Propylene oxide end-capping route to primary hydroxyl group dominated CO2-polyol

In the past decade, poly(carbonate ether) polyols, or CO2-polyols, have been synthesized by the copolymerization of CO2 and propylene oxide (PO) with a double metal cyanide (DMC) catalyst in the presence of various chain transfer agents. CO2-polyols show great potential use as substitutes for polyols derived from fossil feedstock in the polyurethane industry. Brookfield viscosity tests have revealed the importance of primary hydroxyl (1 degrees OH) content in the reactivity of CO2-polyols; in particular, the low 1 degrees OH content of CO2-polyols severely limits their application in foam materials. Incorporation of more carbonate linkages has proven to be only moderately efficient for preparing CO2-polyols with high 1 degrees OH content, e.g., F-19 NMR spectroscopy indicates that the 1 degrees OH content of a CO2-polyol can increase from 13% to 39% when the carbonate content in the CO2-polyol is increased from 26.1% to 80.0%. In this study, the PO end-capping route was developed using a strong Lewis acid, such as tris(pentafluorophenyl) borane (FAB) as a catalyst, and a CO2-polyol with 1 degrees OH content of 60% was synthesized.