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

Abstract

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° OH) content in the reactivity of CO2-polyols; in particular, the low 1° 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° OH content, e.g., 19F NMR spectroscopy indicates that the 1° 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° OH content of 60% was synthesized.