Upgrading CO₂ into novel families of regioregular and functional polymers

Polycarbonates (PCs) and polyurethanes (PUs) belong to some of the world-leading polymers found in many of our daily life applications. PCs are mainly produced by polycondensation of alkylcarbonates/phosgene derivatives with diols at high temperature, or by ring-opening polymerization of 5- or 6-membered cyclic carbonates while PUs are industrially made by polyaddition of diisocyanates with diols. Recent developments in the PUs field deal with the polyaddition of 5-membered dicyclic carbonates with diamines, but this polymerization is much slower compared to the isocyanate route and gave regio-irregular polymers of low molar mass due to the asence of selective ring-opening and the occurrence of side reactions. The polyaddition of dicyclic carbonates with diols would also be attractive to prepare PCs but is challenging due to the poor reactivity of the 5-membered cycles towards alcoholises. Until very recently, using a single 5-membered dicyclic carbonate platform to access various polymer families remained an elusive endeavour. In this talk, we will describe an innovative approach for the preparation of new families of PCs and PUs, by the facile room temperature polyaddition of novel activated CO2-sourced 5-membered biscyclic carbonates with diols (for PCs) or diamines (for PUs). These novel cyclic carbonates are prepared by organocatalyzed carboxylative coupling of CO2 with dialkynols. Although PCs require some organocatalyst to be produced, PUs synthesis do not require any activation. Moreover, this process allows for the synthesis of regioregular functional polymers free of defects and displaying high molar masses (Mn up to 100 kg/mol in some cases). The origin of this unprecedented reactivity will be explained as well as its impact on the polymer structure. We will also show that these novel CO2-sourced monomers can also be exploited to expand their scope of valorization to a fourth family of novel functional polymers, by tuning the nature of the comonomer. We believe that this platform of novel monomers is opening new perspectives in the facile production of novel and/or existing world-class relevant polymers by valorizing CO2 as a renewable feedstock