Block Copolymers
Mostrando 13-24 de 51 artigos, teses e dissertações.
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13. Molecular dynamics and formation of domains in block copolymers studied by high and low resolution NMR / Dinâmica molecular e formação de domínios em copolímeros em bloco estudados por RMN de alta e baixa resolução
The main objective of this dissertation is the use of NMR methods to characterize the phase separation and, to some extent, the dynamics of the molecular segments in block copolymers. In the first part, NMR Spin Diffusion methods were explored in order to evaluate their performance as well as the main experimental difficulties. For that, a reference tri-bloc
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 09/04/2012
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14. Nitroxide mediated and atom transfer radical graft polymerization of atactic polymers onto syndiotactic polystyrene
'Living' radical graft polymerization was employed to prepare graft copolymers with nitroxide-mediated arylated syndiotactic polystyrene as the backbone and polystyrene (PS), poly(p-methylstyrene) (PMS) and poly(methylmethacrylate) (PMMA) as branches. A two-stage process has been developed to synthesize the macroinitiator. First, syndiotactic polystyrene (sP
Brazilian Journal of Chemical Engineering. Publicado em: 2012-06
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15. Síntese e caracterização de copolímeros do tipo ABA para encapsulação de hemoglobina bovina
The use of biopolymers for the development of oxygen carriers has been extensively investigated. In this work, three different ABA triblock copolymers were synthesized and used to encapsulate purified bovine hemoglobin, using a double emulsion technique. The effect of polymer composition, homogenization velocity, and addition of a surfactant, on the protein
Química Nova. Publicado em: 2012
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16. ROMP como um método versátil para a obtenção de materiais poliméricos diferenciados
Ring Opening Metathesis Polymerization (ROMP) of cyclic olefins is a powerful transition metal-catalyzed reaction for syntheses of polymers and copolymers. The key feature of this reaction is the [2+2]-cycloaddition mechanism, with retention of the olefinic unsaturation in the polymer chain and occurrence of living polymerization. With the development of met
Química Nova. Publicado em: 2012
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17. Spectroscopic study of molecular dynamics and packing in organic semiconductors / Estudo espectroscópico da dinâmica molecular e empacotamento em semicondutores orgânicos
In this dissertation we present a study of the molecular dynamics and packing in organics semiconductor with different conjugated chains lengths using a of multi-techniques approach, in particular, Nuclear Magnetic Resonance (NMR), Wide Angle X-ray Scattering (WAXS), Differential Scanning Calorimetry (DSC), Raman spectroscopy, UV-Vis absorption and fluoresce
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 22/07/2011
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18. Micelas de copoli(oxialquileno)s: caracterizaÃÃo, encapsulaÃÃo e liberaÃÃo de fÃrmaco / Micelles of poly (oxialquileno) s: characterization, drug encapsulation and release
A solubilidade do fÃrmaco em Ãgua à um fator importante para sua eficÃcia. Entretanto, a maioria dos fÃrmacos apresenta baixa solubilidade em Ãgua. Para resolver este problema, copolÃmeros em bloco com propriedades surfactantes tÃm sido bastante investigados. O objetivo deste trabalho à investigar os copolÃmeros F87 (E62P39E62), E43B14E43 e suas mi
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 06/07/2010
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19. Water activity of aqueous solutions of ethylene oxide-propylene oxide block copolymers and maltodextrins
The water activity of aqueous solutions of EO-PO block copolymers of six different molar masses and EO/PO ratios and of maltodextrins of three different molar masses was determined at 298.15 K. The results showed that these aqueous solutions present a negative deviation from Raoult's law. The Flory-Huggins and UNIFAC excess Gibbs energy models were employed
Brazilian Journal of Chemical Engineering. Publicado em: 2010-03
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20. Propriedades mecânicas e morfologia de blendas de polipropileno com TPEs
Blendas de polipropileno e elastômeros termoplásticos (TPEs), estireno-b-butadieno-b-estireno (SBS) e estirenob- etileno-co-butileno-b-estireno(SEBS) foram preparadas com o objetivo de avaliar a influência do tipo e da concentração do elastômero nas propriedades mecânicas e na morfologia das blendas. Foram utilizados dois tipos de polipropileno, um ho
Publicado em: 2010
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21. Synthesis and characterization of thermo-responsive particles of poly(hydroxybutirate-co-hydroxyvalerate)-b-poly(N-isopropylacrylamide)
A new kind of thermo-responsive particles were prepared by the self-assembly technique, comprising poly(hydroxyvalerate-co-hydroxybutirate)-b-poly(N-isopropylacrylamide)/ (PHBHV-b-PNIPAAm) block copolymers. The hydrophilic part PNIPAAm was synthesized by Reversible Addition- Fragmentation chain Transfer (RAFT) polymerization. Particles with core-shell morpho
Brazilian Journal of Physics. Publicado em: 2009-04
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22. Copolímeros biodegradáveis com potencial uso como biomateriais / Biodegradable Copolymers with Potential use as Biomaterials
With the goal of obtaining a new class of biodegradable copolyesters with improved properties isosorbide succinate (IS) moieties were incorporated into the poly(L-lactide), PLLA, backbone. Three miscible block copolymers and one miscible random copolymer with both hydrophobic character and final degradation temperature higher than PLLA and possessing low ave
Publicado em: 2009
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23. Equilibrio de fases de sistemas contendo polimeros sinteticos e carboidratos em meio aquoso / Phase equilibrium of systems containing synthetic polymers and carbohydrates in aqueous medium
This work relates phase equilibrium of binary and ternary systems formed by aqueous mixtures of EO-PO block co-polymers of five different molar masses and EO/PO ratios, and maltodextrins of three different mean molar masses studied at 298.15 K. 25 Liquid-Liquid Equilibrium (LLE) phase diagrams for ternary systems at temperatures ranging from 288,15 to 308,15
Publicado em: 2009
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24. Synthesis and structural characterization of block and random low molecular weight copolymers composed of L-lactic acid and isosorbide succinate moieties
Resíduos de succinato de isosorbídeo foram incorporados na cadeia principal de poli(L-lactídeo) (PLLA) visando a obtenção de uma nova classe de polímeros biodegradáveis com propriedades melhoradas. Este artigo descreve a síntese e caracterização de quatro tipos de copolímeros de baixa massa molar. O copolímero I foi obtido da mistura dos monômer
Journal of the Brazilian Chemical Society. Publicado em: 2009