New polymerization of dienes and related monomers catalyzed by late transition metal complexes

[摘要] This article reviews recent studies on the polymerization of 1,6-heptadienes and 2-aryl- and 2-alkoxy-1-methylenecyclopropanes catalyzed by Co, Fe, and Pd complexes. Co and Fe complexes with bis(imino)pyridine ligands catalyze the cyclopolymerization of 1,6-heptadiene in the presence of MMAO to produce the polymer, which contains five-membered rings in the monomer units. The polymers with cis- or trans-five-membered rings are obtained selectively, depending on the complex used in the polymerization. The catalyst, prepared from the Co complex having a bis(imino)pyridine ligand and MMAO, promotes the polymerization of 2-aryl-1-methylenecyclopropanes without ring-opening. The reaction under ethylene atmosphere produces alternating copolymer of the two monomers to yield the polymers composed of the C4 repeating unit with a 1,1-cyclopropanediyl group. The alternating copolymer of ethylene and 7-methylenebicyclo[4.1.0]heptane undergoes thermal rearrangement to afford the polymer with C C double bond in main chain. A radical pathway is proposed. Dinuclear pi-allylpalladium complexes with bridging Cl ligands initiate living polymerization of 2-alkoxy-1-methylenecyclopropanes, which accompanies ring-opening of the monomer, to afford the polymers composed of the C-3 repeating units having alkoxy and vinylidene groups. A cyclic dinuclear pi-allylpalladium complex reacts with 2-alkoxy-1-methylenecyclopropane in the presence of pyridine to produce the living polymer with macrocyclic structures. Block copolymerization of the two monomers that contain OR or O(CH2CH2O)R as the substituents on the three-membered ring, results in the polymers with hydrophobic and hydrophilic segments. (C) 2008 Elsevier Ltd. All rights reserved.

[发布日期] 2008-10-30

[关键词] Ring-opening polymerization;Cyclopolymerization;Diene;Cobalt;Palladium