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

非技术摘要：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成密集的纳米级周期性结构阵列，间距约为10-100 nm。这些材料在一系列纳米技术中很有用，包括制造集成电路和用于过滤或分离的多孔膜。这项提议探索了一种称为Janus多嵌段瓶刷共聚物的嵌段共聚物，其中的分子由主链组成，三种或更多不同聚合物组成的侧链连接在主链上。这些材料自组装成具有不寻常形态的纳米结构，例如层层网状结构，这是普通嵌段共聚物无法形成的，这使得Janus聚合物对纳米制造感兴趣。该提议有两个主要目的：第一，测试关于形成新形态的假设，第二，在聚合物中引入一个含有金属的基团，使其能够形成有用的纳米结构，如微电子金属化导线。成功实现这些目标将有助于解决基于自组装的纳米制造方面的长期需求；特别是金属网和直线型纳米结构的制造。更广泛的影响包括对学生的培训、公共活动和推广活动，以促进科学和工程方面的多样性。技术摘要：这项建议探索了一类Janus多嵌段瓶刷共聚物，这种聚合物微相分离，形成具有分层长度尺度的结构，由上层结构中的子结构组成，如网状层。Janus瓶刷多嵌段共聚物的形态与Janus瓶刷两嵌段共聚物的形态有本质上的不同，将通过实验和计算来研究超结构中分子的限制对亚结构组装的作用。此外，该提案开发了通过聚(N-杂环卡宾)支化大单体路线结合由含金属的N-杂环卡宾(NHC)组成的嵌段的方法，便于在嵌段共聚物中选择性地引入金属物种。采用溶剂退火法和结构分析相结合的方法，研究Janus瓶刷多嵌段共聚物的薄膜形貌和定向自组装，并制备出金属纳米结构，如网状结构。这项拟议的研究将拓宽嵌段共聚物自组装可获得的自组装形态的范围，并通过引入含金属嵌段来扩大瓶刷共聚物的用途。与半导体器件制造相关的形态将成为本项目的一个特别焦点。来自当地社区学院的研究生和本科生，包括暑期研究人员，将接受跨学科领域的培训，有机会与计算合作者互动。结果将被纳入课堂教学和研讨会，并将被组织和存档，供公众查阅。资深研究人员和学生将通过各种项目参与公共宣传和促进多样性。该奖项反映了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。

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.