title: Alternating copolymerization of carbon dioxide and cyclohexene oxide catalyzed by salen CoIII(acetate) complexes.
abstract: A series of CoIIIcarboxylate based uponN,N,O,O-tetradentate Schiff base ligand framework have been prepared. X-ray diffraction analysis confirms that these Schiff base CoIIIcarboxylate are all monomeric species with a six-coordinated central Co in their solid structures. The activities and polycarbonate selectivity of these complexes toward the copolymerization of epoxide (cyclohexene oxide and propylene oxide) and carbon dioxide have been investigated in the presence of bis(triphenylphosphine)iminium chloride. Copolymerization experiments indicate that [bis(α-methyl-3,5-di-tertbutyl-salicylaldehyde) ethylenediiminato] CoIIIOOCH3exhibits the highest activity and polycarbonate selectivity among these CoIIIcarboxylate. The resultant copolymer contained almost 100 % carbonate linkages with the molecular weight up to 71.8 kg mol-1as well as narrow polymer dispersity index (polymer dispersity index = 1.5). The substituents and the mode of the bridging part between the two nitrogen atoms both exert significant influences upon the progress of the copolymerizations, influencing both the polycarbonate selectivity and the rate of copolymerization.
authors: College of Chemistry & Pharmacy, Qingdao Agricultural University, Qingdao, 266109 China.
authors: Yongsheng
authors: Y
authors: Niu
authors: Hongchun
authors: H
authors: Li
keywords: Biodegradable; Carbon dioxide; Copolymerization; Poly(cyclohexene oxide); Polycarbonates
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