CAS: Lewis Pair Catalyst Platform for Functional Polyether Synthesis

该奖项将资助德克萨斯大学奥斯汀分校化学系的纳撒尼尔·林德教授开发用于控制合成聚醚的新聚合技术。聚醚是一类大分子，其中每个重复单元都含有一个碳氧键。它们通常是由称为环氧化物的小环状碳氧化合物制备的。这类聚合物在当今社会正变得越来越重要，因为它们比广泛使用的塑料更容易降解路径，因为主要高聚物链上主要含有碳-碳键。因此，聚醚可能为可回收性问题提供一个可行的解决方案，从环境角度来看，这一问题至关重要。为了加快合成速度，本研究系统地设计了铝基催化剂。新的化学反应很简单，可以转移到世界各地的实验室，这可能会极大地扩大对这些类型聚合物的获取。这项研究通过为不同的本科生和研究生群体提供教育和研究培训，正在产生更广泛的影响。其他外展工作的重点是通过在德克萨斯大学奥斯汀分校的工程介绍日上介绍聚合物化学，与奥斯汀聋人学校和K-8年级的学生进行互动。本研究致力于开发合成功能性聚醚的Lewis对催化剂体系。目前还没有共识的聚合技术可用于聚醚，提供获得具有可控分子量、链端官能度、对单体官能度的良好耐受性以及非专家可获得性的聚合物的途径。本研究旨在通过探索N-Al-Lewis对催化剂的动力学和机理来进一步开发这一工具。系统地探讨了决定Lewis对催化剂环氧化物聚合活性的空间和电子因素。还进行了与Lewis对的形成和结构相关的详细研究。特别强调通过分解产生烷基或氢化物末端聚合物的两性离子中间体和/或不希望发生的环化来研究和消除寄生引发/终止。与这项工作相关的方法引入了一种现成的聚合平台，只需混合两种商业上可获得的化学品。因此，它为技术或基础设施手段有限的新化学家打开了将结构多样化的环氧化物转化为功能和有用的聚合物的大门。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 this award, the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry is funding Professor Nathaniel Lynd of the Department of Chemistry at the University of Texas at Austin to develop new polymerization techniques for the controlled synthesis of polyethers. Polyethers are a class of large molecules in which every repeating unit contains a carbon-oxygen bond. They are typically prepared from small cyclic carbon-oxygen containing compounds called epoxides. This class of polymers is becoming increasingly important in today’s society because they are easier to degrade pathways than widely used plastics that contain mostly carbon-carbon bonds along the main polymer chains. Hence, polyethers might provide a viable solution to the recyclability problem which is of vital importance from an environmental perspective. In this research, catalysts based on aluminum are systematically designed to speed up the synthesis. The new chemical reactions are simple and can be transferred to laboratories around the world, which could greatly expand access to these types of polymers. This research is having a broader impact by providing education and research training to a diverse population of undergraduate and graduate students. Additional outreach efforts are focused on interactions with students from the Austin School for the Deaf and K-8 students through on-campus introductions to polymer chemistry at the Introduce a Girl to Engineering Day at the University of Texas-Austin. This research is focused on development of Lewis pair catalyst systems for functional polyether synthesis. There is currently no consensus polymerization technique available for polyethers that provides access to polymers with controlled molecular weights, chain-end functionality, good tolerance to monomer functionality, and availability to the non-specialist. This research seeks to further the development of such a tool by exploring the kinetics and mechanisms of the N-Al Lewis pair catalysts. Steric and electronic factors that govern Lewis-pair catalyst activity for epoxide polymerization are systematically explored. Detailed studies associated with Lewis pair formation and structure are also conducted. Special emphasis is placed on the investigation and elimination of parasitic initiation/termination through decomposition of a zwitterionic intermediate resulting in alkyl, or hydride terminal polymers, and/or undesirable cyclization. The methodology associated with this work introduces a readily available polymerization platform requiring only mixing of two commercially available chemicals. As such, it opens doors to new chemists with limited technical or infrastructural means to convert structurally diverse epoxides into functional and useful polymers.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.