New Strategies for Regulating Non-Living Olefin Polymerization Catalysis

调控非活性烯烃聚合催化的新策略

• 批准号: 2154532
• 负责人: Loi Do
• 金额: $ 48.78万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-01 至 2025-11-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2154532&HistoricalAwards=false
• 关键词: New; Strategies; Regulating; Non; Living

With the support of the Chemical Catalysis program in the Division of Chemistry, Loi Do of the University of Houston is studying how to improve the synthesis of polyolefins, polymers that account for more than 60% of plastics used worldwide. Polyolefins are some of the most attractive synthetic materials known because of their light weight, resistance to damage by water, oil, and solvent, and ability to be easily shaped into consumer items. A large percentage of polyolefins are made using a catalytic process known as living polymerization. However, such processes are inefficient because only one polymer chain is produced for each catalyst reactive site. In contrast, polymerizations using non-living catalysts yield many polymer chains per site. The main limitation with the non-living catalysts is that it is difficult to control the polymer products they generate. The Do team's research will focus on using earth abundant metal additives to modify non-living polymerizations. This work seeks to develop more sustainable ways to synthesize polyolefins and provide access to previously unknown polymer structures with technologically useful properties. The objective of the Do team's outreach activities is to enhance the research experiences of undergraduate students in the Gulf Coast region of the United States by creating a Texas Chemistry Consortium focused on sharing scientific resources and expertise, exchanging students for training, hosting site visits, and creating professional networking opportunities for students.Under this research project, the Lo group at the University of Houston strives to improve catalytic efficiency and precision in polyolefin synthesis. Polyolefins can be synthesized from olefin monomers using either living or non-living catalysts. Living catalysts provide excellent control over the chain growth process but yield only a single polymer chain per metal. In contrast, non-living catalysts lack control over polymer chain propagation but afford many polymers per metal. Because polyolefins derived from living catalysts contain high metal content, they must also be subjected to further purification steps. To combine the benefits of both living and non-living reactions, Dr. Do and his team are developing a cation-based strategy to regulate polymerizations by coordination insertion catalysis. Under dynamic switching conditions, polymer chain growth occurs from a single catalyst that continuously interconverts between the monometallic and bimetallic forms. The key to success is that cation exchange must proceed slower than chain growth but faster than chain termination. The Do group is also designing new catalysts to achieve stereocontrolled polymerization of functional olefins. A library of chiral catalysts will be assembled by pairing chiral metal auxiliaries with a common catalyst platform, which will provide access to molecular structures that are inaccessible using conventional organic scaffolds. Because polyolefins represent greater than 60% of the commercial plastic produced around the world, improvements in the way they are manufactured on an industrial scale could dramatically reduce cost, energy, and environmental impact.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.

在化学催化计划中，休斯敦大学的LOI DO在研究中如何改善聚合物的合成，这些聚合物占全球使用的塑料的60％以上。聚芬蛋白是一些最有吸引力的合成材料，因为它们的重量轻，水，油和溶剂的损害，以及容易被塑造成消费物品的能力。使用称为活聚合物化的催化过程制成了很大一部分聚集蛋白。但是，这样的过程效率低下，因为每个催化剂反应性位点仅生产一个聚合物链。相反，使用非生存催化剂的聚合会产生每个位置的许多聚合物链。非生存催化剂的主要局限性是很难控制它们产生的聚合物产品。 DO团队的研究将着重于使用地球丰富的金属添加剂来修改非生存聚合物。这项工作旨在开发更可持续的方法来综合聚集蛋白，并提供具有技术有用特性的以前未知的聚合物结构。 DO团队外展活动的目的是通过创建一个专注于共享科学资源和专业知识的德州化学联盟，交换培训，举办现场就诊和交换学生，以增强美国墨西哥湾沿岸地区的本科生的研究经验。为学生创造专业的网络机会。在这项研究项目中，休斯顿大学的LO小组致力于提高聚烯烃合成中的催化效率和精度。可以使用生物或非生存催化剂从烯烃单体合成聚芬蛋白。活催化剂可以很好地控制链生长过程，但每种金属仅产生一个聚合物链。相反，非生存的催化剂缺乏对聚合物链传播的控制，但每种金属都提供许多聚合物。由于源自活催化剂的聚芬蛋白包含高金属含量，因此还必须采取进一步的纯化步骤。为了结合生活和非生命反应的好处，Do博士及其团队正在制定基于阳离子的策略，以通过协调插入催化来调节聚合。在动态切换条件下，聚合物链的生长是由单个催化剂发生的，该催化剂在单元金属和双金属形式之间连续互连。成功的关键是，阳离子交换必须比链的增长慢，但比链条终止更快。 DO组还设计了新的催化剂，以实现功能性烯烃的立体控制聚合。手性催化剂库将通过将手性金属辅助设备与公共催化剂平台配对来组装，该平台将提供使用常规有机脚手架无法访问的分子结构。由于聚烯烃占全球生产的商业塑料的60％以上，因此它们以工业规模制造的方式的改进可以大大降低成本，能源和环境影响。这项奖项反映了NSF的法定任务，并被认为值得一提通过基金会的智力优点和更广泛的影响评估标准通过评估来支持。