ERA-Chemistry: Photo-Triggered End-Group Conversion of Synthetic Polymers Prepared via Light-Induced Initiation Pathways

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In the proposed project, an Austrian (Graz University of Technology) and a German group (Karlsruhe Institute of Technology, KIT), with a complementary set of skills, join forces for the in-depth study of photolytically triggered radical transformation pathways of synthetic polymers generated via photoinitiation processes. The aim of the project is to arrive at an encompassing mechanistic understanding of the underpinning reactions that occur when well-defined photolytically generated synthetic polymers are subjected to secondary irradiation processes. Data on such processes is very scarce, yet of paramount importance to (i) judge the propensity of photo-generated polymers to change their end-group characteristics upon post-irradiation or during the primary irradiation process, which can significantly affect their performance and (ii) to exploit UV-triggered end-group transformations for the post-modification of photolytically generated polymers. To obtain the required underpinning mechanistic data, well-defined polymers generated via pulsed laser induced polymerization process will be prepared and subjected to a combination of analytical on-line (in-situ UV-irradiation analysis) and off-line (post UV-irradiation analysis) methodologies, including size exclusion chromatography coupled to mass spectrometry (SEC/ESI-MS), chemically-induced dynamic nuclear polarization (CIDNP) NMR as well as electron paramagnetic resonance (EPR) spectroscopy. The result of the project will be a first-time thorough understanding of the radical end-group transformation pathways for a series of photoinitiator/monomer systems and the establishment of guiding principles that dictate these processes as a function of the photolytically introduced end-groups as well as the type of employed monomer.