The Chemical Synthesis, Self-Assembly, and Facial Crosslinking of Dendrimers for the Study of Ultra-Tough Mimics of Spider Dragline Silk

MPS杰出国际博士后研究奖学金（MPS- drf）将用于在德国美因茨的马克斯普朗克聚合物科学研究所（MPIP）进行研究，由Klaus Mullen教授博士和其他合作者指导，这些合作者包括乌尔姆大学的Martin Moller教授博士。迭代设计，合成和表征形态，复合模拟蜘蛛拖丝，一种超韧的拉伸纤维，是这项工作的主题。原型树状大分子的分支单元将被多个化学不混溶的低聚侧链修饰。树状分子的一个侧链相将被交联，并且在树状分子外围的链端长度将被优化，以抑制柱状中间相的大量交联。溶解后，应提供构象受限的树状二聚体。非中心对称的树状构象在二聚化之前需要达到的可达性将使用原子力显微镜与化学修饰的表面进行探测，在溶液中通过与磷脂囊泡的相互作用使用荧光相关光谱进行探测，在体中使用差示扫描量热法进行探测。第二种树突状支架将被合成，具有相似的，化学不混溶的侧链和链端，但在分支单元侧链中具有额外的潜在功能，最初不会进行交联。二聚化后，潜在的功能将被揭示，并用于在最终的复合材料中纳入线性链，以进行大体积交联或物理纠缠。由此产生的复合材料的机械性能有望模仿蜘蛛拖丝的力学性能。虽然这项工作预计不会产生适合商业应用的材料，但它有望评估蜘蛛拖丝的理论机制，负责其卓越的机械韧性。希望这些结论将对先进复合材料的未来产生影响，并对开发更实用的材料具有不可估量的价值。

An MPS Distinguished International Postdoctoral Research Fellowship (MPS-DRF) will be used to perform research at the Max Planck Institute for Polymer Science (MPIP) in Mainz, Germany with the guidance of Prof. Dr. Klaus Mullen and additional collaborators for specialized techniques that are not available the MPIP, including Prof. Dr. Martin Moller at the University of Ulm. The iterative design, synthesis, and characterization of a morphological, composite mimic of spider dragline silk, an ultra-tough tensile fiber, is the subject of this work. The branching units of prototypical dendrimers will be modified with multiple, chemically-immiscible oligomeric side chains. One side chain phase of the dendrimer will be crosslinked, and length of the chain ends at the periphery of the dendrimer will be optimized in order to suppress bulk crosslinking in a columnar mesophase. Upon dissolution, conformationally-restricted, dendrimeric dimers should be afforded. The accessibility that the non-centrosymmetric, dendrimer conformation needs to reach before dimerization will be probed using atomic force microscopy with chemically-modified surfaces, in solution through the interaction with phospholipid vesicles using fluorescence correlation spectroscopy, and in the bulk using differential scanning calorimetry. A second dendrimer scaffold will be synthesized bearing similar, chemically-immiscible side chains and chain ends, but with an additional, latent functionality in the branching unit side chain which will not initially undergo crosslinking. After dimerization, the latent functionality will be unmasked and used to incorporate linear chains for bulk crosslinking or physical entanglement in a final composite. The mechanical properties of the resulting composite are expected to mimic those of spider dragline silk.While this work is not expected to produce materials amenable to commercial application, it is expected to assess the theoretical mechanism of spider dragline silk responsible for its remarkable mechanical toughness. It is the hope that such conclusions will be drawn about the future of advanced composite materials and that they will be invaluable to the development of more practical materials.