A robust and versatile process for converting CO2 into new 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 most often produced by polycondensation of alkylcarbonates with diols at high temperature, or by ring-opening polymerization of 5- or 6-membered cyclic carbonates under milder reaction conditions. PUs are industrially made by polyaddition of diisocyanates with diols, also under mild experimental conditions. Some recent developments in the PUs field deal with the polyaddition of dicyclic 5-membered carbonates with diamines, but this polymerization is much slower compared to the isocyanate route and low molar mass polymers are most often obtained. The polyaddition of dicyclic carbonates with diols would also be attractive to prepare PCs but is not largely exploited due to the poor reactivity of the 5-membered cycles towards alcohols. Although these drawbacks, the 5-membered cyclic carbonates are highly attractive monomers because they can be easily produced at low cost by coupling CO2 with di-epoxides that can be partially or totally bio-sourced (for instance from epoxidized vegetable oils). Until very recently, it was however extremely challenging to produce both PUs and PCs from a single 5-membered dicyclic carbonate under mild experimental conditions.
In this talk, we will describe an innovative process for the preparation of new families of PCs and PUs by the facile organocatalyzed polyaddition of novel CO2-sourced bis(5-membered cyclic carbonate)s with diols (for PCs) or diamines (for PUs) under ambient conditions. These novel cyclic carbonates are prepared by organocatalyzed carboxylative coupling of CO2 with dialkynols. Although PCs require some organocatalyst to be produced at room temperature, PUs do not require any activation. Moreover, this process allows the synthesis of functional polymers with a high regioregularity, no side reaction, and high molar masses can be obtained (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 for the production of other functional polymers, by tuning the nature of the comonomer and the catalyst. We believe that this family of monomers is opening new perspectives in the facile production of important polymers that cannot be produced by the current techniques. Some preliminary applications of these polymers will be discussed.