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

在拟议的项目中，奥地利（格拉茨理工大学）和德国（卡尔斯鲁厄理工学院，KIT）拥有互补的技能，联手深入研究通过光引发过程产生的合成聚合物的光解引发自由基转化途径。该项目的目的是对定义明确的光解生成的合成聚合物受到二次辐照过程时发生的基础反应有一个全面的机制理解。这类过程的数据非常少，但对于(i)判断光生成聚合物在辐照后或初次辐照过程中改变其端基特征的倾向至关重要，这可以显著影响它们的性能；（ii）利用紫外线触发的端基转化对光解生成的聚合物进行后改性。为了获得所需的基础机理数据，将制备通过脉冲激光诱导聚合过程生成的定义明确的聚合物，并将其结合在线（原位紫外线照射分析）和离线（紫外线照射后分析）分析方法，包括尺寸排除色谱-质谱（SEC/ESI-MS），化学诱导动态核极化（CIDNP）核磁共振以及电子顺磁共振（EPR）波谱。该项目的结果将是第一次彻底了解一系列光引发剂/单体系统的自由基端基转化途径，并建立指导原则，指导这些过程作为光解引入的端基的功能以及所使用的单体类型。

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.