Developing the Foundation for Novel Light-Responsive Materials: Tuning Physical Properties of Conjugated Polymer Systems by Illumination

非技术概述刺激反应材料根据其环境的变化改变其结构或性能。这项研究计划将考察新型刺激响应性聚合物，其功能和特性可以通过暴露在光中进行控制。这是很有希望的，因为光可以在没有物理接触的情况下远程应用，其强度可以非常逼真地进行调节，并且可以用于为特定用途的材料制作图案。不幸的是，只有几种化合物可以引入到对光有响应的聚合物中。这一研究计划将为开发基于具有电活性的聚合物分子的广泛的新型光响应材料提供基础。可利用的光敏性和可图案化聚合物的增加将为使用受控照明的新应用提供机会，并显著扩展光响应材料的实用性。为应对材料研究领域的重大挑战而准备好的下一代科学家和工程师的劳动力发展和培训将通过这一综合研究和教育计划实现，还将通过让公立高中生在暑期参与动手研究来实现，为大学提供特殊的准备。在国家实验室的中子设施(ORNL和NIST)完成实验将产生进一步的影响，参加该项目的学生将在多用户设施中获得实践经验。该项目还将进一步发展田纳西州的可持续研究基础设施，并将实施以加强未被充分代表的群体参与研究。技术总结本研究计划的主要目标是对共轭聚合物(CP)的光子吸收改变其宏观物理性质的机制有一个基本的了解，以便提供指导方针，以控制和利用这一现象，以实现具有目标特性的新型刺激响应材料。这项研究计划的完成将使人们全面了解共轭聚合物的光子吸收如何改变其在混合物和溶液中的构型、形态、动力学和热力学。在光存在和不存在的情况下，局部电子和结构变化与共混物宏观动态响应的关联将探索分层指导共轭聚合物共混物由于光子吸收而改变宏观行为的基本过程。对CP溶液和共混物的研究将提供在分子水平上控制这种功能反应的指导方针，并提供对控制这种现象的结构和电光过程的基本了解。实验方案、分析和解释也被设计成适用于广泛的共轭聚合物和CP/非CP共混物。中子散射将被用作确定CP混合物和感兴趣的溶液的结构、深度分布和相行为的主要工具。中子的使用简化了从有光到无光的实验条件的变化，因为与类似的光散射实验不同，用泛光灯照射样品不会影响对散射中子的探测。这套实验结果将被解释为阐明指导方针，以便能够合理设计和控制具有目标特性的新型光响应材料。因此，这项研究计划将提供对局部光子吸收在多个长度尺度上转化为宏观物理性质变化的机制的基本理解，目的是提供策略，通过这些策略可以操纵和指导这种意外现象，以生产新的光响应材料。

NON-TECHNICAL SUMMARY Stimuli-responsive materials alter their structure or properties according to changes in their environment. This research program will examine novel stimuli-responsive polymers whose function and properties can be controlled by exposure to light. This is promising because light can be applied remotely without physical contact, its intensity can be tuned with great fidelity, and it can be used to pattern the materials for specific uses. Unfortunately, there are only a few compounds that can be introduced into polymers that are light responsive. This research program will provide the foundation to develop a broad range of new light-responsive materials based on polymer moleculaes that can be electrically active. This increase in available light-sensitive and -patternable polymers will offer the opportunity for new applications using controlled illumination and significantly extend the practicality of light-responsive materials. Workforce development and training of the next generation of scientists and engineers prepared to tackle the grand challenges in materials research will be realized through this integrated research-and-education program and also by engaging public high-school students in hands-on research over summer periods, providing exceptional preparation for college. Further impact will result from the completion of experiments at the neutron facilities at national laboratories (ORNL and NIST) where the students participating in this project will acquire hands-on experience in a multi-user facility. This project will also further develop the sustainable research infrastructure in Tennessee and will be implemented to enhance the participation of underrepresented groups in research.TECHNICAL SUMMARYThe overarching goal of this research program is to develop a fundamental understanding of the mechanism by which photon absorption by conjugated polymers (CP) alters their macroscopic physical properties in order to provide guidelines by which this phenomenon can be controlled and exploited to realize new stimuli-responsive materials with targeted properties. The completion of this research program will provide a comprehensive understanding of how photon absorption by a conjugated polymer alters its configuration, morphology, dynamics and thermodynamics in blends and solutions. Correlation of local electronic and structural changes to the macroscopic dynamic response of the blends in the presence and absence of light will probe the fundamental processes that hierarchically guide the change in macroscopic behavior of conjugated polymer blends as a result of photon absorption. Examination of both CP solutions and blends will provide guidelines to control this functional response on a molecular level and offer a fundamental understanding of the structural and electro-optical processes that control this phenomenon. The experimental protocol, analysis, and interpretation are also designed to be applicable to a broad range of conjugated polymers and CP/non-CP blends. Neutron scattering will be used as a primary tool to determine the structure, depth profile, and phase behavior of the CP blends and solutions of interest. The use of neutrons simplifies the variation in experimental conditions from the presence to the absence of light, as the illumination of the sample with a floodlit beam of light will not impact the detection of the scattered neutrons, unlike a similar light scattering experiment.This suite of experimental results will then be interpreted to elucidate guidelines to enable the rational design and control of novel light-responsive materials with targeted properties. This research program will therefore provide a fundamental understanding of the mechanism by which local photon absorption translates over multiple length scales to a variation in macroscopic physical properties with the goal of providing strategies by which this unexpected phenomenon can be manipulated and directed to produce new light-responsive materials.