New Directions for the Synthesis and Degradation of Renewable and Recyclable Plastics Using Homogeneous Catalytic (De)hydrogenation

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Many of the items we use on a daily basis are made of plastics. In particular, certain types of plastics such as polyureas, polyurethanes, and polycarbonates have significant applications in construction materials and the biomedical industry and have a global market value of £86 billion/year. However, their industrial production involves toxic and hazardous starting materials such as diisocyanates and phosgene gas. Thus, the development of greener methods that avoid such fatal starting materials to produce useful plastic is a pressing need of current society. The proposed fellowship aims to develop a new green and sustainable approach for the synthesis of such plastics by the process of dehydrogenative coupling of diols/diamines with methanol. The proposed methodology will substitute the use of deadly reagents (such as diisocyanates, and phosgene gas) with methanol which is not just less toxic and cheaper than the currently used reagents but is also renewable and can be produced from biomass or CO2. The potential applications of the synthesized polymers in multiple areas such as environmental studies, drug delivery, and medical imaging will also be studied in collaboration with experts in the corresponding areas. The success of the research outlined in this proposal will benefit the environment, the economy, and human safety.Another related and serious problem is that of plastic pollution. In fact, more than 1 million birds and over 100,000 sea mammals die from eating or getting tangled in plastic waste. Aside from harming wildlife, plastic waste is an untapped resource, because existing uses for it are few and inefficient. The proposed program will unlock the economic potential of plastic waste by developing a new route for chemical recycling of plastic wastes of type polyureas, polyurethanes, and polycarbonates using the approach of catalytic hydrogenation. Overall, using a combined approach of catalytic dehydrogenation (for the synthesis of plastic) and hydrogenation (for degradation of plastic waste) this program envisions establishing the closed-loop production of plastics to enable a circular economy, which addresses the economic needs of humanity while reducing harm on the biosphere.