CAS: Augmenting the Applicability and Sustainability of Direct Arylation Polymerization (DArP)

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教授正在研究绿色和节能的方法来制备共轭聚合物。这类有机半导体在传感器、太阳能电池和发光二极管等各种光电子应用中显示出了巨大的前景。在这项研究中，将进行系统的研究，以提高直接芳基化聚合的可持续性，直接芳基化聚合是一种可控的、原子经济的合成共轭聚合物的方法。重点将放在对绿色溶剂中这一催化过程的机理的理解上，并开发产生官能团耐受性的合理方法。这两种方法的结合有可能改变共轭聚合物的可持续性、可及性和可扩展性。从长远来看，这可能导致具有以前无法获得的分子结构和性能的聚合物的实际大规模生产。这项工作的更广泛影响将通过一整套活动加以展示。参加南加州大学-塞里托斯社区学院实习计划将需要接待社区大学的学生，提供一种有效的方式，主要是接触代表不足的群体。这项实习计划将扩大到洛杉矶皮尔斯学院的学生，该学院是HACU成员拉美裔服务机构的成员。此外，还将开发一个以写为学的教学方法，以促进学生在本科理科课程中的学习和保持。尽管共轭聚合物(CPS)应用的快速增长引起了该领域的越来越多的关注，但目前的合成方法已经落后于持续发现的需要，以及合成聚合物化学中对可持续工艺和材料的日益关注。该项目将重点解决直接芳基化聚合(DARP)中的不足，有可能将这种聚合转变为一种可控、可持续、可扩展和广泛范围的制备CP的方法。在第一个目标中，DARP的机理特征将在二氢左旋葡萄糖酮中进行研究，二氢左旋糖苷酮是一种从纤维素中提取的生物基溶剂，被归类为二甲基甲酰胺的替代品。其他绿色聚合方法包括多相乳液聚合，使用富含稀土的金属进行催化，以及降低反应温度。第二个目标将探索在DARP中实现可控链增长的策略，方法是将催化剂转移直接芳基化条件转录为使用荧四氟苯单体和各种卤代芳烃作为引发剂的聚合。第三个目标是针对反应条件来增加DARP的官能团耐受性。这是通过集中于含酸性/反应性和钯配位官能团的CPS来实现的。这项研究中概述的可持续方法的广泛范围有可能提供有助于更可持续的链增长聚合过程的总体上的进展。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 studying green and energy efficient methods to prepare conjugated polymers. This class of organic semiconductors has shown a great promise for a diverse array of optoelectronic applications, such as sensors, solar cells and light emitting diodes. In this research, systematic studies will be conducted in order to enhance the sustainability of direct arylation polymerization, a controlled and atom-economical method to synthesize conjugated polymers. Strong emphasis will be placed on mechanistic understanding of this catalytic process in green solvents and development of rational methods for engendering functional group tolerance. The combination of these two approaches has the potential to transform the sustainability, accessibility and scalability of conjugated polymers. In the long run, this could lead to practical large-scale production of polymers with previously inaccessible molecular structures and properties. Broader impacts of this work will be demonstrated through integrated set of activities. Participation in the University of Southern California-Cerritos Community College Internship Program will entail hosting community college students, providing an effective way to engage primarily under-represented groups. This internship program will be extended to involve students from Los Angeles Pierce College, an HACU Member Hispanic Serving Institution. Additionally, a pioneering program focused on Write-to-Learn pedagogies to facilitate student learning and retention in undergraduate science classes will be developed.While the rapidly increasing performance of applications of conjugated polymers (CPs) has brought increased attention to the field, current synthetic approaches have lagged behind what is required for continuing discoveries and the increasing focus on sustainable processes and materials in synthetic polymer chemistry. This project will focus on addressing deficiencies in direct arylation polymerization (DArP), with the potential to transform this polymerization into a controlled, sustainable, scalable, and broad-scope method for preparing CPs. In the first objective, mechanistic features of DArP will be investigated in dihydrolevoglucosenone, a bio-based solvent derived from cellulose and classified as an alternative to dimethylformamide. Other green methods for the polymerization will involve heterogenous emulsion polymerization, use of earth-abundant metals for catalysis, and lowering of reaction temperature. The second objective will explore strategies to achieve controlled chain-growth in DArP by transcribing catalyst-transfer direct arylation conditions to polymerizations using a fluorene-tetrafluorobenzene monomer and a variety of halogenated aromatics as the initiators. The third objective targets reaction conditions to increase the functional group tolerance of DArP. This is to be achieved by focusing on CPs bearing acidic/reactive and palladium-coordinating functional groups. The broad scope of sustainable approaches outlined in this research has the potential to provide advances that can contribute to more sustainable chain-growth polymerization processes in general.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.