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

在化学系大分子、超分子和纳米化学计划的支持下，南加州大学(USC)的Megan Fieser博士和Shaama Mallikarjun Sharada博士正在研究环境友好型方法，以重新利用聚氯乙烯(PVC)废物。虽然聚氯乙烯是一种有价值的聚合物(塑料)，在建筑和医疗应用中起着关键作用，但盐酸的产生阻碍了常见的回收。在这项研究中，将开发催化方法将聚氯乙烯转化为有用的有机和含氯产品，以避免形成有害和腐蚀性的化学品。这些方法旨在改变聚氯乙烯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妇女攻读科学和工程(WISE)研究生，并对普通公众进行塑料污染教育。Fieser博士和Mallikarjun Sharada博士将继续分别担任南加州大学化学女性(WIC)和化学工程女性(WCHE)小组的教职顾问。海滩清理和外展教育网站将向公众介绍塑料污染的挑战和解决方案。开发环境友好和可持续的流程，回收、更新和裂解聚氯乙烯，而不产生有害和腐蚀性的副产品，对于解决塑料垃圾问题非常重要。通过互补的实验和计算工作，这项研究旨在揭示将聚氯乙烯重新用于增值化学品和聚合物的新的均相催化路线。这项工作将集中于通过催化剂设计和反应条件的优化来控制产品的选择性，并通过计算分析支持实验选择。在第一个目标中，对聚氯乙烯的选择性脱氯将留下良性的含氯产品和聚乙烯作为有机副产品，这些产品可以用于现有的回收流程。在第二个目标中，将优化脱氯化氢反应，在不生成盐酸的情况下形成烯烃官能团。串联脱氯化氢方法将导致官能化聚合物和小分子双烯，代表着聚氯乙烯的可持续上行循环。在第三个目标中，催化机理的计算分析将用于解释实验结果，并筛选催化剂和盐来指导和加速实验。这一奖项反映了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 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.