CAREER: An Integrated Approach to Understanding and Controlling the Self-Assembly of Rod-Coil Block Copolymers with an Educational Program in Materials Exploration

技术概述：本提案旨在对功能棒圈嵌段共聚物系统的自组装的热力学和动力学作出基本的理解。这项工作特别重要，因为棒圈嵌段共聚物已被建议用于有机光电和生物应用的优化，并且对其自组装特性的预测性理解是迈向应用的必要步骤。例如，最近在这些材料的器件物理方面的突破表明，两个具有不同功函数的导电有机之间的纳米级界面结构在光电电池中分离电子和空穴以获取电压或相反地在产生光所需的重组中起着不可或缺的作用。嵌段共聚物模板技术的直接应用是复杂的，因为经典研究使用的模型聚合物具有高斯链形状，不参与液晶相互作用。虽然在棒圈嵌段共聚物体系中已经观察到许多新的结构，但控制自组装的热力学目前尚不清楚。Segalman小组初步证明了一种弱分离的棒圈嵌段共聚物体系，随着温度的升高，该体系从片层相转变为向列相，再转变为各向同性相，同时遵循聚合物的结垢关系。这个独特的模型系统为探索平衡热力学提供了一个绝佳的机会。控制这种自组装的热力学参数包括嵌段共聚物的偏析强度、棒-棒相互作用和分子几何结构将被研究。薄膜结构在技术上是最相关的，并且将寻求薄膜约束对棒圈嵌段共聚物的影响的理解。CAREER的研究目标是(i)了解棒块对嵌段共聚物自组装热力学的影响，（ii）开发控制这些技术上重要材料的薄膜自组装的方法，以及（iii）通过将拟议的研究与正在进行的教育活动相结合，在更广泛的人群中培养对聚合物科学的兴趣。非技术总结：棒圈嵌段共聚物在优化有机光电器件、生物膜和药物输送应用方面发挥着核心作用。所有这些努力的关键是理解热力学，它控制着聚合物中具有非经典相互作用的纳米级自组装。随着对功能嵌段共聚物纳米尺度图案的控制，这项工作预计将对这一广泛的应用和社区产生重大影响。此外，结构-属性关系是儿童如何发展对周围环境的理解的核心。一个全面的教育计划将利用这种与生俱来的好奇心，向广泛的学生介绍聚合物科学和上面讨论的研究。一位高中物理老师和首席研究员将开发一套动手探索模块，帮助高中新生理解科学的跨学科本质。然后，这些单元将通过与培训国家教师库的探索博物馆教师研究所合办的讲习班，传播给更广泛、更年轻的学生群体。研究成果还将用于改善本科高分子教育，并使本科生和研究生都能接触到涉及自组装聚合物的研究。国际学生还将定期参观实验室，使小组了解现代研究的跨学科和国际性质。

TECHNICAL SUMMARY: This proposal seeks to contribute fundamental understanding regarding the thermodynamics and kinetics of self-assembly of functional rod-coil block copolymer systems. This work is of particular importance since rod-coil block copolymers have been suggested in the optimization of organic optoelectronic as well as biological applications, and a predictive understanding of their self-assembling properties is a necessary step towards application. For instance, recent breakthroughs in the device physics of these materials have demonstrated that the nanometer scale structure of interfaces between two conducting organics of different work function play an integral role in the separation of electrons and holes to harvest voltage in a photovoltaic cell or conversely in the recombination necessary to generate light. Direct application of block copolymer templating techniques is complicated by the fact that classical studies employed model polymers with Gaussian chain shape that did not participate in liquid crystalline interactions. While a number of novel structures have been observed in rod-coil block copolymer systems, the thermodynamics which control self-assembly are currently unclear. Preliminarily, the Segalman group has demonstrated a weakly segregated rod-coil block copolymer system which transitions from lamellar to nematic to isotropic phases with increasing temperature while following polymeric scaling relationships. This unique model system provides an exceptional opportunity to probe equilibrium thermodynamics. The thermodynamic parameters which control this self-assembly including the block copolymer segregation strength, rod-rod interaction, and molecular geometry will be investigated. The thin film architecture is the most technologically relevant, and an understanding of the effects of thin film confinement on rod-coil block copolymers will be sought. The CAREER research goals are to (i) understand the effect of a rod-block on the thermodynamics of block copolymer self-assembly, (ii) develop methods for controlling thin film self-assembly of these technologically important materials, and (iii) to foster an interest in polymer science in a broader population by integrating the proposed research with ongoing educational activities for students at various levels. NON-TECHNICAL SUMMARY: Rod-coil block copolymers play a central role in many recent efforts to optimize organic optoelectronic devices, biological membranes, and drug delivery applications. Critical to all of these efforts is an understanding of the thermodynamics that control nanometer-scale self-assembly in polymers with non-classical interactions. This work is expected to have a significant impact on this broad range of applications and communities as control is gained over the nanoscale patterning of functional block copolymers. Furthermore, structure-property relationships are at the core of how children develop an understanding of their surroundings. A comprehensive educational plan will harness this innate curiosity to introduce a broad spectrum of students to polymer science and to the research discussed above. A high school physics teacher and the principal investigator will develop a set of hands-on exploratory modules that will help high school freshmen understand the interdisciplinary nature of science. These modules will then be disseminated to a broader, younger group of students through workshops with the Exploratorium Teacher Institute which trains a national pool of teachers. The research results will also be employed to improve undergraduate polymer education and to expose both undergraduate and graduate students to research involving self-assembling polymers. International students will also routinely visit the laboratory to expose the group to the cross-disciplinary and international nature of modern research.