In-Situ Studies of the Electrochemical Deposition of Functionalized Poly(thiophene) Copolymers

某些被称为共轭聚合物的有机“塑料”材料能够以类似于传统金属和半导体的方式传导电荷。这些物质在包括能源储存、化学传感器和生物医学设备在内的各种应用中具有相当大的科学和商业价值。然而，这些材料从小分子液体转变为聚合物固体的基本机制尚不清楚。缺乏科学的理解限制了为特定目的精确定制这些材料的能力。现在有专门的电子显微镜样品阶段，可以对这些材料的形成进行详细的局部研究，揭示这个复杂过程中以前未知的方面。该项目将使用高分辨率电子显微镜和相关分析技术，监测材料从前驱体液体，通过粘性中间体，到最终固体共轭聚合物产品过程中形成的反应产物的局部形状和化学性质。这项工作还将使材料科学与工程专业的研究生能够获得专门的高级教育，并对利用电化学反应从小分子形成聚合物建立新的见解。先前已经建立了原位，环境控制的电子显微镜样品级可用于直接监测从液体有机单体3,4-乙烯二氧噻吩（EDOT）溶液到最终聚（3,4-乙烯二氧噻吩）（PEDOT）共轭聚合物产品的电化学转变，使用低剂量透射电子显微镜（TEM）。然而，关于这一过程的许多基本问题仍然未知，包括共聚物的影响和在反应介质中引入固体纳米颗粒。该研究项目将量化这些化学和组成变化对沉积过程的影响，特别是当使用更亲水的共聚物（edo酸）时，低聚物液滴的成核、生长和再溶解回溶液中。TEM实验将辅以能够提供与反应相关的化学变化的额外信息的方法，包括光学显微镜、纳米级FTIR/AFM和微聚焦拉曼光谱。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

PART 1: NON-TECHNICAL SUMMARYCertain organic "plastic" materials known as conjugated polymers are able to conduct electrical charge in a manner similar to traditional metals and semiconductors. These substances are of considerable scientific and commercial interest for a wide variety of applications including energy storage, chemical sensors, and biomedical devices. However, the fundamental mechanisms by which these materials transition from small-molecule liquids to polymer solids are not well understood. This lack of scientific understanding limits the ability to precisely tailor these materials for specific purposes. Specialized electron-microscopic sample stages are now available that allow for detailed local studies of the formation of these materials, revealing previously unknown aspects of this complex process. This project will monitor the local shape and chemistry of the reaction products formed as the material proceeds from precursor liquids, through sticky intermediates, to the final solid conjugated polymer products using a high-resolution electron microscope and related analysis techniques. The work will also enable graduate students in materials science and engineering to obtain specialized advanced education and establish new insights about the formation of polymers from small molecules using an electrochemical reaction. PART 2: TECHNICAL SUMMARYIt has been previously established that in-situ, environmentally-controlled electron-microscopic sample stages can be used to directly monitor the electrochemical transition from a solution of liquid organic monomer 3,4-ethylenedioxythiophene (EDOT) to the final poly(3,4-ethylenedioxythiophene) (PEDOT) conjugated polymer product using low-dose transmission electron microscopy (TEM). However many fundamental questions remain unknown about the process, including the influence of comonomers and introduction of solid nanoparticles in the reaction medium. This research project will quantify the influence of these variations in chemistry and composition on the deposition process, particularly the nucleation, growth, and redissolving of oligomer droplets back into solution when using a more hydrophilic co-monomer (EDOTacid). The TEM experiments will be complemented with methods able to provide additional information about the chemical changes associated with the reaction, including optical microscopy, nanoscale FTIR/AFM, and microfocused Raman spectroscopy.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.