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

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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.