Synthesis and characterization of fully biobased and reprocessable polyurethane foams

Polyurethanes (PU) are one of the most used polymer in the world in many applications but especially as foams with two thirds of the 18 Mt produced per year, representing a market of more than $26 Billion in 2019. They are obtained from the reaction of diisocyanates with polyols, the large panel of available structures of these monomers leads to soft or rigid foams, which find their applications as thermal insulation, bed mattresses or automotive seats... Biobased polyols are very common nowadays but it is still not the case for polyisocyanates, very few are actually available. For that reason, polyurethane foams are only partially biobased. Therefore, the synthesis of fully biobased PU foams still stay a major challenge to this field.
In the course of our study, PU foams were synthesized using biobased polyols derived from fatty acids and saccharides. The foaming process was ensure with the reaction of two of the few commercially available biobased polyisocyanates with water, allowing the release of CO2, while cross-linking with polyols. The effects of monomer structures on the foam properties were studied. The formulation study allowed the synthesis of fully biobased foams with a panel of mechanical properties, which were characterized, ranging from rigid to soft ones. Moreover, transcarbamoylation was used to reprocess the foams by compression molding, in the pursuit of a greener consumption model. Polyurethanes foams were reshaped as bulk PU, which were then also reprocessed up to five cycles.