Calcinação e estabilidade térmica de Sílicas mesoporoas preparadas com Pluronic P123

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Utilização de uma matriz híbrida orgânica-inorgânica na dinâmica de liberação controlada de fármacos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fine-tuning of a nanostructure, swelling, and drug delivery profile by blending ureasil-PEO and ureasil-PPO hybrids

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ureasil-polyether hybrid blend with tuneable hydrophilic/hydrophobic features based on U-PEO1900 and U-PPO400 mixtures

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

New biphasic mono-component composite material obtained by partial oxypropylation of bacterial cellulose

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Controlled swollen and drug release from urea-cross-linked polyether/siloxane hybrids

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Síntese de aluminas macro-mesoporosas pelo método sol-gel acompanhado de separação de fases

Pós-graduação em Química - IQ

Aluminium- und Yttrium-Initiatoren für die koordinative Ringöffnungspolymerisation von Propylenoxid

Zielsetzung ist der synthetische Zugang zu metallorganischen Verbindungen, die Propylenoxid koordinativ polymerisieren und deren Aktivität sich durch gezielte Variation der sterischen oder elektronischen Eigenschaften kontrollieren läßt. Zur Bearbeitung dieser Aufgabe werden zwei verschiedene Klassen von Komplexen synthetisiert und charakterisiert: Vorwiegend durch Salzmetathese werden mehrere Yttriumamide der allgemeinen Formel Y(NRR´)3(THF)x erhalten. Dabei erfolgt eine Diskussion der Auswirkungen sterischer und elektronischer Variation der beiden Amido-Substituenten R und R´, die sich in der Bildung von „at“-Komplexen, Lösungsmitteladdukten und größeren Aggregaten äußern. Durch Alkaneliminierung wird eine umfassende Reihe von Aluminiumkomplexen methylen- und thioverbrückter Bisphenolatoliganden dargestellt. Die Verbindungen besitzen unter Ausschluß zusätzlicher Basen dimere oder mehrkernige Strukturen, deren Diskussion schwerpunktsmäßig anhand ihres Verhaltens in Lösung erfolgt. Die Aluminiumkomplexe werden in anschließenden Reaktionen zu Lösungsmitteladdukten und Aluminaten umgesetzt.Die Yttriumamide initiieren die Ringöffnungspolymerisation von Propylenoxid bei Temperaturen von 60 oder 80 °C. Die Polymerisation erfolgt nach einem koordinativen Mechanismus, eine zu niedrige Katalysatoreffizienz schließt jedoch die Yttriumamide als Vorläufer zu definierten „single site“-Katalysatoren aus. Mit der Kombination aus neutralen Aluminiumkomplexen mit den entsprechenden Aluminaten verläuft die Ringöffnungspolymerisation von Propylenoxid bei Raumtemperatur schnell und kontrolliert. Es läßt sich ein prinzipiell neuer Mechanismus belegen, bei dem die Polymerisation unter synergistischer Wirkung eines Aluminiumphenolato-Komplexes mit dem korrespondierenden „at“-Komplex erfolgt.

Aditivo polimérico derivado de fonte renovável para aplicação em cimento asfáltico de petróleo

This study evaluated the effects of incorporating an additive from an agro-industrial residue, after some chemical modification reactions, to petroleum asphalt cement (CAP) through the polymerization reaction of a viscous polyol obtained by bagasse biomass oxypropylation reaction sugarcane with anhydrides. The polyol is obtained by biomass oxypropylation reaction with propylene oxide, the reaction was performed in an autoclave sealed with pressure and temperature control using 25 mL of OP for every 5 grams of biomass 200°C, which time reaction was two hours. The reaction is revealed by varying the system pressure, initially at atmospheric pressure to reach a maximum pressure value and its subsequent return to atmospheric pressure. For the choice of the most suitable reaction time for polymerization of the polyol with pyromellitic anhydride, the reaction was also conducted in an autoclave sealed with temperature controller (150 ° C) using 20 g of polyol, 1 g of sodium acetate (catalyst) and 8 g of pyromellitic anhydride with the times 30 and 60 minutes. The polymerized materials with different times were characterized by determining the relative viscosity and percentage content of extractable in cyclohexane / ethanol. Given the results with the polymerized material 30 minutes showed the lowest percentage content of extractives and an increased viscosity relative indicating that this time is highlighted with respect to time 60 minutes, because the material is possibly in the form of a crosslinked polymer. Given the choice of time of 30 minutes other polymerization reactions were performed with various anhydrides and other conditions employed different proportions by mass of polyol anhydrides we were referred to as condition I (20 g anhydride and 8 g of polyol), II (20 g anhydride and 20 g of polyol) and III (8 g anhydride and 20 g of polyol). The FTIR spectra of polymeric materials with different polymerization conditions used to prove the occurrence of chemical modification due to the appearance of a characteristic band ester groups (1750 cm-1) present in the polymerized material. He chose to work with the condition III, as is the condition which employs a larger amount of polyol, and even with the smaller amount of anhydride used FTIR spectra revealed that the polymerization reaction was performed. Among the various anhydrides (phthalic, maleic and pyromellitic) of the different conditions used that stood out before the solubility test with solvents analyzed was polymerized material with pyromellitic anhydride because the polymerized material likely in the form of a crosslinked polymer because it was insoluble or poorly soluble in the solvents tested. Polymerization of the polyol with pyromellitic anhydride using condition III, that is, BCPP30, CSPP30, PCPP30 e BCPPG30, provided an increase in thermal stability relative to material in the form of polyol. Applicability tests concerning the incorporation of 16% m / m BCPP30, CSPP30, PCPP30 e BCPPG30 additive in relation to the mass of 600 g CAP showed through characterization tests used, softening point, elastic recovery and marshall dosage, it is possible to use BCPP30 as an additive the conventional CAP, because even with the incorporation of this new additive modified CAP met the specifications of the appropriate standard.

Crystallization and morphology of poly(ethylene oxide-b-lactide) crystalline-crystalline diblock copolymers

The crystallization behaviors and morphology of asymmetric crystalline-crystalline diblock copolymers poly(ethylene oxide-lactide) (PEO-b-PLLA) were investigated using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and microscopic techniques (polarized optical microscopy (POM) and atomic force microscopy (AFM)). Both blocks of PEO5-b-PLLA(16) can be crystallized, which was confirmed by WAXD, while PEO block in PEO5-b-PLLA(30) is difficult to crystallize because of the confinement induced by the high glass transition temperature and crystallization of PLLA block with the microphase separation of the block copolymer.

Synthesis and Characterization of Coil-Rod-Coil Triblock Copolymers Comprising Fluorene-Based Mesogenic Monodisperse Conjugated Rod and Poly(ethylene oxide) Coil

A series of coil-rod-coil triblock copolymers (i.e., F3T8EO8, F3T8EO17, F3T8EO45, and F3T8EO125) with a mesogenic monodisperse conjugated oligomer comprising 3 fluorene, 8 thiophene, and 2 phenyl units as the rod and poly(ethylene oxide) (PEO) as the coil were synthesized. A reference compound, that is F3T8ME2, with the identical rod but without PEO was also prepared for comparison. The volume fraction of PEO (f(PEO)) was 0, 0.16, 0.28, 0.50, and 0.73 for F3T8ME2, F3T8EO8, F3T8EO17, F3T8EO45, and F3T8EO125, respectively. It was found that the introduction of PEO into the triblock copolymers encouraged the formation of H-type aggregation and f(PEO)-dependent highly ordered mesophases while f(PEO) < 0.73. For F3T8ME2, only nematic mesophase was observed. In contrast, F3T8EO8 and F3T8EO17, with f(PEO) of 0.16 and 0.28, respectively, are smectic A (SA) mesomorphism.

Compositional differences of propylene-ethylene block copolymers manufactured by degradation and hydrogenation techniques

The purpose of the present work is to investigate the compositional difference of polypropylene-polyethylene block copolymers (PP-b-PE) manufactured industrially by the process of degradation and hydrogenation, respectively. Each of the PP-b-PE copolymers was fractionated into three fractions with heptane and chloroform. The compositions of the three fractions were characterized by C-13 nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy, as well as differential scanning calorimetry (DSC) and thermal fractionation. The results showed that the Chloroform-soluble fraction was amorphous ethylene-propylene rubber, and the content of the rubber in PP-b-PE manufactured by hydrogenation was less than that by degradation. The degree of crystallinity of the chloroform-insoluble fraction of the PP-b-PE manufactured by hydrogenation is higher than that of by degradation.

Isothermal crystallization kinetics of PEO in poly(ethylene terephthalate)-poly(ethylene oxide) segmented copolymers. I. Effect of the sofi-block length

The isothermal crystallization kinetics of poly(ethylene oxide) (PEO) block in two poly(ethylene terephthalate) (PET)-PEO segmented copolymers was studied with differential scanning calorimetry. The Avrami equation failed to describe the overall crystallization process, but a modified Avrami equation, the Q equation, did. The crystallizability of the PET block and the different lengths of the PEO block exerted strong influences on the crystallization process, the crystallinity, and time final morphology of the PEO block. The mechanism of nucleation and the growth dimension of the PEG block were different because of the crystallizability of time PET block and the compositional heterogeneity. The crystallization of the PEO block was physically constrained by the microstructure of time PET crystalline phase, which resulted in a lower crystallization rate. However, this influence became weak with the increase in the soft-block length. (C) 2000 John Wiley & Sons, Inc.

Nonisothermal crystallization kinetics of ethylene terephthalate-ethylene oxide segmented copolymers with two crystallizing segments

The nonisothermal crystallization behavior of ethylene terephthalate-ethylene oxide segmented copolymers has been studied by means of differential scanning calorimetry (DSC). The kinetics of ET-EO segmented copolymer under nonisothermal crystallization conditions has been analyzed by the Ozawa equation. During the crystallization of the high-T-m segments (PET), the low-T-m segments (PEO) act as a noncrystalline diluent, the crystallization behavior of PET obeys the Ozawa theory. When the PEO segments begin to crystallize, the PET phase is always partially solidified and the presence of the spherulitic microstructure of PET profoundly influences the crystallization behavior, which results in that the overall crystallization process does not obey the Ozawa equation. (C) 2000 Elsevier Science Ltd. All rights reserved.