UNS: Interfacial Behavior and Thermodynamics of Block Copolymer Directed Self-Assembly

1512517-Henderson一种特殊形式的聚合物，可以定制成具有非常独特的性能，通常被称为嵌段共聚物。嵌段共聚物是通过简单地将两种不同类型的聚合物链连接在一起而制成的。由于不同类型的聚合物不喜欢混合，就像油和水分离一样，这两个不同的聚合物链或块也试图彼此分离，但由于它们粘合在一起，只能在与聚合物分子的长度规模相当的距离内移动。这自然产生了具有纳米尺度结构和有序性的材料。由于这种微米和纳米结构，这些相分离和有序的嵌段共聚物可以具有非常独特的性质。这种有序嵌段共聚物的一个有趣和重要的应用是作为模板，用于制造用于制造微芯片的纳米级特征。该项目将发展关于这种嵌段共聚物中发生的自组装过程的基础知识，以便为制造下一代微芯片和其他有序纳米结构材料设计材料和工艺。利用嵌段共聚物微相分离技术形成具有可控纳米级形貌的聚合物薄膜，为半导体制造、燃料电池和电池以及太阳能等领域的问题提供了潜在的解决方案。定向自组装(DSA)方法提供了利用嵌段共聚物薄膜与非均相图案化界面的相互作用来引导嵌段共聚物微相以长程有序的方式组装成所需的取向的可能性。虽然到目前为止，大多数工作都集中在具有相似嵌段性质的“对称”嵌段共聚物(例如PS-b-PMMA)，但具有较大内聚能差异(即高聚合物Flory-Huggins chi值)的嵌段共聚物有兴趣实现具有较小特征尺寸的微相分离形态。这种“不对称”嵌段共聚物及其相行为还没有被很好地理解。在本项目中，将使用一个新的介观分子动力学模型，该模型可以准确地再现具有不对称嵌段相互作用的现实嵌段共聚物的性质和行为，以了解此类材料的本体和薄膜行为，特别是在DSA应用方面。通过将模型结果与高CHI嵌段共聚物薄膜DSA系统的实验数据进行比较，验证了该模型工作的有效性。这项工作的学术价值大致可以定义为：(1)建立快速有效的嵌段共聚薄膜行为预测工具；(2)阐明聚合物组成和嵌段能量学、界面组成和结构以及薄膜厚度等因素对微相分离嵌段共聚薄膜形态和性能的影响。这项活动产生的更广泛的社会影响包括：(1)为从水分离到有机光伏等各种领域的嵌段共聚物薄膜材料的一般设计奠定了方法和数据的基础；(2)推动开发用于制造下一代集成电路的DSA图案化方法；(3)开发嵌段共聚物的计算材料建模工具；(4)加强本科生和研究生阶段在科学和工程方面未被充分代表的少数群体的教育；(5)培训K-12科学教师；(6)通过童子军和童子军计划对K-12学生进行STEM教育。

1512517 - HendersonA special form of polymer that can be tailored to have very unique properties is commonly referred to as a block copolymer. Block copolymers are made by simply joining two different types of polymer chains together. Since different types of polymers do not like to mix, much like oil and water separate, the two different polymer chains or blocks also try to separate from one another but can only move apart at distances comparable to the length scale of the polymer molecules since they are bonded together. This naturally gives rise to materials possessing structure and order at nanometer length scales. These phase separated and ordered block copolymers can have very unique properties because of this micro- and nanostructure. One interesting and important application for such ordered block copolymers is as templates for making the nanometer scale features used to build microchips. This project will develop the fundamental knowledge about the self-assembly process that occurs in such block copolymers to allow materials and processes to be designed for manufacturing next generation microchips and other ordered nanostructured materials. The use of block copolymer micro-phase separation to form polymer thin films with controlled nanoscale morphologies offers potential solutions to problems in diverse fields, including semiconductor manufacturing, fuel cells and batteries, and solar energy. Directed self-assembly (DSA) methods offer the possibility to use the interaction of a block copolymer thin film with heterogenous patterned interfaces to guide assembly of the block copolymer microphases into desired orientations with long range order. While most work to date has focused on "symmetric" block copolymers with similar block properties (e.g. PS-b-PMMA), block copolymers that possess large differences in their cohesive energy differences (i.e. high polymer Flory-Huggins chi values) are of interest to achieve micro-phase separated morphologies with smaller feature sizes. Such "asymmetric" block copolymers and their phase behavior are not yet well understood. In this project, a new meso-scale molecular dynamics model that can accurately reproduce the properties and behavior of realistic block copolymers possessing asymmetric block interactions will be used to understand the bulk and thin film behavior of such materials, particularly with respect to DSA applications. This modeling work will be validated by comparison of model results with experimental data from high chi block copolymer thin film DSA systems. The intellectual merits of the proposed work can broadly be defined as: (1) establishment of fast and efficient tools for predicting behavior of block copolymer films, (2) elucidation of the impact of factors such as polymer composition and block energetics, interface composition and structure, and film thickness on the morphology and properties of microphase separated block copolymer thin films. The broader societal impacts of this activity include: (1) forming the foundation of methods and data that enable general design of block copolymer thin film materials for a range of fields from water separation to organic photovoltaics, (2) advancing the development of DSA patterning methods for fabrication of next generation integrated circuits, (3) developing computational material modeling tools for block copolymers, (4) enhancing under-represented minority education in science and engineering at the undergraduate and graduate level, (5) training of K-12 science teachers, and (6) STEM education K-12 students through the Cub Scout and Boy Scout NOVA program.