat a altes temperatures, quan han segut dopades amb àcid fosfòric. Tot i això, la pèrdua de l'àcid per part de la membrana (leaching) amb el temps d'operació i la degradació que aquest àcid provoca en els components de la cel·la, fan que siga necessària la utilització d'altres agents dopants no volàtils i menys agressius capaços d'aportar al polímer conductivitat iònica. Els líquids iònics són sals foses a temperatura ambient que tenen pressions de vapor molt febles i ofereixen bones conductivitats a temperatures elevades. En aquesta tesi es van preparar pel mètode de càsting, membranes de PBI contenint el líquid iònic 1-butil-3-metil imidazoli bis(trifluorometil sulfonil) imida (BMIM-NTf2) en diferents percentatges. Aquestes membranes van assolir a partir d'un 10% wt. de líquid iònic un valor de conductivitat de l'ordre de 10-2 S cm-1 a 160 ¿C. Assenyalant el seu potencial com a electròlit polimèric basat en PBI lliure d'àcid fosfòric. / [EN] The development of polymeric membranes capable of acting as an electrolyte in a proton exchange membrane fuel cells (PEMFC) at intermediate temperatures. It constitutes one of the main challenges to achieve efficient energy generation through these kinds of devices. Currently, membranes based on perfluorosulfonated polymers such as Nafion® are the most widespread in fuel cells, since they have good proton conductivity as well as being mechanically and chemically stable. However, these types of membranes are not capable of offering good performance above 80 ¿C. In this sense, the main objective of this thesis has been the synthesis and characterization of polymeric membranes with potential use in the range of intermediate temperatures, above 100 ¿C, where the kinetics of the electrodes and the transport of protons through of the membrane and the performance of the cell are greatly improved. The research carried out has focused on two types of polymers: sulfonated poly(ether-ether-ketone) (SPEEK) and polybenzimidazole (PBI). SPEEK-based membranes offer high proton conductivity and good mechanical and chemical stability. However, their properties depend dramatically on its degree of sulfonation. Thus, high degrees of sulfonation result in excellent proton conductivities. On the other hand, the large amount of sulphonic groups in the membrane cause an excessive swelling in hot water, leading to a worsening of their mechanical properties, even reaching its dissolution. Furthermore, as also happens with perfluorosulfonated membranes, when the temperature is increased above 80 ¿C their proton conductivity decreases due to membrane dehydration. Focused on maintain the mechanical properties and conductivity of SPEEK-based membranes at intermediate temperatures. Membranes have been prepared from a polymer with a not excessively high cation exchange rate (1.75 meq g-1). Which has been doped with two different ZIF-type (Zeolitic Imidazolate Framework) organometallic compounds and with a mixture of both. This type of compounds constitutes a subclass of those known as Metal Organic Framework (MOF). Which adopt a zeolite-type structure where the organic part is made up of an imidazole ring and the inorganic node is the metal. In this case Zinc for Z8 and Cobalt for Z67. SPEEK-ZIF. Composite membranes clearly improved the performance of pure SPEEK membranes at intermediate tempe-ratures. Based on the previous results, the membranes doped with ZIF-67 were selected for their evaluation in a single fuel cell, where they offered higher values than those of the pure SPEEK membranes without the addition of fillers and those obtained with membranes of Nafion®117 under the same conditions at temperatures above 100 °C. PBI based membranes, have been capable of offering high conductivity values at high temperatures, when they have been doped with phosphoric acid. However, the loss of acid by the membrane (leaching) with the operation time and the degradation that this acid causes in the cell components. In this sense, it is necessary to explore the use of other non-volatile and less aggressive doping agents capable of providing ionic conductivity to the polymer. Ionic liquids are molten salts at room temperature that have negligible vapor pressures and offer good conductivities at elevated temperatures. In this thesis, PBI membranes containing the ionic liquid 1-butyl-3-methyl imidazolium bis(trifluoromethyl sulfonyl)imide (BMIM-NTf2) at different percentages were prepared by the casting method. These membranes containing 10 wt.% of ionic liquid reached a conductivity value in the range of 10-2 S cm-1 at 160 ¿C. Noting its potential as a phosphoric acid-free PBI-based polymeric electrolyte. / This work was sponsored by the Ministerio de Economia y Competitividad (MINECO) under the project ENE/2015-69203-R. The authors acknowledge the Electron Microscopy Service from Universitat Politècnica de València for the use of instruments and staff assistance. / Barjola Ruiz, A. (2023). Membranas poliméricas de intercambio iónico con aplicación en pilas de combustible de temperatura intermedia [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/193081 / Compendio