Renewable Polyether Polyols via the Hydrogenation of Polyesters

Abstract

Polymers are involved in countless products ranging from high-tech materials used in areo-space industry, car parts, electronics to simple consumer goods such as clothing, sports gear, carpets, and various packing materials. As a result, humankind currently produces a previously unmatched amount of plastic waste. A lot of this waste is currently dumped in landfills or "mismanaged". In order to counter-act the pollution of the environment as well as to conserve natural resources several strategies have been proposed and developed for the recycling of polymeric materials depolymerization and mechanical recycling being the most applied. Both approaches have in common that it is very difficult for them to be cost competitive with the production of the virgin polymers. A solution to this dilemma could be "chemical upcycling". In this approach a polymer is converted to a higher value new material. In the case of polyesters, we could show that in the presence of a homogenous ruthenium catalyst and Lewis acids polyesters can be hydrogenated to polyether polyols. The type of Lewis acid and its ratio with respect to the ruthenium were proven to be crucial. Based on mechanistic investigations it was shown that this reaction proceeds via a tandem hydrogenation/etherification process. The obtained polyether polyols are in the right molecular weight range for the use in adhesives.