Boston New Media Library

The Boston New Media Library mixes new media elements with those of a traditional library

Synthese funktionalisierter Phenolpolymere durch HRP-katalysierte Polyrekombination

ZUSAMMENFASSUNG: Die durch das Enzym Horseradish Peroxidase katalysierte oxidative Polymerisation substituierter Phenole gewährt einen bequemen Zugang zu funktionalisierten Phenolpolymeren, deren Anwendung als Ersatz für konventionelle Phenol-Formaldehyd-Harze zur Zeit intensiv erforscht wird. Zur Zeit werden Polymerisation dieser Art in Mischungen aus organischen Lösungsmitteln (z.B. 1,4-Dioxan) und Puffer durchgeführt. Im Rahmen dieser Arbeit wurde eine HRP-katalysierte Phenolpolymerisation von wasserunlöslichen Methacryloyl- und Maleinimid-substituierten Phenolen in 100% Pufferlösung durch die Verwendung von 2,6-methylierten Cyclodextrinen als carrier erreicht. Die so hergestellten Oligomere wurden mit Styrol und MMA copolymerisiert. Weitere Untersuchungen hatten die Synthese photoreaktiver Phenolpolymere mit Zimtsäure- oder Nitrongruppen in der Seitenkette, die Synthese thermisch vernetzbarer Phenolcopolymere aus Furan-2-carboxylsäure-(4-hydroxy-phenyl)-amid und N-methacryloyl-11-aminoundecanoyl-4-hydroxyanilid sowie die Synthese eines Redoxpolymeren ausgehend von 4-Aminophenol zum Ziel. Daneben wurden Strategien zur enzymatisch katalysierten Synthese von Poly[para-phenylenen], hyperverzweigten Phenolpolymeren und biologisch aktiven Phenolpolymeren entwickelt, und detaillierte Untersuchungen zum Polymerisationsmechanismus und zur Struktur der entstehenden Phenolpolymere vorgestellt. Die vorgestellten Phenolpolymere bestehen hoechstwahrscheinlich aus polyaromatischen Helices, da diese p-substituierten Phenole während des Rekombinationsprozesses bevorzugt an den ortho- Positionen rekombinieren.ABSTRACT: The present work deals with the enzyme horseradish peroxidase (HRP), which has been used extensively by several research groups for the oxidative polymerization of a wide variety of substituted phenols and anilines. This enzyme-catalyzed process is expected to be an alternative route for the preparation of phenolic polymers without the use of toxic formaldehyde, used as a coupling comonomer for the production of conventional phenolic resins. Enzyme-catalyzed reactions of this type are usually carried out in mixtures of an organic solvent (e.g. 1,4-dioxane) and buffer. During this present work, the enzymatic polymerization of methacryloyl- and maleimide-substituted phenols in 100% buffer was realized by using 2,6-methylated cyclodextrin as carrier for the otherwise water-insoluble phenols. The resulting oligomers were copolymerized with Styrene and MMA. Further research dealt with the synthesis of photo-reactive polyphenols with cinnamoyl- or nitron-groups in the side-chain, the study of the copolymerization behavior of N-(4-hydroxyphenyl)-2-furamide and N-methacryloyl-11-aminoundecanoyl-4-hydroxyanilide and the formation of a redox polymer prepared by protected 4-amino-phenol. Approaches to the enzymatic synthesis of poly[para-phenylenes], hyperbranched phenol polymers, and biological active phenol polymers were presented and detailed analysis of the polymerization behavior and the structure of the resulting polymers were performed. The presented phenol polymers probably consist of polyaromatic helices, since the recombination occurs mainly at the ortho-positions of the presented p-substituted phenols

Boston New Media Library

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Investigation of de Vries SmA* mesophases in low molecular weight organosiloxane compounds

A series of novel low molecular weight organosiloxane compounds have been investigated using a number of techniques such as: texture, birefringence measurements and dielectric spectroscopy. Some materials under investigation are shown to have a direct transition to de Vries SmA* phase on cooling from the isotropic phase, whereas the others show first a transition from isotropic to orthogonal SmA*, followed by a transition from orthogonal SmA* to de Vries SmA* phase. We propose a phase diagram for a possible phase transition from SmA* to SmC* phase

Enzyme Initiated Radical Polymerizations

Biocatalysis is propagating into practically every area of organic chemistry, amongst them radical polymerizations. A review of the recent developments of this dynamic and quickly evolving area of research is presented together with a critical evaluation of its potential to yield novel polymers and/or environmentally more benign synthetic procedures OA-fund TU DelftBiotechnologyApplied Science