Copolymerization of Ethylene with Methylenecyclopropanes Promoted by Cobalt and Nickel Complexes
作者:Daisuke Takeuchi、Kouhei Anada、Kohtaro Osakada
DOI:10.1246/bcsj.78.1868
日期:2005.10
The cobalt and nickel complexes promote addition polymerization of substituted methylenecyclopropanes as well as their copolymerization with ethylene to afford the polymers that contain three-membered rings. The homopolymerization of 2-aryl-1-methylenecyclopropane catalyzed by [CoCl2(L)]–MMAO (L = bis(1-iminoalkyl)pyridine ligand) at −40 °C produces the polymers with a narrow molecular weight distribution. The copolymer of ethylene and 2-aryl-1-methylenecyclopropane is also obtained by using the same catalyst. The ratio of the two monomer units varies in the range from 0 to 0.5 depending on the concentration of ethylene and 2-aryl-1-methylenecyclopropane. 13C1H} NMR spectrum of the alternating copolymer exhibits a single sharp signal for each carbon of the repeating units. Ethylene and 7-methylenebicyclo[4.1.0]heptane also undergo alternating copolymerization to produce the polymer having the C4 repeating unit containing a bicyclic group. Heating the polymer at 130 °C causes ring-opening isomerization to afford the polymer having a C=C double bond in the main chain. Mixtures of [Ni(π-C3H5)Br]2, a diimine ligand, and cocatalysts such as NaBARF and Et2AlCl, initiate the copolymerization of ethylene with 2-aryl-1-methylenecyclopropane to give a random copolymer with a low molecular weight (Mn = 1000–2000).
Alternating Copolymerization of Ethylene with 7-Methylenebicyclo[4.1.0]heptane Promoted by the Cobalt Complex. Highly Regulated Structure and Thermal Rearrangement of the Obtained Copolymer