Chemically recyclable polyurethanes based on bio-renewable γ-butyrolactone: From thermoplastics to elastomers

The large-scale production and disposal of petroleum-derived commercial polyurethane materials have caused severe enviroment problem. Although the bio-based or biodegradable polyols have attracted considerable attention to prepare sustainable polyurethanes, the chemical recycling of polyurethanes via controlled bond scission reactions to recover monomer or value-added building blocks still remains as a big challenge. In this contribution, we address this challenge by preparation of biodegradable and chemically recyclable polyurethanes using bio-based telechelic hydroxyl terminated poly(γ-butyrolactone) (PγBL) diols as precursors. The obtained polyurethanes exhibited thermoplastic or elatomeric properties depending on the molar mass of used PγBL diol precursors. The thermal, mechanical and hydrolytic properties of PγBL based polyurethanes are systematically investigated. Remarkably, the polyurethanes are capable of chemical recycling to recover γBL with high purity in an almost quantitative yield by a simple vacuum distillation procedure.