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dc.contributor.advisor Buback, Michael Prof. Dr. de
dc.contributor.author Barth, Johannes de
dc.date.accessioned 2011-11-22T15:09:27Z de
dc.date.accessioned 2013-01-18T10:31:47Z de
dc.date.available 2013-01-30T23:51:22Z de
dc.date.issued 2011-11-22 de
dc.identifier.uri http://hdl.handle.net/11858/00-1735-0000-0006-B075-2 de
dc.description.abstract Die vorliegende Arbeit stellt eine zeitaufgelöste Pulslaserpolymerisations- Elektronenspinresonanz-Methode vor mit der die Kinetik von komplizierten radikalischen Polymerisationen mit mehreren Typen von auftretenden Radikalen untersucht werden kann. de
dc.format.mimetype application/pdf de
dc.language.iso eng de
dc.rights.uri http://creativecommons.org/licenses/by-nc-nd/3.0/ de
dc.title Radical Polymerization Kinetics in Systems with Transfer Reactions Studied by Pulsed-Laser-Polymerization and Online EPR-Detection de
dc.type doctoralThesis de
dc.title.translated Studien zur Kinetik radikalischer Polymerisationen mit zwei Sorten von Radikalspezies durch Pulslaser Polymerisation mit Online EPR-Spektroskopie de
dc.contributor.referee Buback, Michael Prof. Dr. de
dc.date.examination 2011-10-25 de
dc.subject.dnb 540 Chemie de
dc.description.abstracteng The SP-PLP-EPR technique has been developed for very detailed kinetic investigations into radical polymerization. The method which combines single-pulse-pulsed-laser-polymerization (SP-PLP) with electron paramagnetic resonance spectroscopy (EPR) allows for direct online monitoring of radical concentration with a time-resolution of ìs after applying an intense laser SP. Polymerizations have been carried out at ambient pressure within a broad temperature range in bulk and in solutions, including water and ionic liquids as solvents. SP-PLP-EPR provides access to the highly complex diffusion-controlled termination kinetics of radicals as a function of chain-length during polymerization. A unique feature of the method is that different types of radicals may be followed independently. Kinetic fitting of measured concentration vs. time traces via PREDICI® simulation yields reliable rate coefficients. Monitoring of midchain radicals formed via backbiting of chain-end radicals in acrylic acid and acrylate polymerizations allows for studying intramolecular transfer and individual termination steps of both species. Tracing of propagating and of intermediate radicals during reversible addition fragmentation transfer (RAFT) polymerization provides access to RAFT addition, fragmentation and to termination reactions. By directly measuring the lifetime of the intermediate radical during dithiobenzoate-mediated acrylate polymerization, a reliable fragementation rate coefficient has been determined which value excludes the so-called slow-fragementation from explaining rate retardation. SP-PLP-EPR in the presence of copper(II)-complexes is suitable for measuring deactivation rate coefficients during atom transfer radical polymerization (ATRP).A physically based description of chain-length-dependent termination has been developed via SP-PLP-EPR experiments on methacrylate and acrylate monomers. The termination rate coefficient of macroradicals of identical degree of polymerization is adequately represented via a composite model. The decay of termination rate coefficient with increasing chain length is described by power-laws with higher and lower (negative) exponent values for chain-lengths below and above a crossover chain-length of about 50 monomer units. Termination in both regimes proceeds against the friction of monomer and solvent. Hence the absolute value and the temperature dependence of the termination reaction are determined by the fluidity of the monomer-solvent mixtures. Rate coefficients for transfer of chain-end radicals to form midchain radicals (backbiting) and for monomer addition to midchain radicals have been measured for aqueous-phase polymerization of non-ionized and fully ionized acrylic acid. These data are important for modeling of industrially relevant polymerization processes. de
dc.contributor.coReferee Vana, Philipp Prof. Dr. de
dc.subject.topic Chemistry de
dc.subject.ger Polymerisation de
dc.subject.ger Kinetik de
dc.subject.ger Kettenlängenabhängig de
dc.subject.ger Transfer de
dc.subject.ger Backbiting de
dc.subject.ger Terminierung de
dc.subject.ger Propagation de
dc.subject.ger ESR / EPR -Spektroskopie de
dc.subject.ger Acrylsäure de
dc.subject.ger Butylacrylat de
dc.subject.ger Methylmethacrylat de
dc.subject.ger Ionische Flüssigkeiten de
dc.subject.ger Laser de
dc.subject.eng Polymerization de
dc.subject.eng Kinetic de
dc.subject.eng chain-length dependent de
dc.subject.eng transfer de
dc.subject.eng backbiting de
dc.subject.eng termination de
dc.subject.eng propagation de
dc.subject.eng ESR / EPR -spectroscopy de
dc.subject.eng acrylic acid de
dc.subject.eng butyl acrylate de
dc.subject.eng polymer de
dc.subject.eng ionic liquid de
dc.subject.eng Laser de
dc.subject.bk 35.13 de
dc.identifier.urn urn:nbn:de:gbv:7-webdoc-3255-6 de
dc.identifier.purl webdoc-3255 de
dc.affiliation.institute Fakultät für Chemie de
dc.subject.gokfull SG de
dc.identifier.ppn 684933446 de

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