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Max Planck聚合物科学研究所（MPIP）进行研究，并由Klaus马伦教授和其他合作者（包括乌尔姆大学的Martin Moller教授和博士）指导MPIP无法提供的专业技术。 迭代设计，合成和表征的形态，复合材料模仿蜘蛛拖丝，超韧性拉伸纤维，是这项工作的主题。 原型树枝状聚合物的分支单元将用多个化学不混溶的低聚侧链修饰。 树枝状聚合物的一个侧链相将被交联，并且树枝状聚合物外围的链端的长度将被优化以抑制柱状中间相中的本体交联。 在溶解时，应提供构象受限的树枝状二聚体。 非中心对称的，树枝状大分子构象需要达到二聚化之前的可及性将使用原子力显微镜与化学改性的表面，在溶液中通过与磷脂囊泡的相互作用，使用荧光相关光谱，并在散装使用差示扫描量热法进行探测。 将合成第二树枝状聚合物支架，其带有类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官能团，其最初不会经历交联。 在二聚化之后，潜在的官能度将被揭开并用于在最终复合物中引入线性链以用于本体交联或物理缠结。 所得到的复合材料的机械性能，预计模仿那些蜘蛛拖丝。虽然这项工作预计不会产生适合商业应用的材料，预计将评估蜘蛛拖丝的理论机制，负责其显着的机械韧性。 我们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宝贵的价值。

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.