Facile and direct synthesis of oligocarbonate diols from carbon dioxide and their application as sustainable feedstock for polyurethane

Abstract

Oligocarbonate diols (PPCDL) with carbonate content higher than 90% were successfully synthesized by the direct copolymerization of propylene oxide (PO) and carbon dioxide (CO2) using metal-free Lewis acid-base catalysts in the presence of 1,4-butanediol (BDO) as proton exchange agent (PEA). The effects of molar ratio of PO to BDO, temperature, pressure and reaction time on the copolymerization were systematically investigated. The molecular weight of the prepared oligocarbonate diols is in good linear relationship to PO/BDO feeding ratio and can be easily and precisely controlled in the range of 1000–4000 g mol−1. The detailed structures of the oligocarbonate diols were fully investigated by 1H NMR, 13C NMR, MALDI-TOF analysis. The rheological properties of synthesized PPCDL were also studied using a rheometer. Finally, polycarbonate urethanes were designed and successfully prepared using the PPCDLs as soft segment and 4,4′-diphenylmethane diisocyanate (MDI) and BDO as hard segment. The comprehensive evaluation of thermal and mechanical properties of the synthesized poly(carbonate urethane)s (PCUs) demonstrates their complete feasibility in the application of polyurethane industry.