Guiding Polymer Assembly with Molecular Architecture

非技术人员合成化学家长期以来一直努力模仿大自然构建大型复杂聚集体和分子机械的能力，这些聚集体和分子机械通过蛋白质等定义明确的小构件的自发结合在体内执行关键功能。受生物类比的启发，本研究项目旨在开发一类具有刷状结构的新型全合成聚合物分子，该分子可以三维控制分子的形状及其相互作用，以指导仿生分子的组织。这种高度可调的分子构件将通过新开发的合成化学方法来制备，并通过各种技术进行研究，以形成先进的材料。这些材料将用于水过滤膜、均匀的仿生泡囊和轻质纳米复合材料，用于各种能源和健康相关应用。计划中的研究活动将推进目前对分子组装的理解，允许前所未有的仿生水平，并为制造高价值纳米材料提供潜在的新途径。拟议研究计划的科学方面将与更广泛的推广和教育举措相结合，旨在通过教师专业发展和研究生和本科生培训，改善科学/技术/工程/数学(STEM)教育，并培养一支具有竞争力的STEM劳动力队伍。技术总结该项目下进行的研究旨在开发由分子结构指导的聚合物组装的新模式。通过引入三个新的结构基元，将开发出对组成轮廓和分子间相互作用具有持久形状和空间控制的梳状大分子：沿主干具有梯度组成锥形的瓶刷结构，瓶刷外围的四重氢键功能，以及高度缔合的聚酰亚胺刷子。由瓶刷结构在空间上引导的不同分子间相互作用的组合将被用于驱动聚合物构建块组装成高度有序的纳米材料。将追求三个具体目标：(1)梯度瓶刷共聚物的合成和熔体自组装；(2)具有战略定向氢键相互作用的两亲性瓶刷共聚物的程序化仿生组装成高度均匀的多孔聚集体；(3)通过控制核壳瓶刷共聚物的各向异性聚集来合成聚酰亚胺纳米颗粒和纳米纤维。这一研究计划的成功成果将提供一种新的分子结构，控制自组装纳米结构中分子间相互作用和分子取向的方向性的设计原则，以及具有广泛性能和应用的以前无法获得的材料的潜在制造。

NON-TECHNICAL SUMMARYSynthetic chemists have long striven to mimic nature's ability to construct large and complex aggregates and molecular machinery that perform critical functions in the body by spontaneous association of small, well-defined building blocks such as proteins. Inspired by this biological analogy, this research project aims to develop a new class of fully synthetic polymer molecules with brush-like architecture that provides three-dimensional control over the shape of the molecules and their interactions to guide the biomimetic molecular organization. Such highly tunable molecular building blocks will be prepared by newly developed synthetic chemistry methods and studied by a variety of techniques for the formation of advanced materials. These materials will be relevant to water filtration membranes, uniform biomimetic vesicles, and lightweight nanocomposites, for a variety of energy and health related applications. The planned research activities will advance the current understanding of molecular assembly, allow for unprecedented levels of biomimicry, and offer potentially new avenues for the fabrication of high-value nanomaterials. The scientific aspects of the proposed research program will be integrated with broader outreach and educational initiatives aimed at improving science/technology/engineering/mathematics (STEM) education and developing a competitive STEM workforce through teacher professional development and graduate and undergraduate student training.TECHNICAL SUMMARYThe research to be conducted under this project aims to develop new modes of polymer assembly directed by molecular architecture. Comb-like macromolecules with a persistent shape and spatial control over compositional profile and intermolecular interactions will be developed by introducing three new structural motifs: bottlebrush architecture with a gradient compositional taper along the backbone, quadruple hydrogen bonding functionalities on bottlebrush periphery, and highly associating polyimide brushes. A combination of different intermolecular interactions spatially guided by the bottlebrush architecture will be used to drive the assembly of polymeric building blocks into highly ordered nanomaterials. Three specific objectives will be pursued: (1) synthesis and melt self-assembly of gradient bottlebrush copolymers, (2) programmed biomimetic assembly of amphiphilic bottlebrush copolymers with strategically directed hydrogen bonding interactions into highly uniform porous aggregates, and (3) synthesis of polyimide nanoparticles and nanofibers by controlled anisotropic aggregation of core-shell bottlebrush copolymers. The successful outcome of this research program will provide access to a new molecular architecture, design principles to control the directionality of intermolecular interactions and molecular orientation within the self-assembled nanostructures, and the potential fabrication of previously unattainable materials with a wide range of properties and applications.