Vertically Oriented Anisotropic Nanoparticles in Polymer Matrices

非技术性概述：为了促进聚合物科学的进步，本项目的重点是聚合物纳米复合材料。 由于它们是如此多的应用的基础，聚合物纳米复合材料的研究影响和改进了从复杂设备（如能源生产太阳能电池）到日常材料（如更轻的包装）的技术。该项目试图解决的基本问题是那些管理各向异性颗粒在嵌段共聚物中的组装。具体来说，该项目将产生垂直取向的各向异性颗粒，具有受控的规则分离，这样做将促进对具有特殊几何形状的聚合物材料中的纳米棒和纳米片的理解，例如基质中的纳米柱或交替的纳米片。由此产生的关于如何自组装垂直取向的纳米粒子的见解将使科学界能够探索各种各向异性特性，包括分子，电和热传输。拟议研究的成功结果将是精确控制聚合物纳米复合材料薄膜中纳米棒和纳米片的垂直方向和横向间距，这对纳滤，传感，阻隔涂层和照明领域的社会具有潜在的好处。除了培养受过良好教育、掌握科学技能的劳动力外，研究和教育的结合还在多个层面上造福社会。除了研究生教育，来自美国和国外的本科生以及费城当地高中的参与者将受益于研究和指导。为了吸引广泛的受众，研究人员将每年参加Nanoday@Penn和Philly Materials Day，分别吸引200多名高中生和2000多名与会者。此外，每年的教师材料科学研讨会将继续以及与中央高中，费城，这暴露了大量的少数民族学生人口的机会在STEM领域的独特的伙伴关系。技术摘要：控制纳米棒和纳米片的嵌段共聚物（BCP）薄膜的垂直排列的热力学和动力学原理将进行调查。各向异性颗粒将接枝聚合物刷，以控制它们与其他颗粒和BCP的相互作用。研究目标是：（1）在嵌段共聚物的垂直圆柱形区域中垂直排列纳米棒。金属，纳米荧光粉和半导体纳米棒将在聚（苯乙烯-b-2-乙烯基吡啶）（PS-b-P2 VP）和P2 VP膜进行研究。纳米棒直径和长度对垂直取向的影响特别令人感兴趣，以及使用纳米棒的二元混合物将它们引导到特定的微区。(2)在嵌段共聚物的垂直片层域中垂直排列纳米片。氧化石墨烯，纳米荧光粉和锂皂石纳米片将在聚（苯乙烯-b-甲基丙烯酸甲酯）（PS-b-PMMA）和PS膜进行研究。(3)研究溶剂退火过程中均聚物和嵌段共聚物薄膜中纳米棒组装的动力学。单粒子跟踪将用于测量纳米棒的流动性。修改后的场论模拟，包括动力学将指导实验，并提供热力学和动力学之间的平衡，区分最终morphology.The研究利用新的和持续的合作，以创建新的粒子聚合物组件，进行原位表征，垂直排列的聚合物纳米复合材料的模型。具体而言，分散将作为一个功能的颗粒形状，尺寸和表面化学，膜厚度和界面相互作用，和BCP的组成和大小进行研究。三维场论模拟将指导实验参数的选择，并提供一个热力学框架，了解粒子和BCP取向之间的相互作用。BCP形态将通过TEM、AFM和SAXS确定，颗粒位置通过TEM、FIB-SEM确定，深度分布通过RBS确定。GISAXS将用于跟踪溶剂退火过程中的原位结构演变。光学性质将通过紫外-可见光谱表征。这项研究得益于与桑迪亚国家实验室和先进光源的无资金合作。

NON-TECHNICAL SUMMARY:To promote the progress of polymer science, this project is focused on polymer nanocomposites. Because they underlie so many applications, polymer-nanocomposite research impacts and improves technologies ranging from complex devices, such as energy producing solar cells, to everyday materials, such as lighter packaging. The fundamental issues that the project seeks to address are those that govern the assembly of anisotropic particles in block copolymers. Specifically, the project will produce vertically-oriented, anisotropic particles with controlled regular separations, and in so doing will advance understanding of nanorods and nanoplates in polymeric materials having special geometries such as nanocylinders in a matrix or alternating nanosheets. The resulting insights about how to self-assemble vertically oriented nanoparticles will enable the scientific community to explore a variety of anisotropic properties including molecular, electrical, and thermal transport. A successful outcome of the proposed research will be precise control over the vertical orientation and lateral spacing of nanorods and nanoplates in polymer nanocomposite films, which have potential benefits to society in areas of nanofiltration, sensing, barrier coatings and lighting. Besides producing a well educated, scientifically skilled work force, the integration of research and education benefits society at several levels. Besides graduate education, undergraduates from the US and abroad as well as local Philadelphia high school participants will benefit from research and mentoring. To reach a broad audience, researchers will participate annually in Nanoday@Penn and Philly Materials Day, which attract over 200 high school students and 2000 attendees, respectively. Furthermore, the annual Teachers Materials Science Workshop will continue as well as a unique partnership with Central High School, Philadelphia, which exposes a large minority student population to opportunities in STEM fields.TECHNICAL SUMMARY:The thermodynamic and dynamic principles that control vertical alignment of nanorods and nanoplates in block copolymer (BCP) films will be investigated. Anisotropic particles will be grafted with polymer brushes to control their interactions with other particles and BCP. Research objectives are to: (1) Vertically align nanorods in perpendicular cylindrical domains of block copolymers. Metallic, nanophosphor and semiconducting nanorods will be investigated in poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP) and P2VP films. The effect of nanorod diameter and length on vertical orientation is of particular interest, as well as using binary mixtures of nanorods to direct them to specific microdomains. (2) Vertically align nanoplates in perpendicular lamella domains of block copolymers. Graphene oxide, nanophosphor and laponite nanoplates will be investigated in poly(styrene-b-methyl methacrylate) (PS-b-PMMA) and PS films. (3) Investigate the dynamics of nanorod assembly in homopolymer and block copolymer films during solvent annealing. Single particle tracking will be used to measure nanorod mobility. Field theoretic simulations modified to include dynamics will guide experiments and provide insight into the balance between thermodynamics and dynamics that differentiates the final morphology.The research leverages new and continuing collaborations to create novel particle-polymer assemblies, perform in situ characterization, and model vertically aligned polymer nanocomposites. Specifically, dispersion will be studied as a function of particle shape, size and surface chemistry, film thickness and interface interactions, and BCP composition and size. Three-dimensional field theoretic simulations will guide the choice of experimental parameters and provide a thermodynamic framework for understanding the interplay between particle and BCP orientation. BCP morphology will be determined by TEM, AFM and SAXS, particle location by TEM, FIB-SEM and depth profiling by RBS. GISAXS will be used to follow in situ structural evolution during solvent annealing. Optical properties will be characterized by UV-vis spectroscopy. This research benefits from unfunded collaborations with Sandia National Laboratories and the Advanced Light Source.