title: Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salen)Co(III) complex tethering four quaternary ammonium salts.
abstract: The (salen)Co(III) complex 1 tethering four quaternary ammonium salts, which is a highly active catalyst in CO2/epoxide copolymerizations, shows high activity for propylene oxide/phthalic anhydride (PO/PA) copolymerizations and PO/CO2/PA terpolymerizations. In the PO/PA copolymerizations, full conversion of PA was achieved within 5 h, and strictly alternating copolymers of poly(1,2-propylene phthalate)s were afforded without any formation of ether linkages. In the PO/CO2/PA terpolymerizations, full conversion of PA was also achieved within 4 h. The resulting polymers were gradient poly(1,2-propylene carbonate-co-phthalate)s because of the drift in the PA concentration during the terpolymerization. Both polymerizations showed immortal polymerization character; therefore, the molecular weights were determined by the activity (g/mol-1) and the number of chain-growing sites per 1 [anions in 1 (5) + water (present as impurity) + ethanol (deliberately fed)], and the molecular weight distributions were narrow (M w/M n, 1.05-1.5). Because of the extremely high activity of 1, high-molecular-weight polymers were generated (M n up to 170,000 and 350,000 for the PO/PA copolymerization and PO/CO2/PA terpolymerization, respectively). The terpolymers bearing a substantial number of PA units (f PA, 0.23) showed a higher glass-transition temperature (48 °C) than the CO2/PO alternating copolymer (40 °C).
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749 Korea.
authors.forename: Jong Yeob
authors.initials: JY
authors.lastname: Jeon
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749 Korea.
authors.forename: Seong Chan
authors.initials: SC
authors.lastname: Eo
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749 Korea.
authors.forename: Jobi Kodiyan
authors.initials: JK
authors.lastname: Varghese
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon 443-749 Korea.
authors.forename: Bun Yeoul
authors.initials: BY
authors.lastname: Lee
keywords: CO2 chemistry; carbon dioxide; cobalt complex; phthalic anhydride; propylene oxide; terpolymerization