Synthesis of CO2-Derived Poly(indene carbonate) from Indene Oxide Utilizing Bifunctional Cobalt(III) Catalysts

The copolymerization of carbon dioxide and indene oxide to yield poly(indene carbonate) has been achieved through the use of bifunctional cobalt(III) catalysts. When compared to our earlier studies utilizing the traditional binary (salen)Co(III)X/cocatalyst system, the bifunctional catalysts display large increases in activity and selectivity for polymer while maintaining good control (PDI < 1.2). The copolymerization reactions can proceed at 25 degrees C while maintaining >99% selectivity for poly(indene carbonate) production. Polymer samples have been achieved with M(n)s and T(g)s of up to 9700 g/mol and 138 degrees C, respectively. This represents the highest T-g yet observed for polycarbonates produced from the coupling of CO2 and epoxides. Additionally, the activation energy for the direct coupling of indene oxide and CO2 to yield cis-indene carbonate employing the (salen)CrCl/n-Bu4NCl catalyst system was determined to be 114.4 +/- 5.7 kJ/mol utilizing in situ ATR-FTIR.