Na sociedade atual são múltiplos os problemas associados à visão, como a cataratas e o glaucoma. Ao longo dos anos, tem sido desenvolvida investigação em prol da qualidade de vida do Homem, nomeadamente no sentido de melhorar o tratamento e acompanhamento de casos clínicos. Porém, o maior desafio no tratamento das doenças oculares persiste. A capacidade de manutenção do nível terapêutico do fármaco no local de ação, durante o período de tempo necessário, continua a ser uma das dificuldades na ação terapêutica ocular. As gotas oftálmicas representam a maioria das formulações disponíveis no mercado, devido à sua fácil aplicação e aceitação pelo paciente, bem como ao custo acessível e à simplicidade de desenvolvimento e produção. Contudo, estas e outras formas de dosagem de administração tópica apresentam um curto tempo de residência, fazendo com que menos de 5% do fármaco penetre na córnea. Além disso, devido à fácil eliminação do volume da gota, em consequência da drenagem pelo canal nasolacrimal, da lacrimação e do pestanejar, são usadas concentrações elevadas de fármaco nestas formulações que podem causar efeitos secundários, sendo também necessário a aplicação frequente da formulação. Posto isto, é evidente a necessidade de desenvolver novas vias de administração de fármacos de aplicação ocular que superem os problemas apontados.Os insertos oculares surgem como uma nova aposta para a administração de fármacos no olho. Apesar de serem também de aplicação tópica, estes permitem aumentar a biodisponibilidade, tempo de residência e a atividade do fármaco, bem como a exatidão da dosagem e o controlo da taxa de libertação deste.Com esta dissertação pretendeu-se otimizar as condições de síntese (temperatura, tempo, quantidade de catalisador, quantidade e peso molecular de PEG) dos polímeros, PCL-PEG-PCL, que constituem o inserto que está a ser desenvolvido, bem como o estudo da influência desses parâmetros nas propriedades dos polímeros produzidos, nomeadamente o peso molecular. Também o scale up da reação é um dos objetivos do presente trabalho de investigação.Ao longo desta dissertação recorreu-se a diversas técnicas de caracterização, de forma a avaliar as propriedades químicas, físicas e térmicas dos polímeros sintetizados. A análise de ATR-FTIR permitiu caracterizar os reagentes e o catalisador da reação. Com a técnica RMN identificou-se a estrutura química dos polímeros e determinou-se, ainda, a sua conversão, peso molecular e percentagem de PEG. A análise SEC permitiu avaliar a distribuição do peso molecular dos polímeros sintetizados, bem como determinar o seu peso molecular. A análise TGA comprovou a estabilidade térmica dos polímeros produzidos. A análise DSC possibilitou conhecer algumas propriedades térmicas dos polímeros.Os resultados obtidos permitiram concluir que a percentagem e peso molecular de PEG são os parâmetros da reação que mais influenciam as propriedades dos copolímeros PCL-PEG-PCL, nomeadamente o peso molecular. Todavia, é necessário o controlo dos restantes parâmetros estudados (temperatura, tempo e quantidade de catalisador), de forma a assegurar um rendimento de reação de 100% e a obtenção de um polímero com polidispersividade próxima de 1, evitando a presença de monómeros e oligómeros que podem provocar reações oculares indesejadas.

Surface modification of poly(GMA-co -EDMA-co -MMA), whose synthesis was performed by copolymerization of 2,3-epoxypropyl methacrylate (GMA), methyl methacrylate (MMA), and ethylene glycol dimethacrylate (EDMA), was compared between aliphatic and aromatic substituted resorcarenes. The copolymer surface was modified by reacting with resorcarenes, and the vibrational properties of the modified copolymers were investigated via attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman spectroscopies in dry state at room temperature. Those analysis showed that only tetra(p -hydroxyphenyl)resorcarene was linked to the copolymer, the reaction was regioselective with the crown conformer. Additionally, quantification of incorporated macrocyclic was performed, specifically, the maximum fixation of resorcarene in the copolymer was 95% when employing two molar resorcarene excesses per glycidyl residue. The modification was carried out in both acidic and basic medium and it was established that the polymer is modified with the aromatic resorcarene only in basic medium, while the reaction in basic medium with aliphatic resorcarenes produces their corresponding tetrasodium salt.

Copolymers of aniline with anthranilic acid and two esters, ethyl and methyl anthranilate, were prepared through chemical synthesis using a variety of acids as the dopant. All polymers and copolymers were characterized by UV-Vis, Fourier transform infrared (FTIR) and Raman spectroscopies, as well as scanning electron microscopy. The data support the formation of variable amounts of phenazine-like structures due to ortho-coupling polymerization that competes with the para-coupling mode for the construction of the polymer backbone. The electrical conductivity and the solubility in a diversity of solvents were determined and correlated with the spectral data. The copolymers of aniline with anthranilic esters are more soluble than the corresponding polyanilines. In addition, the conductivity of the copolymer with methyl anthranilate doped with trifluoroacetic acid is of the same order of magnitude as that observed for the regular polyanilines. Overall, higher conductivities were obtained for all polymers and copolymers doped with hydrochloric acid and trifluoroacetic acid.

Abstract Two series of fluorinated copolymerized polyimide films with different dianhydride ratios were prepared via the conventional two-step method by using 4,4-oxydianiline(ODA) as the diamine monomer, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride(6FDA), 4,4'-oxydiphthalic anhydride(ODPA) and 3,3',4,4'- biphenyl tetracarboxylic dianhydride(BPDA) as the dianhydride monomer in N, N-dimethylacetamide. With the increase of 6FDA in the proportion of dianhydride, the tensile strength of the polyimide film showed a decreasing trend. This work provided a high performance film. The mass retention rate at 800°C was above 50%. The glass transition temperatures of the two films were 260 °C and 275 °C. The storage modulus of the two were 1500 MPa and 1250 MPa. The loss modulus were 218.70 MPa and 120.74 MPa. The transmittance of the film was 71.43%. The transmittance of fluorinated copolymerized polyimide films were significantly improved in the visible region of ultraviolet light, indicating that the polyimide film with high transmittance, high tensile strength, high heat resistance and high storage modulus was successfully prepared. It had an excellent application prospect in the field of flexible display.

The aim of this work is to evaluate the influence of octene-1 incorporation in the polybutadiene chain on the polymerization reaction and polymer characteristics. Thus, copolymerization of butadiene-1,3 with octene-1 using a Ziegler-Natta ternary catalyst based on neodymium was performed. The weight ratios of butadiene-1,3/α-olefin 100/0, 99/1, 97/3, 95/5, 90/10, 80/20 and 70/30 were evaluated. The copolymers were characterized by size exclusion chromatography (SEC), infrared spectroscopy (FTIR) and thermogravimetric analysis (TG). The results showed that the degradation temperature (Tmax) was not affected by the addition of alpha-olefin, while the thermal behavior has undergone significant changes. The polymer microstructure was not influenced by the increasing of octene-1 content. However, a tendency to molecular mass increase was observed with the increasing of octene-1 content. It was also observed a trend in reduction of the polymerization conversion as the octene-1 content increased.

Abstract New functional polymers will be prepared using alkyd resins having high solid content (environmentally friendly) and comb-type structural morphology. Different copolymers of hydroxyethyl acrylate and methyl methacrylate (HEMMA) were synthesized by solution polymerization using azo-bis-(isobutyronitrile) (AIBN) as initiator and dimethylformamide as a solvent. The proportions utilized of AIBN were 0.5 (HEMMA1), 1.0 (HEMMA2), 1.5 (HEMMA3) and 2.0 wt. % (HEMMA4). The conversion percentage of the reaction was higher than 90%. The formation of the copolymers was evidenced by infrared analysis, hydroxyl value, and nuclear magnetic resonance. The intensity of OH group adsorption increased with the molecular weight and hydroxyl value. The polydispersity index was lower than 1.5. All copolymers exhibited a stable region on viscosity at a shear rate between 0.1 and 10 s–1. The copolymers exhibited good thermal stability, flexibility, and adherence.