Block Copolymers
Mostrando 25-36 de 51 artigos, teses e dissertações.
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25. Estudo da tenacificação do poliestireno com elastômeros butadiênicos / Polystyrene toughening by butadiene elastomers
This Dissertation describes a study about the toughening of polystyrene with different types of polybutadiene (high-cis, low-cis and styrene - butadiene diblock or triblock copolymers). These materials (High Impact of PolyStyrene HIPS) were performed by melt blending. The mechanical properties (hardness, tensile strength and impact strength); morphology and
Publicado em: 2009
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26. Protein decorated Nanoparticules : Small Unilamellar Lipid Vesicules and Block Copolymers Micelles. / Nanoparticules Décorées par des Protéines : Vésicules Lipidiques Unilamellaires et Micelies à Base de Copolymères à Blocs
The formation of protein Annexin-A5 decorated (bio-functionalized) nanoparticles is of particular interest in micelle-mediated target drug delivery, in vivo magnetic resonance imaging, or controlled fabrication of biochips. This work describes an easy access to the synthesis and manipulation of block copolymer nano-objects exhibiting binding ability for the
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 03/07/2008
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27. Síntese e caracterização de dispersões aquosas de poliuretanos à base de copolímeros em bloco de poli(glicol etilênico) e poli(glicol propilênico)
Non-polluting polyurethane aqueous dispersions, with 40% of solids content, were synthesized based on block copolymers of poly(ethylene glycol) and poly(propylene glycol) (PEG-b-PPG), with PEG hydrophilic segments content of 7 and 25%, poly(propylene glycol) (PPG), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI), and hydrazine. Different form
Química Nova. Publicado em: 2008
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28. Homopolimerização e copolimerização via radical livre controlada por radicais nitroxidos / Nitroxide mediated radical homopolymerization and copolymerization
Controlled/living radical polymerization (CLRP) is one of the most rapidly developing areas of polymer science and engineering. The ability to prepare well-defined block and graft copolymers, gradient and periodic copolymers, stars, combs, polymer networks, end-functional polymers and many other materials by free-radical mechanisms is perhaps the main reason
Publicado em: 2008
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29. Investigação experimental e computacional da polimerização via radical livre controlada em presença de radicais nitroxido (NMRP) utilizando-se iniciadores difuncionais / Experimental and computational investigation of nitroxide mediated radical polymerization (NMRP) using di-functional initiators
Controlled/Living Free Radical Polymerization (LFRP) is one of the most important techniques for production of polymeric materials with good control of the microstructure (e.g., narrow molecular weight distributions). Such properties can also be achieved via ionic polymerizations, but being a free radical polymerization process, LFRP is much less sensitive t
Publicado em: 2008
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30. Síntese de copolímeros em bloco com propriedades líquido cristalinas
The principal techniques for the synthesis of liquid crystalline block copolymers are reviewed. The syntheses are done by living/controlled free radical chain polymerization. The copolymers display an amorphous continuous phase and a discontinuous liquid crystalline phase (LC). The presence of oxypropylenic segments disturbs the range of mesophase transition
Química Nova. Publicado em: 2007-06
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31. Transições de fase em polimeros liquido-cristalinos de cadeia lateral / Phase transitions in side-chain liquid-cristaline polmers
Polymeric liquid crystals are materials that combine properties of both polymers and liquid crystals. These polymers can be thought as block copolymers made of ftexible and rigid molecular blocks. As in flexible block copolymers, the macrophase separation originated from the repulsion between different blocks is frustrated by the connectivity constraint impo
Publicado em: 2007
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32. Preparation and rheological characterization of nanocomposites of styrenic polymers. / Obtenção e caracterização reológica de nanocompósitos de polímeros estirênicos.
Neste trabalho foram preparados nanocompósitos de polímeros estirênicos com argilas organofílicas. Os polímeros estudados foram o poliestireno (PS), um copolímero tribloco de poliestireno-b-polibutadieno-b-estireno (SBS) e quatro copolímeros tribloco de poliestirenob- poli(etileno-co-butileno)-b-estireno (SEBS), sendo um deles modificado com anidrido
Publicado em: 2007
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33. Estudo do efeito da adição de poli(glicol etilênico-b-glicol propilênico) na formação de dispersões aquosas poliuretânicas à base de poli(glicol propilênico) / Study of the effect of the copolymer poly(ethylene glycol-co-propylene glycol) addition on the polyurethane based poly(propylene glycol) aqueous dispersions formation
Non-polluting and poly(urethane-urea) aqueous dispersions based on poly(propylene glycol) (PPG) and block copolymers of poly(ethylene glycol-b-propylene glycol) (EG-b-PG) containing 7% of ethylene glycol repeating units, were produced in an innovative way. The poly(urethane-urea)s were prepared, in two steps, by the prepolymer method. In the first step, anio
Publicado em: 2007
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34. Compatibilizing effect of post-consumer high density polyethylene in blends with polyamide-6 / Efeito compatibilizante do polietileno de alta densidade pos-consumo em blendas com poliamida-6
Polymer blends are commonly immiscible, due to the small entropy of mixture, and incompatible, caused by the absence of intermolecular interactions between the phases, resulting in poor mechanical properties. The addition of block or graft copolymers is an alternative way to improve the adhesion at the interface and to reduce the interfacial tension. In this
Publicado em: 2007
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35. Desenvolvimento de um modelo matematico mais rigoroso para polimerização radicalar controlada mediada por radicais nitroxido de estireno / Development of more detailed mathematics model for nitroxide mediated living free radical polymerization (NMRP)
Living Free-Radical Polymerization (LFRP) has been target of much attention in the last years, because it allows getting polymers with a highly controlled microstructure, with narrow distribution of the average molecular weights and polydispersity (PDI) close to unit, and with complex molecular structures (e.g. pure block copolymers), with different architec
Publicado em: 2007
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36. Filmes de Langmuir e Langmuir-Blodgett (LB) de azopolímeros com controle do tamanho da cadeia e posição dos cromóforos / Langmuir and Langmuir-Blodgett (LB) films of azopolymers with controlled chain-length and chromophores position
Azopolímeros apresentam propriedades de fotoisomerização, úteis para confecção de memórias ópticas, que dependem da arquitetura molecular do azopolímero e do filme formado a partir dele. Neste trabalho foram sintetizados polímeros com arquitetura molecular controlada, usando os azomonômeros [4-(N-etil-N-2-(metacriloxietil)) amino-2-cloro-4-nitroaz
Publicado em: 2006