Design of Plurifunctional Cyclocarbonates and their Use as Precursors of Poly(hydroxyurethane) Thermosets: A Review

Polyhydroxyurethanes (PHUs) are promising polymers to replace polyurethanes (PUs), classically obtained by the isocyanate-alcohol route. Various application fields of PUs, for example, foams or coatings, require the use of thermosetting polymers. Hence, a great deal of effort is devoted to the development of PHU thermosets in the recent literature. This review highlights the different strategies developed through the years to synthesize plurifunctional cyclic carbonates, also called poly(cyclic carbonate)s, and whose functionality ≥3 is a prerequisite for the synthesis of thermosetting PHUs. A special emphasize is accorded to the safe and eco-friendly synthetic approaches (e.g., phosgene-free, use of renewable reactants). In addition, the curing strategies implemented to overcome the low reactivity of the monomers and the limitations related to the transitions of the growing networks (i.e., viscosification, gelation, vitrification) are described. In the end, the curing of PHUs under mild thermal conditions, down to room temperature, is described. Such curing conditions are uncommon for PHU thermosets and are paving the way to much anticipated applications such as coatings, adhesives, or 3D-printing.