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(gamma-butyrolactone) (P gamma BL) diols as precursors. The obtained polyurethanes exhibited thermoplastic or elatomeric properties depending on the molar mass of used P gamma BL diol precursors. The thermal, mechanical and hydrolytic properties of P gamma BL based polyurethanes are systematically investigated. Remarkably, the polyurethanes are capable of chemical recycling to recover gamma BL with high purity in an almost quantitative yield by a simple vacuum distillation procedure.

Automated summary

The large-scale production and disposal of petroleum-derived commercial polyurethane materials have caused severe environmental problems. While bio-based or biodegradable polyols have attracted attention for preparing sustainable polyurethanes, the chemical recycling of polyurethanes to recover monomers or value-added building blocks remains a major challenge. This study addresses this challenge by preparing biodegradable and chemically recyclable polyurethanes using bio-based telechelic hydroxyl terminated poly(gamma-butyrolactone) diols as precursors. The resulting polyurethanes exhibit thermoplastic or elastomeric properties depending on the molar mass of the used diol precursors. The thermal, mechanical, and hydrolytic properties of the polyurethanes based on poly(gamma-butyrolactone) are systematically investigated. Remarkably, these polyurethanes can be chemically recycled to recover gamma-butyrolactone with high purity in almost quantitative yield through a simple vacuum distillation procedure.