Synthesis and Mechanical Properties of Linear and Long-Chain Branched Homopolymer Topologies via Modular Ligation

点击翻译按钮获取中文摘要

The current extension request builds on the work of the past 3 years funded by the DFG on the topic of "Verarbeitungseigenschaften und Stabilität von RAFT-basierten und modular synthetisierten Polymeren variabler Topologie". Within the requested extension, we wish to exploit our established expertise to achieve two well-defined and clear subsequent aims: (i) Establish the thermomechanical behavior of a new class of modular ligation points that are generated via rapid and efficient photochemical reactions (photo induced click chemistry), yet whose stability under processing conditions has never been assessed. Having access to stability data of such connectivities (here pyrozolines and benzoisoindolediones), which are employed to construct, for example, block copolymers, is of critical importance for their applicability in materials that will undergo processing. In addition, these photochemically generated ligation points are often employed to pattern surfaces and stability information obtained in bulk can be transferred to surfaces, too, on which it is near impossible to obtain directly. (ii) Based on our knowledge obtained in the previous grant regarding the stability and processing conditions we will utilize the different well-defined topologies synthesized in this project as model systems to investigate the mechanical behavior of complex macromolecular architectures with an increasing number of branching points. The rheological characterization will be conducted under oscillatory shear in the linear and non-linear regime (LAOS) and under uniaxial elongation, accompanied by constitutive simulations (MSF and pom-pom) and mimicking of processing conditions using small scale extruders (5 g capacity). To achieve the above aims, we forge a coherent consortium with complementary expertise in precision polymer chemistry (Prof. Barner-Kowollik) for the synthesis of the polymeric materials and expertise in rheological characterization (Prof. Wilhelm).