RUI: Creation and Application of Nucleophile-Induced retro Diels-Alder LinKages in Dynamic-Covalent Polymeric Systems

在这个由化学系高分子、超分子和纳米化学计划资助的项目中，加州理工州立大学圣路易斯奥比斯波分校化学系的Philip Costanzo教授和Daniel Bercovici教授正在开发合成方法，以制备对外部温度响应的新型聚合物。合成聚合物通常被称为塑料，广泛应用于我们的日常生活中。聚合物是由许多通过碳-碳键连接的重复化学单元组成的长链大分子。它们的性能由它们的化学结构控制，可以根据不同的应用进行定制。在这项研究中，首先制备了一些化学上不同的触发温度响应的小分子，并研究了它们的物理性质。这些分子然后在精确的位置结合到聚合物链中。这一有效的策略允许设计具有化学结构的聚合物链，这些聚合物链可以在一个温度下拆分，然后在不同的温度下重新连接起来。与该奖项相关的化学可广泛地转移到许多其他聚合系统，并对材料化学和任何其他对热响应塑料感兴趣的领域有用。这项研究正在产生更广泛的影响，为本科生提供独特的机会，接受有机化学和聚合物化学方面的尖端研究、培训和教育。除了将与该奖项相关的结果纳入该大学的化学实验室课程外，还启动了一项名为社区、资源和外联的高分子联盟(MACRO)的推广计划。该计划的目标是建立一个外展材料的储存库，个人可以通过它向普通民众传播他们对科学的热情和知识。这项工作的重点是开发动态共价键，可以结合到聚合物系统中，使聚合物拓扑结构可切换，并赋予热响应特性。为了实现这一目标，开展了几项研究。第一个目标是开发具有新型双烯和亲双烯化合物的Diels-Alder连接体系，并系统地了解所制备的加合物的热稳定性。在第二个目标中，不饱和加合物正在进行1，4-Michael加成，这有利于逆向Diels-Alder裂解，然后利用铜催化的原子转移自由基聚合将不饱和加合物结合到聚合物结构中。最后一个目的是探索动态共价化学对聚合物拓扑结构和物理性质的影响，特别强调响应性聚合物表面活性剂。使用诸如硫醇之类的亲核试剂来调节断键温度适用于各种其他聚合技术，并有可能产生一系列具有工业重要性的新型智能软材料。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。

In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professors Philip Costanzo and Daniel Bercovici of the Department of Chemistry at the California Polytechnic State University, San Luis Obispo, are developing synthetic approaches to prepare novel polymers that are responsive to externally applied temperatures. Synthetic polymers are commonly referred to as plastics and are widely used in our daily lives. Polymers are long chain macromolecules consisting of many repeating chemical units linked with carbon-carbon bonds. Their properties are controlled by their chemical structures which can be tailored for different applications. In this research, a number of chemically-distinct small molecules that trigger temperature response are first prepared and their physical properties investigated. These molecules are then incorporated into polymer chains at precise locations. This efficient strategy allows the design of polymer strands with chemical structures that can be pulled apart at one temperature and snapped back together at a different temperature. The chemistry associated with this award is broadly transferrable to many other polymerization systems and useful to materials chemistry and any other fields in which thermally-responsive plastics are of interest. This research is having a broader impact by providing unique opportunities for undergraduate students to receive cutting edge research training and education in organic and polymer chemistry. Apart from incorporating the results associated with this award into chemistry laboratory courses at the university, an outreach program called the Macromolecular Alliance of Community, Resources and Outreach (MACRO) is initiated. The goal of this program is to create a depository of outreach materials through which individuals can spread their passion and knowledge of science to the general population. This work is focused on the development of dynamic-covalent linkages that can be incorporated into polymer systems to enable switchability in polymer topology and bestow thermal responsive properties. Several studies are carried out in order to achieve this goal. The first objective focuses on the development of Diels-Alder linkage systems with novel dienes and dienophiles and systematic understanding of the thermal stability of the prepared adducts. In the second objective, the unsaturated adducts are undergoing 1,4-Michael addition which favors the retro-Diels-Alder cleavage followed by incorporation within polymeric structures using copper catalyzed atom transfer radical polymerization. The last aim explores dynamic covalent chemistry effects on the polymer topology and physical properties with special emphasis on responsive polymer surfactants. Using nucleophiles such as thiols to modulate bond-cleaving temperature is applicable to a variety of other polymerization techniques and has the potential to generate a wide range of new smart soft materials of industrial importance.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.