Dramatic solvent effects on ring-opening metathesis polymerization of cycloalkenes

A series of metathesis polymers and copolymers have been formed and their s tructures were analysed by C-13 NMR spectroscopy. Noble metal and non-noble metal salt catalysts are distinguished by their behaviour in various solve nts. Thus, in phenolic solvents, the former class produce alternating copol ymers from cyclopentene and norbornene, while the latter are unaffected and produce random copolymers. In contrast, ether solvents have the effect of markedly increasing the cis content of polymers from the latter catalysts w hile the former are unaffected. The tacticity of various polymers are correlated through their hydrogenated derivatives and found to depend on the type of monomer as well as the cata lysts. (C) 2000 Elsevier Science B.V. All rights reserved.