Polymer-to-Polymer Transformations to Reduce Plastic Waste

Polymer-to-Polymer Transformations to Reduce Plastic Waste art

Overview: Multiple strategies are required to address the mounting issues of plastic waste and climate change. We propose to transform various polyethylenes and polypropylenes into higher-value functionalized polymers. In contrast to polymer deconstruction into smaller molecules, this strategy aims to maintain high molecular weights during the chemical transformations. To attain commercial significance, just 2-6 mol% of monomeric units need to be functionalized. By starting from polymer feedstocks rather than petroleum-based feedstocks, we intend to reduce the energy consumption and greenhouse gas emissions needed to deliver these valuable polymers.

We propose a variety of synthetic strategies to install functional groups onto polymers with minimal molecular weight change. In Aim 1, we propose a two-step process that first converts carbon-carbon single bonds into carbon-carbon double bonds by designing new catalysts for either direct dehydrogenation or a tandem halogenation/elimination route. Second, the carbon-carbon double bonds will be used to install the desired functional group epoxidation, dihydroxylation, hydrocarboxylation, and hydroesterification reactions. In Aim 2 we focus on direct polymer-to-polymer conversion via metal C-H activation, particularly homogeneous catalysts with oxygen for hydroxylation and with carbon monoxide for carboxylation. Aim 3 explores photochemical methods for C-H cleavage for direct functionalization of polyolefins. Across the three aims, reaction pathways and kinetics will be studied, both computationally and experimentally, to inform new catalyst design and reaction optimization. Our initial focus will be linear polyethylenes, followed by other grades of polyethylene and their mixtures. We will measure the physical properties of the functionalized polymers emphasizing their value-added properties.

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