Towards Truly Sustainable Polymers: A Metal-Free Recyclable Polyester from Biorenewable Non-Strained -Butyrolactone

The first effective organopolymerization of the biorenewable non-polymerizable -butyrolactone (-BL) to a high-molecular-weight metal-free recyclable polyester is reported. The superbase tert-Bu-P-4 is found to directly initiate this polymerization through deprotonation of -BL to generate reactive enolate species. When combined with a suitable alcohol, the tert-Bu-P-4-based system rapidly converts -BL into polyesters with high monomer conversions (up to 90%), high molecular weights (M-n up to 26.7kgmol(-1)), and complete recyclability (quantitative -BL recovery).