In-Situ Transmission Electron Microscopy of the Electrochemical Deposition of Functionalized Poly(thiophenes)

本项目将直接监测固体导电聚合物（也称为“合成金属”）从液体溶液的形成，使用特殊的高分辨率电子显微镜，可以直接观察结晶过程的发生。这些有机材料被用于许多先进的应用，包括柔性电池、太阳能电池和生物医学设备。然而，它们复杂的结构在分子水平上形成的方式在科学上还没有得到很好的理解。该项目将研究电化学反应过程中这些复杂材料的形成和生长。实验将使用一个特殊的样品台，这样就可以在电子显微镜下观察和监测材料从液体变为固体的过程。该研究项目将教会材料科学与工程专业的学生如何详细了解电活性聚合物的微观结构与性能之间的关系，并为他们更广泛的跨学科教育做出贡献。本研究项目将利用原位透射电子显微镜（TEM）研究功能化聚噻吩的电化学沉积。共轭聚噻吩，包括聚（3,4-乙基二氧噻吩）（PEDOT）和聚（3,4-丙基二氧噻吩）（PProDOT），具有相当大的科学和商业价值，但详细的电化学沉积机制尚不清楚。原位样品支架将用于直接在TEM中检查从液体单体溶液到固体聚合物的沉积。这些实验将使监测噻吩单体在电极-电解质界面区域的氧化聚合成为可能，提供有关聚合物薄膜结构演变的详细信息，作为传递到电极的总电荷的函数。结果将与使用阻抗光谱和循环伏安法测量电荷输运性质相关联。还将与互补成像技术（包括光学和扫描电子显微镜）获得的图像进行关联。

PART 1: NON-TECHNICAL SUMMARY This project will directly monitor the formation of solid electrically conducted polymers (also known as "synthetic metals") from liquid solutions using a special high-resolution electron microscope which allows direct observation of the cyrstallization process as it takes place. These organic materials are used in many advanced applications including flexible batteries, solar cells, and biomedical devices. However, the way their complicated structures actually form at the molecular level is not well understood scientifically. The project will examine the formation and growth of these complex materials during an electrochemical reaction. The experiments will use a special sample stage that will make it possible to watch and monitor within the electron microscope what happens as the materials change from liquid to solid. The research project will teach students in materials science and engineering how to establish a detailed understanding about the relationship between microstructure and properties of electrically active polymers, as well as contribute to their broader interdisciplinary education. PART 2: TECHNICAL SUMMARY This research project will investigate the electrochemical deposition of functionalized poly(thiophenes) using in-situ transmission electron microscopy (TEM). Conjugated poly(thiophenes), including poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), are of considerable scientific and commercial interest, but the detailed mechanisms of electrochemical deposition are not yet known. An in-situ sample holder will be used to examine the deposition from liquid monomer solution to solid polymer directly in a TEM. These experiments will make it possible to monitor the oxidative polymerization of thiophene monomers in the region of the electrode-electrolyte interface, providing detailed information about the structural evolution of the resulting polymer films as a function of total charge delivered to the electrode. The results will be correlated with measurements of charge transport properties using impedance spectroscopy and cyclic voltammetry. Correlations will also be made with images obtained by complementary imaging techniques including optical and scanning electron microscopy.