The complex [Ti3(O)(Cl)(ONep)9] and two iron(II)-containing products, [Fe4Cl8(thf)6] and [Fe2Cl3(thf)6][FeCl4], were synthesized by a redox reaction involving [Ti3(OiPr)11][FeCl4] and neopentanol; the structures of compounds [Ti3(O)(Cl)(ONep)9] and [Fe2Cl3(thf)6][FeCl4] have been confirmed by X-ray diffraction methods. Variable-temperature 1H NMR analysis of [Ti3(O)(Cl)(ONep)9] revealed signals for three non-equivalent neopentoxides in the 1:1:1 integration ratio, indicating the maintenance of the trinuclear structure in solution. Alkoxide [Ti3(O)(Cl)(ONep)9] was employed as initiator in both bulk and solution polymerization of ε-caprolactone (ε-CL) at various temperatures, monomer/initiator molar ratios and reaction times. [Ti3(O)(Cl)(ONep)9] produced poly(ε-caprolactone) in high yields, with molecular weights ranging from 7100 to 9800 g mol-1 and PDI (polydispersity index) values between 1.3 to 1.5. The reactivity of [Ti3(O)(Cl)(ONep)9] in the ring-opening polymerization (ROP) of ε-CL was compared to those of [Ti3(OiPr)11][FeCl4] and [Ti(OiPr)4]. The better polymerization reactivity shown by [Ti3(O)(Cl)(ONep)9] seems to be associated with structural features, as well as with the stronger Lewis basicity of -ONep over -OiPr ligands and the maintenance of the trimetallic structure in the reaction media.

The activity of the heterometallic alkoxide [FeCl{Ti2(OiPr)9}] (1) towards polymerization of rac-lactide (rac-LA) and ε-caprolactone (ε-CL) was investigated in toluene solution and in bulk at various temperatures, monomer/heterometallic alkoxide molar ratio and reaction times. The alkoxide 1 was active in solution for ε-CL and in bulk for both monomers. Polymers were obtained in good yields with molecular weights ranging from 3890 to 15000 g moL-1 and polydispersity indexes (PDI) values varying from 1.3 to 2.5. Based on the 1H nuclear magnetic resonance (NMR) end-group analysis of polymers, a coordination-insertion mechanism was suggested for both monomers. The average number of growing chains per molecule of initiator (4 to 5 for rac-LA and 7 to 8 for ε-CL) indicates that both bridging and terminal isopropoxides are active initiating groups. Kinetic studies with ε-CL indicated that the polymerization rate is first order with respect to monomer concentration. The catalytic properties of 1 were compared to those found for other titanium(IV) and iron(II) complexes using ε-CL as a model monomer.

A contaminação dos recursos hídricos é um dos maiores problemas ambientais da atualidade. Dentre as várias fontes poluidoras, destacam-se as indústrias têxteis, por serem fontes geradoras de grandes volumes de efluentes, muitas vezes tratados de maneira ineficiente. A principal causa do grande impacto ambiental decorrente deste descarte é a presença dos corantes, tais como os compostos do tipo azo, que podem gerar subprodutos de caráter carcinogênico e/ou mutagênico, ou como os de base antraquinona, que são muito resistentes à degradação natural e portanto persistem no efluente por um longo tempo. O objetivo do presente trabalho consiste na utilização de processos foto-Fenton assistidos por luz artificial e solar, utilizando ferro imobilizado em esferas de quitosana reticulada com glutaraldeído, para promover a degradação do corante reativo Azul QR-19, de base antraquinona, em solução aquosa. As esferas obtidas apresentaram tamanho regular com diâmetro de 4,0 mm. Os resultados demonstraram 90% de descoloração do sistema em 180minutos e redução de 60% do teor de carbono orgânico total (COT), para o sistema foto-Fenton utilizando luz artificial. Para o sistema fotoassistido com luz solar, a descoloração foi integralmente obtida em 120 minutos com 70% de redução do teor de COT. Foi observado que o ferro permaneceu na matriz após o tratamento, possibilitando sua reutilização.

The contamination of water resources is one of the greatest environmental problems today. Among the polluting sources are the textile industries due to the production of large volumes of effluent, often treated inefficiently. The main reason for the environmental impact of the rejected materials is the presence of dyes such as azo reactive compounds that can generate by-products with carcinogenic and mutagenic effects. They may also include anthraquinone type compounds, which are highly resistant to degradation and persist in the effluent for a long time. The purpose of this study is the use of photo-Fenton processes assisted by artificial or solar light, using immobilized iron on chitosan beads, crosslinked with glutaraldheyde, for the antraquinone type compound Blue QR-19 standard dye degradation in aqueous solutions. The obtained spheres showed a regular size and 4.0 mm diameter. The results showed 90% discolouration of the system within 180 minutes and a 60% total organic carbon (TOC) reduction for the photo-Fenton system using artificial light. For the system using sunlight, the total discolouration was achieved in 120 minutes and the TOC value decreased 70%. Also observed was that iron remained in the polymeric matrix after the treatment, thus allowing reuse.

Micropartículas de poli(3-hidroxibutirato-co-3-hidroxivalerato) (PHBV) contendo um fármaco modelo hidrofílico, o cloridrato de metformina (MH), foram obtidas pela técnica de emulsão múltipla/evaporação do solvente. Diversas formulações foram preparadas, com o objetivo de investigar a influência de cada composição sobre a eficiência de encapsulação (EE). O resultado mais elevado de EE (9,76%) foi verificado quando da simultânea alcalinização e adição de NaCl na fase aquosa externa da formulação. O estudo por MEV das micropartículas revelou morfologia esférica e superfície rugosa. As intensidades de difração cristalina para as micropartículas contendo o MH foram menores do que aquelas observadas para a mistura física. Os resultados obtidos por IVTF sugerem que nenhuma ligação química foi formada entre o polímero e o fármaco. A avaliação por análise térmica indica o surgimento de interações favoráveis entre MH e PHBV. O estudo de liberação in vitro demonstrou a influência do PHBV no perfil de dissolução do MH.

Poly(3-hydroxybutirate-co-3-hydroxyvalerate) (PHBV) microparticles containing a water-soluble model drug, metformin hydrochloride (MH), were obtained by a double emulsion/solvent evaporation technique. Several formulations were prepared in order to investigate the influence of each composition on the encapsulation efficiency (EE). The highest value of EE (9.76%) was obtained using simultaneously pH alkalinization and NaCl addition in the external water phase of the formulation. SEM study revealed a spherical morphology and a rough surface. The crystalline diffraction intensities for the MH-loaded microparticles were lower than that verified for the physical mixture. FTIR results suggested that no chemical bond between the polymer and the drug was formed. Also thermal analyses indicated a favorable interaction between MH and PHBV. In vitro drug release demonstrated the influence of the PHBV on the dissolution profile of MH.

No presente trabalho foram preparados poliuretanos (PUs) segmentados. Primeiramente foi obtido um pré-polímero (PP) a partir da reação de 2,4 e 2,6 - diisocianato de tolileno (TDI) e poli(épsilon-caprolactona) diol (PCL). A PCL é um poliéster biodegradável que constituiu o segmento flexível do PU. O segmento rígido foi constituído por unidades uretânicas provenientes da ligação entre as extremidades isocianato do PP e as hidroxilas do extensor de cadeia: 1,4 - butanodiol (BDO), ou sacarose (SAC), ou glicose (GLY). Foram avaliadas as propriedades mecânicas e dinâmico-mecânicas dos poliuretanos obtidos e estas foram correlacionadas com os parâmetros estruturais. Os resultados foram justificados com base na intensidade das interações de hidrogênio, na mistura de fases, no volume dos extensores cíclicos e na presença de ligações cruzadas. Estes PUs estão sendo estudados com vistas à preparação de materiais biodegradáveis com propriedades mecânicas úteis.

Segmented polyurethanes containing polycaprolactone as soft segment were prepared taking into account the biodegradable character of this compound. The hard block was produced by the reaction between tolylene diisocyanate and a chain extender (1,4 butanediol, sucrose or glucose). The mechanical and dynamical properties were evaluated as a function of the contents of rigid blocks. The results were analyzed on the basis of the intermolecular interactions, mainly H bonds, phase mixture, volume of cyclic chain extenders and crosslinking. These polyurethanes are being studied aiming at the preparation of biodegradable materials with useful mechanical properties.

O parâmetro de solubilidade de poliuretanos segmentados foi determinado através de ensaios de inchamento no equilíbrio, tratando-se os dados pela teoria de Flory-Rehner. O segmento flexível dos poliuretanos foi constituído por blocos de oligobutadieno e o segmento rígido foi formado pela reação entre di-isocianato de tolileno e os extensores de cadeia 1,3-propanodiol; 1,4-butanodiol; 1,6-hexanodiol e 2, 2'-di-hidroxi-isopropil N, N'anilina. O teor em segmento rígido para os polímeros provenientes dos extensores alifáticos ficou na faixa de 25,1% a 28,3%, enquanto que, nos polímeros estendidos com o extensor aromático, foi de 32,6%.

The solubility parameter of a series of segmented polyurethanes was determined through equilibrium swelling experiments, using the Flory-Rehner theory. The soft segment of the polyurethanes was oligobutadiene and the hard block was formed through the reaction of tolylene diisocyanate with propanediol, butanediol, hexanediol or 2, 2' dihydroxy isopropyl N, N' aniline. The hard segment content in all polymers was about the same for the aliphatic extenders (25.1% to 28.3%) and 32.6% for the aromatic one.

Poli(metacrilato de metila) (PMMA) de massa molar controlada foi sintetizado, em solução de tolueno, utilizando peróxido de benzoíla como iniciador e 1-dodecanotiol (DDM) como agente de transferência de cadeia. O efeito da concentração de DDM sobre a massa molar do PMMA foi investigado. Copolímeros de metacrilato de metila e ácido metacrílico, P(MMA-MAA), foram sintetizados a partir da hidrólise parcial de homopolímeros de metacrilato de metila com variadas massas molares. Utilizando uma técnica inédita na literatura para a síntese de ésteres poliméricos, foi realizada a reação das unidades ácidas do P(MMA-MAA) com álcoois de cadeia longa, na presença de 1,3-diciclo-carbodiimida e 4-dimetilamino-piridina, que produziu copolímeros contendo longos segmentos hidrocarbônicos pendentes, tais como o poli(metacrilato de metila-co-metacrilato de hexadecila).

Controlled molecular weight poly(methyl methacrylate) (PMMA) was synthesized in toluene solution using benzoyl peroxide/dodecanethiol as initiator/chain transfer agent system. The effect of the thiol concentration on the molecular weight of PMMA was investigated. Methyl methacrylate and methacrylic acid copolymers, P(MMA-MAA), were prepared by partial hydrolysis of the PMMA homopolymers of different molecular weights. By reacting the acid residues of the copolymers with long chain alcohols, in the presence of 1,3-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, copolymeric esters of PMMA with long chain substituents, such as hexadecyl, were obtained. This technique has not been reported in the literature for the synthesis of PMMA esters.