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Streptomyces are multicellular bacteria that grow as branched filaments and are best known for producing the majority of our antibiotics, many immunosuppressant and anticancer compounds. Unfortunately their multicellular life style creates many problems for efficient industrial production. In a bioreactor, depending on the environment and the genetics, it can grow quickly as dispersed mycelia or aggregate in slow growing pellets. Either morphology has advantages and disadvantages, which can be product specific. For my thesis I studied the mechanism by which these filaments can aggregate into dense pellets. I found a small gene cluster that produces poly-1,6-N-acetylglucosamine, a bacterial glue which binds neighboring cells and required for pellet formation in S. coelicolor. Subsequently we can use these genes to control the morphology of streptomycetes in a liquid environment, tailoring it for production. My work has given us new insights in the mechanims through which streptomycetes aggregate, but also has the potential to make streptomycetes a more favorable host for industial production.

New aromatic poly-1,2,4-triazoles and poly-1,3,4-oxadiazoles are studied as thermally stable membrane materials. Various groups were introduced onto the pendant phenyl groups of poly-1,2,4-triazoles. Glass transition temperature, degradation temperature, and cold crystallization behavior were studied as a function of these groups. Cold crystallization appeared to be highly sensitive to macromolecular regularity. The solubility of poly-1,3,4-oxadiazoles was highly improved upon incorporation of 5-t-butylisophthalic, 1,1,3-trimethyl-3-phenylindane, 4,4-(2,2-diphenyl) hexafluoro propane, and diphenyl ether groups into the polymeric main chain, whereas the high glass transition temperatures and degradation temperatures typical for aromatic poly-1,3,4-oxadiazoles were maintained.

Os catalisadores lantanídicos são muito eficientes na polimerização estereoespecífica de dienos, principalmente aqueles à base de neodímio. Neste trabalho será apresentado o estudo da polimerização do 2-metil, 1,3-butadieno com catalisadores à base de neodímio, utilizados comercialmente na polimerização do 1,3-butadieno. Foi estudado o efeito da temperatura, do tipo de alquilalumínio e da concentração de catalisador. As reações foram realizadas em reator de aço inox sob atmosfera inerte, usando como solvente o hexano e uma concentração de 2-metil, 1,3-butadieno de 12%. Foram obtidos polímeros com massas molares na faixa de 1,0 a 1,5 × 105 e teor de unidades repetitivas cis em torno de 97%. The rare earth metals catalysts are very efficient in stereospecific polymerization of dienes, especially those of neodymium. This paper reports on the polymerization of 2-methyl, 1,3-butadiene with catalysts of neodymium, used commercially in polymerization of 1,3-butadiene. Effects were studied from the temperature, type of alkylaluminum, and from the concentration of catalyst. The reactions were carried out in a stainless steel reactor under an inert atmosphere, using hexane as the solvent and a concentration of 12% of 2-methyl, 1,3-butadiene. Polymers were obtained with molecular weight from 1.0 to 1.5 × 105, with ca. 97% of cis repeating units.

International audience; Reoplex(R) 346, a low number-average molecular weight ((M) over bar(n)) poly 1,3-butylene adipate-frequently used as plasticizer in PVC-based cling-films-was studied by H-1 and quantitative C-13 NMR. It was found that Reoplex(R) results from the linear polyesterification of adipic acid (A) by an excess of butane 1,3-diol (B) with a (A/B) molar ratio of 0.88 giving a polyester having a number-average degree of polymerization (n) and an absolute (M) over bar(n) of 15.7 and 1600 g/mol, respectively. As primary alcohol function is more reactive than secondary alcohol, Reoplex(R) chain-ends are made up of 28.6% of primary alcohol and 71.4% of secondary alcohol

Two reaction routes for the preparation of aromatic poly-1,3,4-oxadiazoles and poly-1,2,4-triazoles are studied and their influence on the physical properties, i.e., inherent viscosity, glass transition, degradation temperature, and film integrity of the final products are discussed. Aromatic poly-1,3,4-oxadiazoles are prepared by means of a polycondensation reaction of terephthaloyl chloride and isophthalic dihydrazide yielding a precursor polymer, poly(p, m-phenylene) hydrazide, which is converted into the corresponding poly-1,3,4-oxadiazole by means of a cyclodehydration reaction. Poly-1,3,4-oxadiazoles are also prepared by means of a polycondensation reaction between terephthalic and isophthalic acid and hydrazine yielding poly-1,3,4-oxadiazoles with higher inherent viscosities. Flexible poly-1,3,4-oxadiazole films are obtained only if the inherent viscosities of the polymers used are higher than 2.7 dL/g. The thermal stability is found to increase with increasing content of p-phenylene groups in the polymer backbone. Aromatic poly-1,2,4-triazoles are prepared using polyhydrazides with alternating para- and meta-phenylene groups and poly-1,3,4-oxadiazoles with a random incorporation of para- and meta-phenylene groups in the main chain as precursor polymers. The glass transition temperatures are found to increase with increasing content of p-phenylene groups in the main chain of these polymers. Cold crystallization is observed only for the alternating polymer.