Terpolymerizations of CO₂, Propylene Oxide, and Various Epoxides Using a Cobalt(III) Complex of Salen-Type Ligand Tethered by Four Quaternary Ammonium Salts

Abstract

Terpolymerizations of CO2/propylene oxide (PO)/cyclohexene oxide (CHO), CO2/PO/1-hexene oxide (HO), and CO2/PO/1-butene oxide (BO) were carried out without the formation of cyclic carbonates and ether linkages with a cobalt(III) complex of a Salen-type ligand tethered by four quaternary ammonium salts (1). The activities were excellent, in the range of (0.62−1.6) × 106 g/mol-Co (TOF, 4400−14 000 h−1). In all three of terpolymerizations, the data for the PO mole fractions in the feed (fPO) and the polymers (FPO) fit the Fineman−Ross plot well to determine the monomer reactivity ratios. The linear dependencies of the Tg’s of the polymers on the mole fractions of the third monomers (FCHO, FHO, and FBO) were observed with the relationships of “Tg (°C) = 81 × FCHO + 40”, “Tg (°C) = −62 × FHO + 38”, and “Tg (°C) = −27 × FBO + 38”, respectively. The decomposition temperature of the resin increased when the third monomer was employed. The GPC data indicated that the polymer chains grew in an immortal passion from four 2,4-dinitrophenolates as well as the two 2,4-dinitrophenols in 1. High molecular weights (Mn) above 200 000 were attainable because of the high activities.