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，巴里C.南加州大学的汤普森正在研究绿色和节能的方法来制备共轭聚合物。 这类有机半导体在各种光电应用中显示出巨大的前景，例如传感器，太阳能电池和发光二极管。 本研究将对直接芳基化聚合这一可控的、原子经济的共轭聚合方法进行系统的研究，以提高其可持续性。 重点将放在对绿色溶剂中的催化过程的机理理解和产生官能团耐受性的合理方法的开发上。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，这可能导致实际的大规模生产具有以前无法获得的分子结构和性能的聚合物。这项工作的更广泛影响将通过一系列综合活动加以展示。 参加南加州大学-喜瑞都社区学院实习计划将需要接待社区学院的学生，为主要是代表性不足的群体提供有效的方式。这个实习计划将扩大到包括来自洛杉矶皮尔斯学院的学生，这是一个HACU成员西班牙裔服务机构。 此外，还将开发一个专注于“写来学去”的开创性项目，以促进学生在本科科学课程中的学习和保留。虽然共轭聚合物（CP）应用性能的迅速提高使该领域受到越来越多的关注，目前的合成方法已经落后于持续发现和日益关注合成聚合物中的可持续工艺和材料的要求化学.该项目将专注于解决直接芳基化聚合（DArP）中的缺陷，并有可能将这种聚合转化为一种可控的，可持续的，可扩展的和广泛的制备CP的方法。 在第一个目标中，将在二氢左旋葡萄糖酮中研究DArP的机制特征，二氢左旋葡萄糖酮是一种来自纤维素的生物基溶剂，被归类为二甲基甲酰胺的替代品。其它的绿色聚合方法包括多相乳液聚合、使用地球上丰富的金属进行催化和降低反应温度。 第二个目标将探讨策略，以实现控制链增长的DArP转录催化剂转移直接芳基化条件下的聚合反应，使用芴-四氟苯单体和各种卤代芳烃作为引发剂。 第三个目标针对反应条件以增加DArP的官能团耐受性。 这将通过关注具有酸性/反应性和钯配位官能团的CP来实现。 在这项研究中概述的可持续方法的广泛范围有可能提供的进步，可以有助于更可持续的链增长聚合过程中generally.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.