CAS: Mild Methods for the Selective De(hydro)chlorination of Polyvinyl Chloride

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（USC）的Megan Fieser博士和Shaama Mallikarjun Sharada博士正在研究环保途径来重新利用聚氯乙烯（PVC）废物。虽然PVC是一种有价值的聚合物（塑料），在建筑和医疗应用中发挥着关键作用，但盐酸的产生阻碍了普通的回收利用。在这项研究中，将开发催化方法将PVC转化为有用的有机和含氯产品，避免形成有害和腐蚀性化学物质。这些方法旨在改变PVC产品化学回收的可持续性和价值。这项工作的更广泛影响将是支持科学和工程（WISE）的女性研究生，并向公众宣传塑料污染。Fieser博士和Mallikarjun Sharada博士将继续分别担任南加州大学女性化学（WiC）和女性化学工程（WChE）小组的指导教师。海滩清理和外展教育网站将向公众宣传塑料污染的挑战和解决方案。在不产生有害和腐蚀性副产品的情况下，开发环保和可持续的PVC回收、升级和热解工艺对解决塑料废物问题至关重要。通过互补的实验和计算努力，本研究旨在揭示新的均相催化途径，将PVC转化为增值化学品和聚合物。这项工作将侧重于通过催化剂设计和反应条件优化来控制产物选择性，并通过计算分析来支持实验选择。在第一个目标中，PVC的选择性脱氯将留下良性含氯产品和聚乙烯作为有机副产物，可用于现有的回收流。在第二个目标中，将优化脱氢氯化反应，以形成烯烃官能团，而不生成盐酸。串联方法与脱氢氯化将产生功能化聚合物和小分子二烯，代表PVC的可持续升级循环。在第三个目标中，催化机理的计算分析将有助于解释实验结果，筛选催化剂和盐，以指导和加速实验。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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, Dr. Megan Fieser and Dr. Shaama Mallikarjun Sharada of the University of Southern California (USC) are studying environmentally friendly routes to repurpose poly(vinyl chloride) (PVC) waste. While PVC is a valuable polymer (plastic), serving critical roles in construction and medical applications, generation of hydrochloric acid prevents common recycling. In this research, catalytic methods will be developed to convert PVC to useful organic and Cl-containing products that avoid the formation of harmful and corrosive chemicals. These approaches aim to transform the sustainability and value of chemical recycling of PVC products. Broader impacts of this work will be in the support of women in science and engineering (WISE) graduate students and the education of plastic pollution to the general public. Dr. Fieser and Dr. Mallikarjun Sharada will continue to serve as faculty advisors to the Women in Chemistry (WiC) and Women in Chemical Engineering (WChE) groups, respectively, at USC. Beach cleanups and an outreach education website will inform the general public about the challenges of and solutions to plastic pollution.The development of environmentally friendly and sustainable processes for recycling, upcycling, and pyrolysis of PVC without generating harmful and corrosive byproducts is important for addressing the plastic waste issue. Through complementary experimental and computational efforts, this research aims to unveil new homogeneous catalysis routes for repurposing PVC into value-added chemicals and polymers. The work will focus on controlling product selectivity via catalyst design and optimization of reaction conditions, with computational analysis supporting experimental choices. In the first objective, selective dechlorination of PVC will leave benign chlorine-containing products and polyethylene as the organic byproduct, which could be used in existing recycling streams. In the second objective, dehydrochlorination will be optimized to form alkene functional groups without the formation of hydrochloric acid. Tandem methods with dehydrochlorination will lead to functionalized polymers and small molecule dienes, representing sustainable upcycling of PVC. In the third objective, computational analysis of catalytic mechanisms will serve to interpret experimental findings and screen catalysts and salts to guide and accelerate experiment.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.