Two of the major environmental challenges in today’s society are CO₂ emissions and waste management surrounding plastics. The inability to properly recycle plastic materials (polymers) not only creates pollution issues related to microplastics present in our eco-systems, but also directly relates to the carbon emitted causing a major impact on global warming and climate change.

It is thus essential to create new strategies to reduce these negative effects, and chemistry offers a tool to access polymers using circular economy principles, which utilize CO₂ as a reactant. This minimizes our dependency on fossil fuels, while new types of monomers can be made from CO₂ (cyclic carbonates) used to produce degradable polymers within a circular economy approach.

This thesis focuses on computational analysis (DFT) of CO₂ valorization/recycling processes through homogeneous catalysis, and creating a predictive reactivity model. In each chapter, I studied a specific part of process circularity or CO₂ recycling, starting with the conversion of CO₂ into five-membered cyclic carbonates from alkyne-1,2-diols using a Ag catalyst. Then, the creation of larger-ring carbonates (six-membered) from smaller ones is presented via a unique organocatalytic strategy. As these cyclic carbonates can be used as monomers, though not in all cases, I conducted an extensive study of the Ring-Opening Polymerization (ROP) reaction of cyclic carbonates using BnOH as initiator and an organocatalyst. This exploration led to defining a main ROP pathway for a wide range of monomers and model that can predict the polymerization ability of a monomer. Finally, I studied the organocatalyzed depolymerization of a polycarbonate, that selectively breaks down the polymer into a trans-cyclic carbonate, or an epoxide and CO₂. This ultimate study provides deep insights for CO₂ valorization, complemented by experimental results offering a more complete view on how to effective convert and recycle CO₂ within a circular approximation.

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