Ruthenium-catalyzed Chemical Recycling of Poly(ϵ-caprolactone) via Hydrogenative Depolymerization and Dehydrogenative Polymerization

The chemical recycling of end-of-life polymers can be a beneficial part for a future circular chemistry/economy. In this regard, the chemical recycling of poly(ϵ-caprolactone) (PCL) was studied. In more detail, end-of-life PCL was depolymerized by hydrogenation with the aid of catalytic amounts of the commercially available Ru-MACHO-BH complex to generate 1,6-hexanediol. The 1,6-hexanediol was used as starting material to synthesize polyesters based on poly(ϵ-caprolactone) and/or poly(1,6-hexanediol-adipate) in a dehydrogenative polymerization enabled by catalytic amounts of the Ru-MACHO-BH complex. Overall a recycling is feasible.