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Este trabalho foi dividido em duas partes, sendo que na primeira (PARTE A) estão apresentadas as sínteses dos polímeros PPV, Cl-PPV, Br-PPV e dos co-polímeros (Cl-PPV)m / (PPV)n e (Br-PPV)m / (PPV)n nas seguintes relações m:n de 30:70; 50:50 e 70:30. Estes polímeros foram caracterizados por espectroscopia de infravermelho, UV-Visível e emissão de fluorescência. As modificações causadas nos polímeros, devido a dopagem com vapor de iodo e solução de cloreto férrico 0,12M em nitrometano também foram estudadas por estas mesmas técnicas. O acompanhamento da dopagem do PPV com vapor de iodo permitiu fazer a atribuição das bandas polarônicas e bipolarônicas por espectroscopia óptica. Também foram feitas medidas de voltametria cíclica que permitiram avaliar parâmetros eletrônicos importantes destes polímeros, tais como a Afinidade Eletrônica (HOMO), Potencial de Ionização (LUMO) e o GAP que é a diferença entre esses dois níveis de energia. Os co-polímeros apresentaram valores de energia do GAP menores que o PPV e níveis de energia de HOMO e de LUMO que podem ser apropriados para a utilização destes materiais em dispositivos eletroluminescentes (LED). Na PARTE B está apresentada a síntese de um composto inédito o 4- (2-fenoxi-p-xileno)-N-metil-1,8-naftalimida aqui chamado de NPOX. A caracterização do NPOX foi feita por espectroscopia de ressonância magnética v nuclear de próton (RMN 1H), espectrometria de massas (CG/MS), UV-Vis e Emissão de Fluorescência. O NPOX é solúvel em clorofórmio, que quando evaporado promove a formação de um filme transparente. Este filme tem emissão de fluorescência em 456 nm sendo excitado em 363 nm O filme também apresentou um comportamento semelhante a dos diodos demonstrado pela medida elétrica de corrente versus potencial (curva I x V). Estas propriedades abrem a possibilidade da utilização do NPOX como camada ativa, com emissão no azul, em OLED (Dispositivos Eletroluminescentes Orgânicos). / This work was separated in two parts, in the first, called PART A, the synthesis of the polymers PPV, Cl-PPV, Br-PPV and of the co-polymers (Cl-PPV)m / (PPV)n and (Br-PPV)m / (PPV)n in the following relationships m:n of 30:70; 50:50 and 70:30 are presented. These polymers were characterized by infrared spectroscopy, UVvisible and fluorescence emission. The modifications caused in the polymers due to the doping with iodine vapor and 0,12M ferric chloride in nitrometano solution were studied also by these same techniques. The doping of PPV with iodine vapor have been monitored by optical spectroscopy allowing us to do the attribution of the polaronic and bipolaronic bands. Measurements of cyclic voltametry revealed important electric properties of these polymers, such as the Electronic Affinity (HOMO), Ionization Potential (LUMO) and \" GAP \" that is the difference between those two energy levels. The co-polymers presented smaller values of GAP than PPV and HOMO and of LUMO energy levels that can be appropriate to the use these materials in Light-Emitting Devices (LED). In PARTE B, the synthesis of an unpublished compound is presented, the 4-(2-fenoxi-p-xileno)-N-methyl-1,8-naftalimida, here called as NPOX. The characterization of NPOX was made by of nuclear magnetic resonance of proton vii spectroscopy (1H NMR), Gas Cromatography/ Mass Spectrometry (GC/MS), UVVisible and Fluorescence Emission spectroscopy. NPOX is soluble in chloroform that when evaporated it promotes in a transparent film formation. This film has fluorescence emission in 456 nm when excited in 363 nm. The film also showed a similar behavior as diodes that was demonstrated by the electric measurement of current versus potential (I x V curve). These properties open the possibility of the use of NPOX as activate layer, with emission in the blue region, in OLED (Organic Light- Emitting Devices).

Este trabalho foi dividido em duas partes, sendo que na primeira (PARTE A) estão apresentadas as sínteses dos polímeros PPV, Cl-PPV, Br-PPV e dos co-polímeros (Cl-PPV)m / (PPV)n e (Br-PPV)m / (PPV)n nas seguintes relações m:n de 30:70; 50:50 e 70:30. Estes polímeros foram caracterizados por espectroscopia de infravermelho, UV-Visível e emissão de fluorescência. As modificações causadas nos polímeros, devido a dopagem com vapor de iodo e solução de cloreto férrico 0,12M em nitrometano também foram estudadas por estas mesmas técnicas. O acompanhamento da dopagem do PPV com vapor de iodo permitiu fazer a atribuição das bandas polarônicas e bipolarônicas por espectroscopia óptica. Também foram feitas medidas de voltametria cíclica que permitiram avaliar parâmetros eletrônicos importantes destes polímeros, tais como a Afinidade Eletrônica (HOMO), Potencial de Ionização (LUMO) e o GAP que é a diferença entre esses dois níveis de energia. Os co-polímeros apresentaram valores de energia do GAP menores que o PPV e níveis de energia de HOMO e de LUMO que podem ser apropriados para a utilização destes materiais em dispositivos eletroluminescentes (LED). Na PARTE B está apresentada a síntese de um composto inédito o 4- (2-fenoxi-p-xileno)-N-metil-1,8-naftalimida aqui chamado de NPOX. A caracterização do NPOX foi feita por espectroscopia de ressonância magnética v nuclear de próton (RMN 1H), espectrometria de massas (CG/MS), UV-Vis e Emissão de Fluorescência. O NPOX é solúvel em clorofórmio, que quando evaporado promove a formação de um filme transparente. Este filme tem emissão de fluorescência em 456 nm sendo excitado em 363 nm O filme também apresentou um comportamento semelhante a dos diodos demonstrado pela medida elétrica de corrente versus potencial (curva I x V). Estas propriedades abrem a possibilidade da utilização do NPOX como camada ativa, com emissão no azul, em OLED (Dispositivos Eletroluminescentes Orgânicos). / This work was separated in two parts, in the first, called PART A, the synthesis of the polymers PPV, Cl-PPV, Br-PPV and of the co-polymers (Cl-PPV)m / (PPV)n and (Br-PPV)m / (PPV)n in the following relationships m:n of 30:70; 50:50 and 70:30 are presented. These polymers were characterized by infrared spectroscopy, UVvisible and fluorescence emission. The modifications caused in the polymers due to the doping with iodine vapor and 0,12M ferric chloride in nitrometano solution were studied also by these same techniques. The doping of PPV with iodine vapor have been monitored by optical spectroscopy allowing us to do the attribution of the polaronic and bipolaronic bands. Measurements of cyclic voltametry revealed important electric properties of these polymers, such as the Electronic Affinity (HOMO), Ionization Potential (LUMO) and \" GAP \" that is the difference between those two energy levels. The co-polymers presented smaller values of GAP than PPV and HOMO and of LUMO energy levels that can be appropriate to the use these materials in Light-Emitting Devices (LED). In PARTE B, the synthesis of an unpublished compound is presented, the 4-(2-fenoxi-p-xileno)-N-methyl-1,8-naftalimida, here called as NPOX. The characterization of NPOX was made by of nuclear magnetic resonance of proton vii spectroscopy (1H NMR), Gas Cromatography/ Mass Spectrometry (GC/MS), UVVisible and Fluorescence Emission spectroscopy. NPOX is soluble in chloroform that when evaporated it promotes in a transparent film formation. This film has fluorescence emission in 456 nm when excited in 363 nm. The film also showed a similar behavior as diodes that was demonstrated by the electric measurement of current versus potential (I x V curve). These properties open the possibility of the use of NPOX as activate layer, with emission in the blue region, in OLED (Organic Light- Emitting Devices).

Block copolymers can self-assemble into a variety of periodic nanostructures and therefore, are promising candidates for a diverse range of applications. While self-assembly of block copolymers has been widely studied and exploited, graft copolymers have remained far less explored in this context. One of the primary reasons for this is that the most commonly used methods to prepare graft copolymers leads to polymers that do not have precisely defined structures; specifically, controlling the precise location of the grafted segments is a synthetically difficult challenge. In typical chain polymerization processes, statistically random incorporation of monomers takes place and consequently, the periodicity of the grafted segment along the backbone is very difficult to control precisely; therefore, such methods cannot be utilized to prepare periodically grafted copolymers. Some recent efforts towards the preparation of sequence regulated copolymers using controlled radical polymerization in conjunction with periodic dosing of a commoner could provide an alternative to better regulate the periodicity, although this will also not be perfectly periodic. The only approach to control the periodicity perfectly is to utilize condensation polymerization approaches, wherein one of the monomers serve as a spacer whereas the other provides the opportunity to install the graft segment, as depicted in Scheme 1. One of the earliest examples of the utilization of a condensation approach to locate desired units at periodic intervals was reported by Wagener and co-workers using Acrylic Diene Metathesis (ADMET) process.1 ]n periodicity ]n graft segment Scheme 1. Synthetic scheme for the preparation of periodically grafted copolymers using condensation polymerization. From our lab, Roy et al. developed periodically grafted amphiphilic copolymers (PGAC), based on a readily available starting material, diethyl malonate;2 melt trans-esterification between diethyl malonate, containing a pendant hexaethylene glycol monomethyl ether (HEG) segment and 1,22-docosane diol resulted in PGAC wherein the hydrophilic oligo ethylene glycol units were placed on every 27th atom along the backbone (Scheme 2). Such PGAC underwent self-segregation and adopted a folded zigzag conformation, which was driven by the intrinsic immiscibility of the alkylene and HEG segments and was reinforced by the strong tendency for long chain alkylene segments to crystallize in a paraffinic lattice. However, one of the drawbacks of the above approach was that the hydrophilic pendant unit was installed at the monomer stage and consequently, the synthetic approach does not allow easy variation of the hydrophilic grafted segment; this limits the flexibility and any structural variation of the pendant segment would be synthetically tedious. 150 oC DBTDL 5 20 DBTDL = Dibutyltin dilaurate Scheme 2. Synthesis of PGAC, based on diethyl malonate, and immiscibility-driven folding of such PGACs. Mandal et al. developed a more general strategy for the synthesis of such periodically grafted systems; they prepared periodically clickable polyesters carrying propargyl groups at regular intervals, by the solution polycondensation of 2-propargyl-1,3-propanediol or 2,2-dipropargyl-1,3-propanediol and the acid chloride of 1,20-eicosanedioic acid. Such periodically clickable polyesters were shown to react quantitatively with a fluoroalkyl azide3 and PEG 350 azide4, thus allowing them to place different kinds of functionalities precisely along the backbone, as shown in Scheme 3. The immiscibility of the alkylene and fluoroalkyl/PEG segments caused the polymer chains to fold in a zigzag fashion, thereby facilitating the segregation of these segments, as observed earlier in the study by Roy et al.2 The objective of this study was to place various desired functionalities along the polymer backbone and examine their effect on the self-assembly behaviour and morphology of such periodically clicked systems. Scheme 3. Synthetic scheme for the generation of periodically clickable polyesters and their subsequent functionalization via Cu-catalysed click chemistry. In Chapter 2, we describe an alternative general strategy for the scalable synthesis of periodically graftable polyesters and their subsequent functionalization to generate a wide variety of periodically grafted systems. The importance of our approach lies in our choice of the monomer, which is based on itaconic acid, an inexpensive and bio-sourced molecule. We demonstrated that dibutyl itaconate can be melt-condensed with aliphatic diols to generate unsaturated polyesters (Scheme 4); importantly, we showed that the double bonds in the itaconate moiety remain unaffected during the melt polymerization. A particularly useful attribute of these polyesters is that the exo-chain double bonds are conjugated to the ester carbonyl and therefore, can serve as excellent Michael acceptors. A variety of organic thiols, such as alkane thiols, MPEG thiol, thioglycerol, derivative cysteine etc., were shown to quantitatively Michael-add to the exo-chain double bonds and generate interesting functionalized polyesters; similarly, organic amines, such as N-methylbenzylamine, diallyl amine and proline also underwent Michael addition across the double bond (Scheme 4). Thus, such poly(alkylene itaconate)s could be utilized to place diverse functionalities at regular intervals along the polymer backbone. Scheme 4. Preparation of periodically graftable polyesters, based on itaconic acid, and their subsequent modification by Michael addition. In Chapter 3, we examined a series of periodically grafted polyesters carrying long crystallizable alkylene (C-20) segments along the backbone and pendant polyethylene glycol monomethyl ether (MPEG) segments grafted at periodic intervals. Such periodically grafted amphiphilic copolymers (PGAC) having MPEG graft segments of varying lengths were prepared by utilizing the activated exo-chain double bonds in poly(icosyl itaconate) (PII) that carries a 20-carbon alkylene segment; MPEG thiols of varying lengths (TREG, 350, 550 and 750) were quantitatively grafted under standard Michael addition conditions to yield the required graft copolymers, as shown in Scheme 5. Scheme 5. Synthesis of a series of periodically grafted amphiphilic copolymers (PGAC) utilizing post-polymerization modification via Michael addition with MPEG thiols of varying lengths. The immiscibility of the backbone alkylene and pendant MPEG segments, and the strong propensity of the alkylene segments to crystallize in a paraffinic lattice, drive these systems to fold in a zigzag fashion and subsequently organize into a lamellar morphology, as shown in Scheme 6. Interestingly, all the graft copolymers exhibited a clear and invariant melting transition at ~44°C that suggested the crystallization of the backbone C-20 segment; the MPEG segments were, however, amorphous except in the case of polymers carrying MPEG 550/MPEG-750 segments, wherein a second melting transition corresponding to the independent crystallization of the PEG segment was also seen. SAXS studies indicated that all of the samples exhibited lamellar morphologies wherein more importantly, the inter-lamellar spacing was seen to increase linearly with the MPEG length (Scheme 6). This study provides a new design for controlling the dimensions of the microphase-separated nanostructures at significantly smaller length scales (sub-10 nm) than is typically possible using block copolymers. Scheme 6. Schematic representation of formation of lamellar morphology in PGACs and control of interlamellar spacing in such systems. In order to understand the influence of having a mixture of MPEG lengths on the self-assembled morphology, in Chapter 4 we prepared a series of PGACs by co-grafting the parent poly(icosyl itaconate) with a mixture of two different MPEG thiols, namely MPEG-350 and MPEG-750; the mole-ratios of these two PEGs were varied to generate co-grafted PGACs, carrying different amounts of the two MPEG segments randomly distributed along the chain (Scheme 7). Parallely, we also examined the behaviour of physical mixtures of two different PGACs, one bearing MPEG-350 and the other MPEG-750 grafts; keeping the total MPEG content constant, we sought to examine the differences in the behaviour of randomly co-grafted polymers and physical mixtures. Scheme 7. Preparation of co-grafted PGACs and physical mixtures of two different PGACs. The co-grafted PGACs also exhibited a lamellar morphology; interestingly, the inter- lamellar spacing increased linearly with the total volume of PEG domain. This suggested that despite the presence of MPEG segments of two different lengths in the co-grafted samples, there occurred a reorganization of the PEG chains within the amorphous domain ensuring that the condition of incompressibility is not violated, thereby giving rise to a weighted average interlamellar spacing, as shown in Scheme 8. In contrast, the SAXS patterns of the physical mixtures revealed the presence of two distinct lamellar domains in the sample; this indicated that the two homo-grafted samples do not mix and form separate lamellar domains. The self- segregation induced folding and subsequent crystallization of the central alkylene segments clearly appeared to dominate the final morphology. Scheme 8. Schematic depiction of the possible scenarios that could arise when MPEG segments of two different lengths, namely MPEG350 and MPEG750, are present in the PGACs; top panel depicts the co-grafted PGACs, whereas the bottom panel shows the case of mixtures of PGACs with two different MPEG lengths. In Chapter 5, we have dealt with the design and synthesis of chain-end functionalizable polyalkylene itaconates. Changing the monomer from dibutyl itaconate to dipropargyl itaconate and using it in controlled excess allowed us to generate chain-end functionalizable polymers containing propargyl groups at the chain ends, in addition to the exo-chain double bonds along the backbone, thereby providing the opportunity for orthogonal functionalization. In order to obtain three different telechelic polymers with target DPs (degree of polymerization) of 5, 10 and 20 respectively, 3 different mole ratios of the two monomers (dipropargyl itaconate and 1,20-eicosanediol) were used (Scheme 9). Scheme 9. Synthetic scheme for the generation of chain-end functionalizable polyalkylene itaconates. Orthogonal functionalization of the resultant polymers was carried out using thiol-Michael addition and Cu(I)-catalysed alkyne-azide cycloaddition (AAC), without interference between the functional handles present along the polymer backbone and the chain-end, respectively. Michael addition with triethylene glycol thiol and subsequent Cu-catalysed click reaction with MPEG 750 azide led to the generation of ABA type triblock copolymers where the middle block is a periodically grafted amphiphilic block and the two linear end blocks are hydrophilic in nature. Furthermore, such propargyl-terminated polyalkylene itaconates were used as macromonomers to prepare multiblock copolymers. The telechelic polymers were first treated with PEG 600 diazide, resulting in the formation of alternating multiblock copolymers; these multiblock copolymers were further reacted with thioglycerol to generate amphiphilic multiblock copolymers where one of the blocks is a periodically functionalized amphiphilc block, as depicted in Scheme 10. In both these amphiphilic block copolymer systems, a key feature is that the periodically functionalized amphiphilic block folds into a zigzag form, as evident from the presence of a nearly invariant melting peak corresponding to the crystallization of the alkylene segment. Scheme 10. Preparation of multiblock copolymers utilizing propargyl-terminated polyalkylene itaconates as a macromonomer. In summary, the thesis has demonstrated the design and synthesis of a series of novel amphiphilic copolymers using a bio-sourced monomer, wherein the driving theme is the immiscibility driven self-segregation that leads to the folding of the chain; these have been thoroughly examined using DSC, SAXS, WAXS, variable temperature FT-IR and AFM measurements. References (1) Berda, E. B.; Lande, R. E.; Wagener, K. B. Macromolecules 2007, 40, 8547. (2) Roy, R. K.; Gowd, E. B.; Ramakrishnan, S. Macromolecules 2012, 45, 3063. (3) Mandal, J.; Krishna Prasad, S.; Rao, D. S. S.; Ramakrishnan, S. Journal of the American Chemical Society 2014, 136, 2538. (4) Mandal, J.; Ramakrishnan, S. Langmuir 2015, 31, 6035.

[ES] El desarrollo de la sociedad ha estado siempre ligado a los avances científicos y tecnológicos. Sin embargo, algunos de estos avances han supuesto la aparición de nuevos problemas, sobre todo de tipo ético, dando lugar a nuevos movimientos asociativos contrarios a ellos. Un ejemplo de ello es el uso de la experimentación animal, fundamentalmente en el campo de la medicina, y más concretamente en el ensayo de fármacos y dispositivos implantables en contacto con medios biológicos. En este sentido, desde el ámbito de los biomateriales y la ingeniería tisular se trabaja para buscar alternativas a la experimentación animal. Una de estas alternativas es el desarrollo de modelos in vitro a partir de soportes poliméricos para el crecimiento celular in vitro. Estas estructuras, además, podrían emplearse no sólo en ensayos de fármacos o investigación in vitro para reducir el uso de animales en experimentación, sino también para regeneración tisular, simulando desde tejidos simples en los que se tienen un único tipo celular, a tejidos más complejos a partir del co-cultivo celular. Así pues, en esta tesis se ha desarrollado un sistema tridimensional con estructura porosa estratificada que permite tanto el co-cultivo celular indirecto, como la realización de ensayos de liberación de fármacos. Para ello, se ha obtenido soportes porosos (scaffolds) por medio de la técnica de solvent-casting particle-leaching empleando como porógeno sal, cuyo tamaño de poro permite albergar células en su interior, sobre los que se han dispuesto, formando una estructura tipo sándwich, membranas electrohiladas. Estas membranas forman una estructura de fibras entrecruzadas, dejando entre ellas espacios de tamaño muy inferior al tamaño celular, de modo que permiten el paso de nutrientes y moléculas a través de ellas, pero actúan de barrera para las células impidiendo su migración a otras zonas del sistema tridimensional. Este tipo de estructuras permiten simular, por ejemplo, la arquitectura tubular renal, con la zona porosa intersticial central y las dos capas epitelial y endotelial externas, que estarían en contacto con la orina y la sangre, respectivamente. Para obtener estas estructuras, se ha optado por emplear polímeros de la familia de los poliésteres, en particular ácido poliláctico y poli(¿-caprolactona), así como su mezcla y copolímeros con ácido poliglicólico. Estas combinaciones permiten ajustar la hidrofilicidad, y por tanto la biodegradabilidad, la cinética de liberación de fármacos y el comportamiento biológico, según interese. Además, el uso de la técnica de electrospinning para el desarrollo de las membranas, permite obtener diferentes diámetros de fibra a partir de la modificación de los principales parámetros del electrohilado, permitiendo también regular las propiedades de estos materiales. Finalmente, para estudiar la liberación de fármacos desde el sistema anterior, las membranas electrohiladas se han cargado con curcumina mediante dos métodos diferentes: a través del método de electrohilado en disolución y con electrospinning coaxial, para obtener así diferentes perfiles de liberación. / [CA] El desenvolupament de la societat ha estat sempre lligat als avanços científics i tecnològics. Malauradament, alguns d'aquests avanços han suposat l'aparició de nous problemes, sobretot de tipus ètic, donant lloc a nous moviments associatius contraris a ells. Un exemple d'això és l'ús de l'experimentació animal, fonamentalment al camp de la medicina, i més concretament en el testatge de fàrmacs i dispositius implantables en contacte amb medis biològics. En aquest sentit, des de l'àmbit dels biomaterials i l'enginyeria tissular es treballa per a buscar alternatives a l'experimentació animal. Una d'aquestes alternatives és el desenvolupament de models in vitro a partir de suports polimèrics per al creixement cel·lular in vitro. Aquestes estructures, a més a més, podrien emprar-se no sols en testatge de fàrmacs o investigació in vitro per a reduir l'ús d'animals en experimentació, sinó també per a regeneració tissular, simulant des de teixits simples en què es té un únic tipus cel·lular, a teixits més complexos a partir del co-cultiu cel·lular. Així doncs, en aquesta tesi s'ha desenvolupat un sistema tridimensional amb estructura porosa estratificada que permet tant el co-cultiu cel·lular indirecte, com la realització d'assajos d'alliberació de fàrmacs. Per a això, s'ha obtingut suports porosos (scaffolds) mitjançant la tècnica solvent-casting particle-leaching emprant com a porògen sal, amb una grandària de porus que permet albergar cèl·lules en el seu interior, sobre els que s'han disposat, formant una estructura tipus sandvitx, membranes electrofilades. Aquestes membranes formen una estructura de fibres entrecreuades, deixant entre elles espais de grandària molt inferior a la grandària cel·lular, de mode que permeten el pas de nutrients i molècules a través d'elles, però actuen de barrera per a les cèl·lules impedint la seua migració a altres zones del sistema tridimensional. Aquest tipus d'estructures permeten simular, per exemple, l'arquitectura tubular renal, amb la zona porosa intersticial central i les dues capes epitelial i endotelial externes, que estarien en contacte amb l'orina i la sang, respectivament. Per a obtindre aquestes estructures, s'ha optat per emprar polímers de la família dels polièsters, en particular àcid polilàctic i poli(¿-caprolactona), així com la seua mescla i copolímers amb àcid poliglicòlic. Aquestes combinacions permeten ajustar la hidrofilicitat, i per tant la biodegradabilitat, la cinètica d'alliberació de fàrmacs i el comportament biològic, segons interesse. A més, l'ús de la tècnica d'electrospinning per al desenvolupament de les membranes, permet obtindre diferents diàmetres de fibra a partir de la modificació dels principals paràmetres de l'electrofilat, permetent també regular les propietats d'aquests materials. Finalment, per a estudiar l'alliberació de fàrmacs des del sistema anterior, les membranes electrofilades s'han carregat amb curcumina mitjançant dos mètodes diferents: a través del mètode d'emulsió i amb electrospinning coaxial, per a obtindre així diferents perfils d'alliberació. / [EN] The development of society has always been linked to scientific and technological advances. However, some of these advances have led to the appearance of new problems, especially of an ethical nature, giving rise to new associative movements opposed to them. An example of this is the use of animal experimentation, mainly in the field of medicine, and more specifically in the testing of drugs and implantable devices in contact with biological media. In this sense, the field of biomaterials and tissue engineering is working to find alternatives to animal experimentation. One of these alternatives is the development of in vitro models based on polymer supports for in vitro cell growth. These structures, moreover, could be used not only in drug testing or in vitro research to reduce the use of animals in experimentation, but also for tissue regeneration, simulating from simple tissues in which there is a single cell type, to more complex tissues from cell co-culture. Thus, in this thesis, a three-dimensional system with a stratified porous structure have been developed to allow both indirect cell co-culture and drug release assays. For this purpose, porous supports (scaffolds) have been obtained by means of the solvent-casting particle-leaching technique using salt as porogen, whose pore size allows cells to be housed in its interior, on which electrospun membranes have been arranged, forming a sandwich structure. These membranes form a structure of cross-linked fibers, leaving spaces between them that are much smaller than the cell size, so that they allow the passage of nutrients and molecules through them, but act as a barrier to the cells, preventing their migration to other areas of the three-dimensional system. This type of structure allows us to simulate, for example, the renal tubular architecture, with the central interstitial porous zone and the two outer epithelial and endothelial layers, which would be in contact with urine and blood, respectively. To obtain these structures, we have chosen to use polymers of the polyester family, in particular polylactic acid and poly(¿-caprolactone), as well as their blend and copolymers with polyglycolic acid. These combinations allow adjustment of hydrophilicity, and thus biodegradability, drug release kinetics and biological behavior, as desired. In addition, the use of the electrospinning technique for the development of membranes allows to obtain different fiber diameters by modifying the main electrospinning parameters, allowing also to regulate the properties of these materials. Finally, to study drug release from the previous system, the electrospun membranes have been loaded with curcumin by two different methods: through the emulsion method and with coaxial electrospinning, in order to obtain different release profiles. / Herrero Herrero, M. (2022). Desarrollo de andamiajes con porosidad estratificada basados en poliésteres como soportes en co-cultivo celular indirecto [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/190919

We introduce new oxygen- and moisture-proof polymer matrixes based on polyisobutylene (PIB) and its block copolymer with styrene [poly(styrene-block-isobutylene-blockstyrene), PSt-b-PIB-b-PSt] for the encapsulation of colloidal semiconductor nanocrystals. In order to prepare transparent and processable composites, we developed a special procedure of nanocrystal surface engineering including ligand exchange of parental organic ligands to inorganic species followed by the attachment of specially designed short-chain PIB functionalized with an amino group. The latter provides excellent compatibility of the particles with the polymer matrixes. As colloidal nanocrystals, we chose CdSe nanoplatelets (NPLs) because they possess a large surface and thus are very sensitive to the environment, in particular in terms of their limited photostability. The encapsulation strategy is quite general and can be applied to a wide variety of semiconductor nanocrystals, as demonstrated on the example of PbS quantum dots. All obtained composites exhibited excellent photostability, being tested in a focus of a powerful white-light source, as well as exceptional chemical stability in a strongly acidic media. We compared these properties of the new composites with those of widely used polyacrylate-based materials, demonstrating the superiority of the former. The developed composites are of particular interest for application in optoelectronic devices, such as color-conversion light-emitting diodes, laser diodes, luminescent solar concentrators, etc.