CO2-based synthons, from the synthesis to the elaboration of low carbon footprint polycarbonates

This research project falls within the framework of CO2 valorization for the development of new monomers and CO2-based polymers (chemical fixation of CO2). Specifically, this project targets the study of the coupling of alcohols and CO2 for the fabrication of low carbon footprint carbonates and polycarbonates. This thesis work revolves around two main stages. The first step is to propose a mechanistic study on the synthesis of (a)cyclic carbonates from alcohols and CO2 in mild conditions (low temperature and pressure). Using kinetic monitoring by in-situ ATR-IR spectroscopy supported by molecular modelling (DFT calculations), a careful comparison of dual organic systems, used as activators of these thermodynamically unfavorable reactions, and their performances on the synthesis of (a)cyclic carbonates is described in details . In particular, reaction mechanisms are identified to better understand the differences observed in reactivity and selectivity. In the second step, the development of CO2- and bio-sourced polycarbonates is studied, especially for the synthesis of isosorbide polycarbonates as promising materials with properties similar to conventional petroleum-based polycarbonates. The direct coupling between isosorbide and CO2 is first studied by varying the experimental conditions. Since this direct copolymerization is very difficult due to the thermodynamic limitations encountered during the alcohol / CO2 coupling, a strategy for synthesizing new monomers from bio-based alcohols and CO2 is then proposed. This new platform of molecules then allows for the synthesis of polycarbonates with tunable chemical structures by melt polycondensation. In this context, an in-depth study of the reactivity of these monomers for obtaining (co)polycarbonates is carried out as well as the physico-chemical characterisations of the synthesized materials.