Directed Self-Assembly of Block Copolymers Under Dynamic and Orthogonal Fields

从技术角度来看，控制自组装嵌段共聚物（BCP）中的有序性的需要是公认的。与此同时，人们对BCP在外场作用下进行自组装的复杂场-物质相互作用和动力学的理解也不完全。该项目的总体目标是建立一个知识体系，使高保真度控制的取向和位置顺序的BCP纳米结构的应用程序的外部领域，并了解这种行动的机制。具体地说，这项工作涉及：（1）使用磁场，其强度和方向以及时间和/或位置的函数，所谓的动态场，和（2）使用一个以上的外部场，其中场沿沿着垂直方向作用，所谓的正交场。这项工作将通过开发新的材料和方法来完成，这些材料和方法允许在磁场下快速双轴对准BCP，并将多个场有效耦合到单个系统。将设计和合成显示顺磁行为和/或双轴有序的新BCP，以实现快速双轴对准。新的方法将开发的基础上使用纳米粒子的动态场研究的外部磁场的局部扰动。仪器的设计将使在剪切和磁场同时作用下的自组装研究成为可能。具体目标是：（1）开发具有双轴有序性和顺磁性的BCP，（2）开发和研究动态磁场导向的自组装，以及（3）正交磁场和流场下定向自组装的研究。嵌段共聚物代表了一类技术上重要的合成材料，由两种或多种不同类型的相互连接的聚合物分子组成。根据每个聚合物分子的化学性质，所得材料由具有约3-100纳米尺寸的规则排列的结构组成。从技术角度来看，控制这些结构的位置和对准的能力是非常期望的。令人信服的例子包括这种对齐的嵌段共聚物用于能量产生（例如光致发光）和水净化的应用。该项目解决了目前的差距，无论是在能力和基本理解的对齐嵌段共聚物材料使用外部领域，如电场或磁场。因此，它能够影响或促进具有社会影响的广泛技术，如上文所述。该项目涉及广泛的影响，包括本科生和研究生的课程开发，通过科学博览会和科学途径计划的K-12推广活动，以及与科学教师的夏季研究项目。PI将与其他利益攸关方合作，采取具体举措，改善代表性不足群体的招聘工作。

TECHNICAL SUMMARYThe need to control order in self-assembled block copolymers (BCPs) is well recognized from a technological perspective. At the same time, there is incomplete understanding of the complex field-matter interactions and dynamics with which BCPs undergo self-assembly under the action of external fields. The overall objective of this project is to build a body of knowledge that enables high fidelity control of orientational and positional order of BCP nanostructures by the application of external fields and to understand the mechanisms of such action. Specifically, this work pertains to: (1) the use of magnetic fields which vary in their intensity and direction and a function of time and/or location, so called dynamic fields, and (2) the use of more than one external field where the fields act along perpendicular directions, so called orthogonal fields. This work will be accomplished by the development of new materials and methods which permit fast biaxial alignment of BCPs under magnetic fields and effective coupling of multiple fields to a single system. New BCPs that display paramagnetic behavior and/or biaxial order will be designed and synthesized, to enable fast, biaxial alignment. New methods will be developed based on local perturbation of external magnetic fields using nanoparticles for dynamic field studies. Apparatus will be designed to enable studies of self-assembly under the simultaneous action of shear and magnetic fields.The specific objectives are: (1) development of BCPs that exhibit biaxial order and paramagnetic properties, (2) development and study of dynamic magnetic field-directed self-assembly, and (3) investigation of directed self-assembly under orthogonal magnetic and flow fields.NON-TECHNICAL SUMMARYBlock copolymers represent a technologically important class of synthetic materials and are made up of two or more different types of polymer molecules connected to each other. Depending on the chemical nature of each of the polymer molecules, the resulting materials consist of regularly arranged structures having dimensions of around 3-100 nanometers. The ability to control the position and alignment of these structures is highly desirable from a technological perspective. Compelling examples include applications of such aligned block copolymers for energy generation (e.g. photovoltaics) and water purification. This project addresses current gaps both in capability and fundamental understanding of alignment of block copolymer materials using external fields such as electric or magnetic. As such, it is in a position to impact or facilitate a broad spectrum of technologies with societal impact such as those mentioned above. This project involves a wide range of broader impacts including curriculum development for undergraduate and graduate students, K-12 outreach activities through Science Fair and Science Pathways programs, and summer research projects with science teachers. The PI will embark on specific initiatives aimed at improving recruitment of under-represented groups in collaboration with other stakeholders.