Chemo- and regio-selective additions of nucleophiles to cyclic carbonates for the preparation of self-blowing non-isocyanate polyurethane foams

Polyurethane (PU) foams are indisputably daily essential materials found in many applications, notably for comfort (e.g. matrasses) or energy saving (e.g. thermal insulation). Today, greener routes for their production are intensively searched for avoiding the use of toxic isocyanates. We now describe an easily scalable process for the simple construction of self-blown isocyanate-free PU foams by exploiting the organocatalyzed chemo- and regio-selective additions of amines and thiols to easily accessible cyclic carbonates. These reactions are first validated on model compounds and rationalized by DFT calculations. Various foams are then prepared and characterized in terms of morphology and mechanical properties, and the scope of the process is illustrated by modulating the composition of the reactive formulation. Due to the impressive diversity and accessibility of the main components of the formulations, this new robust and solvent- free process is opening avenues for constructing more sustainable PU foams, and offers the first realistic alternative to the traditional isocyanate route.
Introduction