CAREER: Complex Hierarchical Self-Assembly Templated by Block Copolymers: Phase Structures, Nano Fabrication and Nano-Electrooptic Properties

分级自组装是纳米技术的重要组成部分，它提供了制造纳米结构集合的为数不多的实用策略之一。分层结构中的结构复杂性特别重要，因为它提供了在单一材料中组合不同功能的实用手段。这一职业发展计划的目标是通过结合二维(2-D)液晶(LC)有序化和嵌段共聚物微相分离过程来实现复杂的分级自组装结构。(1)设计、合成和系统研究了一系列弯核液晶(BCLC)两嵌段共聚物，以获得新型复杂的层状结构，包括嵌段共聚物片层中的LC柱状相(Col-in-Lam)、柱状中的Col(Col-in-Cyl)和球中的Col(Col-in-Sph)结构等。(2)制备定义良好的纳米构建块(如纳米多孔板、棒、球等)。使用这些分层自组装的两嵌段共聚物作为模板。(3)探索这些新型层状结构的纳米电光性质。在所提出的两嵌段共聚物体系中，将实现独特的片层厚度可控的铁电反铁电性。电场可调纳米结构也将被研究。这项拟议的研究将首次将二维液晶有序化纳入嵌段共聚物微相分离产生的有序纳米空间中。所得到的分级结构在1-5 nm和10-100 nm长度尺度上都具有复杂的性质。从科学的角度来看，该系统提供了一个独特的机会来探索复杂的相结构、小的相尺寸和大的界面效应对LC以及嵌段共聚物相行为的影响。在这些较小的环境中，LC相的稳定性可能会发生改变，并可能产生新的相结构。从技术角度来看，这种分层结构可以用作纳米制造应用的模板。不同长度尺度上的良好关联结构也可能为将纳米尺度上的新性质转移到更高长度尺度上提供解决方案。此外，由于其特殊的结构复杂性，这些层次结构可以作为进一步的纳米科学和纳米技术研究的支架，特别是对于纳米器件的制造。结构的复杂性和层级也可能是设计能够模仿优雅的生活系统的合成材料的关键。拟议职业发展计划的教育部分包括：(1)通过开设题为“聚合物和纳米技术”的新课程，解决聚合物纳米科学和纳米技术现代发展的教育需要。(2)让高中生和教师，特别是代表性不足的人群，参与拟议的聚合物纳米技术研究活动。(3)通过Drexel的Co-op系统，发展PI实验室与行业之间的长期合作。这些拟议的教育活动产生了更广泛的影响。首先，拟议的计划将通过一系列导师计划，让高中生和教师参与研究活动，从而帮助弥合教育发展水平之间的现有差距。其次，由于费城地区代表不足群体的人口很多，拟议的外展方案将专门针对鼓励代表不足群体的参与。第三，建议的研究成果将通过科学期刊上的出版物、与工业界合作开发的产品以及更多训练有素的中等教育教师作为参与研究活动所获得的知识的自然结果而广泛传播。最后，通过与费城周边地区的国家实验室和学区建立合作关系，拟议的计划将极大地加强研究和教育的基础设施。结合德雷克塞尔大学提供的“启动一揽子计划”，拟议的计划还将使PI能够建立一个最先进的聚合物表征中心，这将使德雷克塞尔大学和附近的行业受益。

Hierarchical self-assembly is an essential part of nanotechnology and it offers one of the few practical strategies for making ensembles of nanostructures. Structure complexity in the hierarchical structures is of particular importance since it provides a practical means to combine different functionalities within a single material. The aim of this CAREER development plan is to achieve complex hierarchical self-assembled structures via combining two-dimensional (2-D) liquid crystalline (LC) ordering and block copolymer microphase separation process. The proposed research activities include: (1) Design, synthesize, and systematically investigate a series of bent-core liquid crystalline (BCLC) diblock copolymers in order to achieve novel complex hierarchical structures including LC columnar phase (Col) in block copolymer lamella (Col-in-Lam), Col in cylinder (Col-in-Cyl) and Col in sphere (Col-in-Sph) structures, etc. (2) Fabricate well-defined nano building blocks (such as nano porous plates, rods, spheres, etc.) using these hierarchically self-assembled diblock copolymers as templates. (3) Explore the nano-electrooptic properties of these novel hierarchical structures. Unique lamellar thickness controlled ferro-antiferroelectric properties will be realized in the proposed diblock copolymer system. Electric field tunable nanostructures will also be investigated. The proposed research will, for the first time, incorporate 2-D LC ordering into the ordered nanospace created by block copolymer microphase separation. The resulting hierarchical structures possess complex natures at both 1-5 nm and 10-100 nm length scales. From a scientific point of view, this system provides a unique opportunity to explore the complex phase geometry, small phase size and large interface effects on LC as well as block copolymer phase behaviors. LC phase stability might be altered in these small environments and novel phase structures might be generated. From the technological point of view, the hierarchical structures could be used as templates for nano fabrication applications. Well-correlated structures at different length scales might also provide a solution for the transfer of the novel properties at the nanoscale into a higher length scale. Furthermore, these hierarchical structures can serve as a scaffold for further nanoscience and nanotechnology research, particularly for nano device manufacturing due to their specific structure complexity. The structural complexity and hierarchies might also hold the key to designing synthetic materials that can mimic the elegant living systems. The educational component of the proposed CAREER development plan includes (1) Address the needs for the education of modern developments in polymer nanoscience and nanotechnology by developing a new course entitled Polymers and Nanotechnology. (2) Involve high school students and teachers, particularly under-represented populations, in the proposed polymer nanotechnology research activities. (3) Develop long-term collaborations between the PI's laboratory and industry through Drexel's Co-op system. These proposed education activities impose a broader impact. First, the proposed plan will help to bridge the existing gap between levels of educational developments by involving high school students and teachers in research activities through a number of mentorship programs. Secondly, due to the high population of under-represented groups in the Philadelphia region, the proposed out-reach program will be specifically geared towards encouraging the participation of under-represented populations. Thirdly, the proposed research results will be widely disseminated through publications in scientific journals, product development resulting from collaborations with industry and, as a natural outgrowth of gained knowledge resulting from involvement in research activities, more highly trained secondary education teachers. Lastly, through the establishment of collaborations with national laboratories and school districts in the surrounding Philadelphia region, the proposed plan will dramatically enhance the infrastructure for research and education. Combined with the "start-up package" supplied by Drexel University, the proposed plan will also enable the PI to establish a state-of-the-art polymer characterization center that will benefit both Drexel University and nearby industry.