| abstract |
A method for preparing a diene polymer or copolymer having increased amounts of 1,2-microstructure is provided. The method involves polymerizing a diene monomer or mixture of a diene monomer and a vinyl aromatic hydrocarbon monomer in a hydrocarbon solvent in the presence of a catalytically effective amount of a catalyst composition comprising: (a) an organolithium initiator and (b) an oxolanyl cyclic acetal having the structural formula: ##STR1## wherein R is selected from the group consisting of hydrogen and alkyl groups containing from 1 to 4 carbon atoms and X is 0 or 1. |