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156. ADMET reactions in miniemulsion

Author

Cardoso, Priscilla B., primary, Musyanovych, Anna, additional, Landfester, Katharina, additional, Sayer, Claudia, additional, Araújo, Pedro H. H., additional, and Meier, Michael A. R., additional

Published
2014
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163. Poly(3-hydroxybutirate- co-3-hydroxyvalerate)-Polystyrene Hybrid Nanoparticles via Miniemulsion Polymerization.

Author

Leimann, Fernanda Vitória, Costa, Cristiane, Gonçalves, Odinei Hess, Musyanovych, Anna, Landfester, Katharina, Sayer, Claudia, and de Araújo, Pedro Henrique Hermes

Subjects
NANOCOMPOSITE materials, POLYHYDROXYBUTYRATE, VALERATES, POLYSTYRENE, FOURIER transform infrared spectroscopy, DIFFERENTIAL scanning calorimetry
Abstract

Hybrid polymer nanoparticles were obtained by miniemulsion polymerization of styrene with poly(3-hydroxybutirate-co-3-hydroxyvalerate) (PHBV). Lower polymerization rates were obtained with the gradual addition of PHBV. These results were represented by simulations using a mathematical model that takes into account grafting reactions between the growing polymeric chains and PHBV double bonds (reduced molar mass). Hybrid nanoparticles presented average diameters of up to 113 nm and grafting yield of 94.4%. The hybrid fractions obtained by Selective Soxhlet Extraction were characterized with Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry and Transmission Electron Microscopy. Blend nanoparticles were used to confirm the hybrid formation. [ABSTRACT FROM AUTHOR]

Published
2016
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184. Decrease of methyl methacrylate miniemulsion polymerization rate with incorporation of plant oils.

Author

Costa, Cristiane, Wagner, Manfred, Musyanovych, Anna, Landfester, Katharina, Sayer, Claudia, and Araújo, Pedro H. H.

Subjects
METHYL methacrylate, POLYMERIZATION, VEGETABLE oils, NANOPARTICLES, TRIGLYCERIDES
Abstract

Miniemulsion polymerization reactions of methyl methacrylate were conducted in the presence of plant oils, in order to investigate the effect of different types (linseed oil and andiroba oil) and amounts of oils on the polymerization reaction rates and on the molecular weight of the produced polymers. A decrease in the reaction rate, that was proportional to the number of double bonds present in the triglycerides, was observed. Polymers with lower molecular weights were obtained when triglycerides with higher number of double bonds were used. The experimental data were analyzed with a mathematical model developed to represent the kinetics of these reactions, including the kinetic mechanisms associated to free radical miniemulsion polymerization with an oil-soluble initiator, and the model was able to predict the variation in the polymerization reaction rate depending on the type and amount of the plant oil. Practical applications: Plant oils can be incorporated to polymer latex by free radical miniemulsion polymerization partially substituting petroleum derived monomers. As most plant oils are highly hydrophobic, they act as co-stabilizers preventing diffusional degradation increasing the stability of the colloidal dispersion. The growing polymer chain can react with the double bonds of the triglyceride molecules resulting in grafting. The grafting increases the compatibility between the polymer and the plant oil. However, the polymer molecular weight and the reaction rate decrease when the amount of unsaturated oil increases. A mathematical model was developed taking into account both addition and chain transfer mechanisms to describe the grafting reactions with the plant oils. The model can predict the variation in the polymerization reaction rate depending on the type and concentration of the plant oil in the reaction medium which helps to understand the mechanisms involved and to optimize formulations and operational conditions of polymerizations in the presence of plant oils. Polymerization rate decreases when plants oils are incorporated in PMMA nanoparticles. [ABSTRACT FROM AUTHOR]

Published
2016
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185. Poly(Urea-Urethane) Synthesis by Miniemulsion Polymerization Using Microwaves and Conventional Polymerization.

Author

Valério, Alexsandra, Fortuny, Montserrat, Santos, Alexandre F., Araújo, Pedro H. H., and Sayer, Claudia

Subjects
POLYMERIZATION, URETHANE, MICROWAVES, CHEMICAL reactions, MICROEMULSIONS, FOURIER transform infrared spectroscopy
Abstract

Microwave irradiation has been an interesting alternative for heating systems of several chemical reactions. In this work, a comparative study between microwave reactions and conventional heating is evaluated. The effects of temperature, power, and polyol type on the synthesis of poly(urea-urethane) by step polymerization in miniemulsion are evaluated and the final polymer is analyzed by Fourier transform infrared spectroscopy, gel permeation chromatography, contact angle, and nanoparticles size and size distribution are characterized by dynamic light scattering. Polymerization under microwave irradiation have a higher reaction rate showing advantages of using microwaves in this miniemulsion step polymerization processes. In addition, microwave irradiation also affects particle size, the solubility of the polyurethane, and the urea/urethane ratio. [ABSTRACT FROM AUTHOR]

Published
2015
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188. METABOLISM AND DISPOSITION OF IMATINIB MESYLATE IN HEALTHY VOLUNTEERS

Author

Gschwind, Hans-Peter, primary, Pfaar, Ulrike, additional, Waldmeier, Felix, additional, Zollinger, Markus, additional, Sayer, Claudia, additional, Zbinden, Peter, additional, Hayes, Michael, additional, Pokorny, Rolf, additional, Seiberling, Michael, additional, Ben-Am, Monique, additional, Peng, Bin, additional, and Gross, Gerhard, additional

Published
2005
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198. Synthesis of polybutylene succinate via Lipase-Catalyzed Transesterification: Enzyme Stability, reuse and PBS properties in bulk polycondensations.

Author

Elias Guckert, Fernando, Sayer, Claudia, de Oliveira, Débora, Hermes de Araújo, Pedro H., and Francisco Oechsler, Bruno

Subjects
*ENZYME stability, *POLYCONDENSATION, *MOLAR mass, *TRANSESTERIFICATION, *LIPASES, *POLYBUTENES, *MEDICAL polymers, *KINETIC resolution
Abstract

[Display omitted] • Effect of the enzymatic polycondensation experimental conditions on conversion and molar masses of PBS; • Elucidation of the kinetic behaviour and evolution of molar mass distribution during enzymatic synthesis of PBS; • Reuse of N435 in 6 cycles of PBS catalysis (4 with good enzyme activity); • Attendance of several of the 12 Principles of Green Chemistry; • Subsidies for future works on different polymerization systems catalyzed via N435. Environmental problems involving the inappropriate disposal of non-biodegradable polymers and the production of petrochemical monomers have stimulated the interest in the development of renewable and biodegradable polymers. Among those, polybutylene succinate (PBS) has been highlighted, as it is a biodegradable polyester, synthesized from monomers that can be originated from fermentation processes. Moreover, regarding the application of biocompatible and non-toxic polymers in pharmaceutical and biomedical areas, enzymes can be considered an interesting alternative when compared to metallic catalysts. Therefore, this work aimed to investigate the lipase-catalyzed bulk polycondensation of diethyl succinate and 1,4-butanediol and to evaluate the molar mass distribution of the PBS produced. The recovery of the biocatalyst for application in reuse cycles was also performed. Preliminary tests indicated an enzyme concentration of 10% by mass (regarding the monomers) and a synthesis temperature of 90 °C as the best-operating conditions, in terms of weight of collected by-product (related to the conversion of the functional groups) and the molar masses (M w : 4,000 g.mol−1), in reactions that lasted 90 min. These conditions were used in the subsequent recycling tests of the biocatalyst. The reuse of Novozym 435 allowed for 6 cycles, with good catalytic activity in the first 4 cycles. Moreover, the loss of enzyme activity in the last cycles was recovered through enzyme partial replacement (addition of 25% of fresh enzyme to 75% of used one). The promising results of enzymatic polycondensations performed in bulk aim to contribute to the development of not only more environmentally friendly polymers but also the use of greener reaction conditions. [ABSTRACT FROM AUTHOR]

Published
2022
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