Discovery of Self-Assembled Network Phases And Metallic Nanostructures Driven by Confinement

非技术概述：嵌段共聚物是一类含有两个或两个以上不同化学单元的聚合物。因此，这些聚合物可以自发地排列自己，产生密集的纳米级周期性结构阵列，间距约为10-100纳米。这些材料在一系列纳米级技术中都很有用，包括制造集成电路和用于过滤或分离的多孔膜。该提案探索了一种称为Janus多嵌段瓶刷共聚物的嵌段共聚物，其中分子由一个主链组成，其中连接着三种或更多不同聚合物成分的侧链。这些材料自组装成具有不寻常形态的纳米级结构，如网状结构层，这是普通嵌段共聚物无法形成的，这使得Janus聚合物对纳米制造很感兴趣。该提案有两个主要目的：第一，测试关于新形态形成的假设，第二，在聚合物中引入含金属基团，以形成有用的纳米结构，如微电子金属化线。成功实现这些目标将有助于解决基于自组装的纳米制造的长期需求；特别是金属网和直线纳米结构的制造。更广泛的影响包括培训学生、公共活动和推广活动，以促进科学和工程的多样性。技术概述：本提案探讨了一类Janus多嵌段瓶刷共聚物，其微相分离形成具有层次长度尺度的结构，由上层结构（如片层网状结构）中的子结构组成。Janus瓶刷式多嵌段共聚物的形态与Janus瓶刷式双嵌段共聚物的形态在性质上有所不同，上层结构中分子的限制对亚结构组装的作用将通过实验和计算进行研究。此外，该提案开发了通过聚（NHC金属聚合物）支链大单体路线结合含金属n -杂环碳烯（NHC）组成的嵌段的方法，促进了嵌段共聚物中金属物种的选择性引入。采用溶剂退火和结构分析相结合的方法研究了Janus瓶刷型多嵌段共聚物的薄膜形貌和定向自组装，并制备了网状等金属纳米结构。拟议的研究将扩大从嵌段共聚物自组装中获得的自组装形态的范围，并通过引入含金属嵌段来扩展瓶刷共聚物的实用性。与半导体器件制造相关的形态学将成为本项目的重点。来自当地社区学院的研究生和本科生（包括暑期研究员）将在跨学科领域接受培训，并有机会与计算合作者进行互动。结果将纳入课堂教学和研讨会，并将组织和存档，供公众查阅。该奖项反映了美国国家科学基金会的法定使命，并通过基金会的智力价值和更广泛的影响审查标准进行了评估，认为值得支持。

NON-TECHNICAL SUMMARY:Block copolymers are a class of polymers that contain two or more chemically distinct units. As a result, these polymers can spontaneously arrange themselves to produce dense arrays of nanoscale periodic structures with spacings of ~10–100 nm. These materials are useful in a range of nanoscale technologies, including the manufacture of integrated circuits and porous membranes for filtration or separation. This proposal explores a type of block copolymer called a Janus multiblock bottlebrush copolymer, in which the molecules consist of a backbone to which sidechains of three or more different polymer compositions are attached. These materials self-assemble into nanoscale structures with unusual morphologies such as layers of mesh-like structures, which cannot be formed from common block copolymers, making the Janus polymers interesting for nanomanufacturing. The proposal has two major aims: first, testing hypotheses about the formation of novel morphologies, and second, introducing a metal-containing group into the polymer to enable the formation of useful nanostructures such as microelectronic metallization wires. Success in reaching these goals will contribute to solving longstanding needs in nanofabrication based on self-assembly; in particular, the fabrication of metallic meshes and rectilinear nanostructures. Broader impacts include training of students, public events, and outreach activities to promote diversity in science and engineering.TECHNICAL SUMMARY:This proposal explores a class of Janus multiblock bottlebrush copolymers that microphase- separate to form structures with hierarchical length scales consisting of a substructure within a superstructure such as mesh-in-lamella. The morphologies of Janus bottlebrush multiblock copolymers differ qualitatively from those of Janus bottlebrush diblock copolymers and the role of the confinement of the molecules within the superstructure on the substructure assembly will be investigated both experimentally and computationally. Furthermore, the proposal develops methods to incorporate a block consisting of metal-containing N-heterocyclic carbenes (NHC) via a poly(NHC metallopolymer) branched macromonomer route, facilitating the selective introduction of metal species within the block copolymer. Thin film morphologies and directed self-assembly of Janus bottlebrush multiblock copolymers will be investigated using solvent annealing combined with structural analysis, and metal nanostructures such as meshes will be fabricated. The proposed research will broaden the range of self-assembled morphologies obtainable from block copolymer self-assembly, as well as extending the utility of bottlebrush copolymers by introducing a metal-containing block. Morphologies relevant to semiconductor device fabrication will form a particular focus of this project. A graduate student and undergraduates including summer researchers from a local community college will be trained in an interdisciplinary field with the opportunity to interact with a computational collaborator. The results will be incorporated into classroom teaching and seminars and will be organized and archived for public access. The senior researchers and students will engage in public outreach and promotion of diversity through various programs..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.