Role of Monomer Sequence and Polymer Topology in Polymer Assembly

第1部分：非技术性的SUMMARYA由于分子很长，聚合物链可以呈现从完全伸展到折叠的多种形状。虽然一些天然聚合物的形状，即蛋白质，已经进化成非常复杂的形状，并嵌入了重要的功能，但合成聚合物的链形状相对粗糙。因此，改进对链形状的控制可以促进材料的设计，适用于有机电子、结构塑料和复杂流体等各种应用。最近，合成方法已经得到改进，我们可以制造出像蛋白质一样复杂的化学聚合物链，但设计出具有特定形状的材料的能力仍然遥不可及。从蛋白质中获得灵感，PI的团队将利用聚合物化学的这些发展来确定控制这些聚合物的链形状和组装的设计规则。此外，将聚合物的分子设计与其三维形状联系起来的见解将提高我们对自然蛋白质折叠的理解，并开发必要的工具来合成具有生物学固有复杂性和功能的材料。该项目的一个重要组成部分侧重于扩大在所有层面上对聚合物科学的参与，包括：(1)吸引即将到来的社区大学转学学生参与研究工作，(2)“科学之夜”推广活动的强有力的计划，以及(3)本科生和研究生研究人员的培训。第2部分：技术单体序列和聚合物拓扑是控制聚合物构象和自组装的两个基本设计手柄。最近在序列控制多肽的克级合成方面的进展使直接测试单体序列和聚合物拓扑如何控制链崩溃和利用先前未实现的介观结构的预测成为可能。该项目跨越了化学图案化和聚合物拓扑学，作为微调材料性能的手柄，从而为设计定制软材料和合成生物系统奠定了基础。除了精确定义的单体序列、连接位置和臂长度外，多肽还提供用户定义的链刚性，提供另一个手柄来控制链形状和界面曲率。PI的团队将使用这个平台来探索如何使用序列和动态分子内相互作用来调整折叠的分子结构，为蛋白质折叠和胶体设计提供见解。此外，他们还将合成具有非线性拓扑结构的多肽，并研究其熔体自组装，从而消除大多数合成路线固有的分散效应。特别是，该项目将确定界面曲率对所产生的形态的作用，并探索如何将构象不对称和复杂的拓扑(嫁接和星形结构)相结合来微调自组装。此外，PI的团队将模拟多肽作为受控平台，从解决两个悬而未决的问题的系统开始，为嫁接聚合物设计产生见解：(1)嫁接/明星/瓶刷之间的界限在哪里？以及(2)不同瓶刷中的主干取向之间的内在竞争能否被用来获得新的形态？这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

PART 1: NON-TECHNICAL SUMMARYAs very long molecules, polymer chains can take on many shapes ranging from fully extended to collapsed. While the shape of some natural polymers, namely proteins, has evolved to be very complex and embeds significant functionality, synthetic polymer chain shapes are comparatively crude. Improved control of chain shape could, therefore, advance the design of materials for applications as diverse as organic electronics, structural plastics, and complex fluids. Recently, synthetic methods have improved to the point where we can make polymer chains with chemistry as complex as proteins, but the ability to design materials that attain specific shape remains out of reach. Taking inspiration from proteins, the PI's group will leverage these developments in polymer chemistry to determine the design rules controlling the chain shape and assembly of these polymers. Further, insights connecting the molecular design of a polymer to its three-dimensional shape will improve our understanding of natural protein folding and develop the tools necessary to synthesize materials with the complexity and function inherent in biology. An important component of the project focuses on broadening participation in polymer science at all levels including: (1) Engaging incoming community-college transfer students in research efforts, (2) A robust program of “Science Night” outreach activities, and (3) The training of undergraduate and graduate student researchers.PART 2: TECHNICAL SUMMARYMonomer sequence and polymer topology are two essential design handles to control polymer conformation and self-assembly. Recent advances in the gram-scale synthesis of sequence-controlled polypeptoids now make it possible to directly test predictions of how monomer sequence and polymer topology control chain collapse and leverage access to previously unrealized mesostructures. This project spans both chemical patterning and polymer topology as handles for fine-tuning material properties and, thus, builds a foundation for designing made-to-order soft materials and synthetic biological systems. Beyond precisely defined monomer sequence, junction location, and arm length, polypeptoids also provide user-defined chain stiffness, offering yet another handle to control chain shape and interfacial curvature. The PI's group will use this platform to explore how sequence and dynamic intramolecular interactions can be used to tune collapsed molecular structure, providing insight on protein folding and colloid design. In addition, they will synthesize polypeptoids with non-linear topologies and study their melt self-assembly, thus eliminating the dispersity effects intrinsic to most synthetic routes. In particular, the project will determine the role of interfacial curvature on resulting morphologies and explore how conformational asymmetry and complex topologies (graft and star architectures) can be combined to fine-tune self-assembly. Further, the PI's group will model polypeptoids as controlled platforms to generate insights for graft polymer design, beginning with systems to address two outstanding questions: (1) where does the limit between graft/star/bottlebrush lie? and (2) can the inherent competition between backbone orientation in inhomogeneous bottlebrushes be used to access new morphologies?.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.