Carbon Dioxide for Producing Non-Isocyanate Polyurethane Foams, Adhesives, Hydrogels and—Much More!

The recycling of carbon dioxide (CO2) by transforming this waste into value has become a major goal in contemporary science. Strategies are emerging to turn this renewable carbon feedstock into valuable engineering plastics while diversifying renewable resources for the sustainable production of consumer materials. Novel routes to efficiently turn CO2 into polymers are expected to accelerate and facilitate the transition from existing fossil-based to future generations of more sustainable materials while trying to meet the requirements of a circular economy for consumer plastics.
In the first part of this talk, we will discuss how CO2 can be converted into monomers that are then involved in step-growth copolymerizations with diamines to produce non-isocyanate polyurethanes (NIPUs), greener variants of conventional polyurethanes that are commonly prepared by the toxic isocyanate chemistry. These monomers can be easily and quantitatively produced at the multi-kg scale under solvent-free conditions in our lab. We will show how they can be exploited to design some representative high performance NIPUs materials. We will first discuss how adhesives and coatings can be produced under solvent-free conditions, with adhesion performances on various substrates (aluminum, wood, stainless steel, glass) that compete to those of commercial products, provided that appropriate curing is applied. We will then report on an innovative robust and solvent-free process for the construction of flexible or rigid self-blown NIPU foams that offers the first realistic alternative to the traditional isocyanate route. In this process, the CO2-based monomer is not only exploited to construct the NIPU matrix but also for its self-blowing. If time permits, we will also show that NIPUs hydrogels can be produced in water at room temperature without any catalyst with impressive short gel times. These hydrogels can be easily reinforced by introducing natural polymers or clay in the formulations prior to curing. All these technologies can be easily scaled-up and are highly versatile, opening new opportunities in the design of more sustainable materials while valorizing CO2 as a renewable carbon feedstock.
In the second part of the talk, we will describe an innovative approach for the facile preparation of new regioregular functional NIPUs (e.g. poly(oxo-urethane)s and poly(oxazolidone)s) at room temperature by using a novel family of monomers prepared by the CO2 chemistry. The special reactivity of these monomers will be discussed, and if time permits, we will show how they can be exploited for the facile construction of other relevant polymers (e.g. polycarbonates, sulfur-containing polymers) under mild operating conditions.