Reimagining the Platform for Semiconducting Polymers

在化学系大分子、超分子和纳米化学项目的支持下，南加州大学的Barry C. Thompson教授正在开发一种新型的半导体聚合物，方法是用电活性片段修饰商品塑料。半导体聚合物影响着当代能源和电气科学的许多领域。这些长链碳基大分子被广泛应用于太阳能电池、LED屏幕和其他利用电能转化为光的应用中。在这项研究中，电活性段将被连接到由单碳碳键组成的主聚合物骨架上，它们之间具有特定的相对排列。将制备含有具有碳氮键（双键）的小有机分子的片段。当这些键断裂时，它们在聚合物主链的侧链上产生正电荷和负电荷。通过这种化学方法，非金属塑料被转化为导电和吸收光的塑料。如果成功，这项工作将从根本上改变电活性聚合物的方法，提高环境稳定性和机械性能。这项工作将为培养高分子化学的本科生和研究生提供一个优秀的框架。外展和教育活动将侧重于参与南加州大学-喜瑞都社区学院的暑期研究实习计划，并在本科有机化学课程中实施写作学习教学法。通过与德国合作者的国际合作，也有更广泛的影响，为从事这项研究的学生增加了一个特殊的培训经验。本研究将集中于基于非共轭（甲基）丙烯酸酯骨架的半导体聚合物的开发，该骨架含有电子活性垂坠基团。在第一个具体目标中，均聚物的合成将通过控制自由基和阴离子聚合方法进行优化，目的是确定聚合物结构的关键方面对电荷传输的影响，重点关注立体规则性的作用。聚合后的方法，以纳入电活性吊坠将利用酯交换反应和巯基加成反应。第二个目标侧重于基于丙烯酸酯骨架的立体规则嵌段共聚物。最后，通过评估聚合物结构与薄膜形态之间的相关性，探索所制备的多功能聚合物在有机光伏电池中的潜在应用。如果这项研究成功的话，将会促进基础化学知识的发展，即如何利用弹性来帮助将电活性垂坠排列成有序的构象，以促进和提高电子传递效率。从长远来看，这项工作还可以通过卷对卷加工制备柔性，轻质和廉价的有机半导体。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。

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professor Barry C. Thompson of the University of Southern California is developing a new class of semiconducting polymers by decorating commodity plastics with electro-active segments. Semiconducting polymers impact many areas of contemporary energy and electrical science. These long chain carbon-based macromolecules are extensively used in solar cells, LED screens and other applications that utilize the conversion of electricity to light. In this research, electro-active segments will be attached to main polymer backbone consisting of single carbon-carbon bonds with a specific alignment relative to one another. Segments will be prepared that contain small organic molecules featuring carbon-nitrogen pi-bonds (double bonds). When these pi-bonds are broken, they create positive and negative charges along the side chains of the main polymer backbone. With such a chemical approach, non-metallic plastics are converted to plastics that conduct electricity and absorb light. If successful, this work will fundamentally change the approach toward electro-active polymers with improved environmental stability and mechanical properties. This work will provide an outstanding framework for the training of undergraduate and graduate students in polymer chemistry. Outreach and educational activities will focus on participation in the USC-Cerritos Community College summer research internship program and implementation of writing-to-learn pedagogies in undergraduate organic chemistry courses. There is also broader impact through international collaboration with the collaborators in Germany adding a special dimension to the training experience for the students engaged in this research. This research will focus on development of semiconducting polymers based on non-conjugated (meth)acrylate backbones containing electronically active pendant groups. In the first specific aim, the synthesis of homopolymers will be optimized using controlled radical and anionic polymerization methods, with the goal to identify the influence of critical aspects of polymer structure on charge transport with a central focus on the role of stereoregularity. Post-polymerization methods to incorporate electroactive pendants will utilize transesterification and thiol-ene addition reactions. The second aim focuses on stereoregular block copolymers based on acrylate backbones. Lastly, the prepared multi-functional polymers will be explored for potential use in organic photovoltaics by evaluating the correlations between polymer structure and thin film morphology. The proposed research, if successful, will advance fundamental chemistry knowledge on how to use tacticity to assist in the arrangement of the electro-active pendants into an ordered conformation to facilitate and improve electron transport efficiency. In the long run, this work could also enable the preparation of flexible, lightweight and inexpensive organic semiconductors with roll-to-roll processing.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.