Steric hindrance of the amine strongly affected the formation of the dominant 1,2-addition product from the anionic polymerization of 1,3-cyclohexadiene (1,3-CHD) initiated by the alkyllithium (RLi)/amine system in an aromatic hydrocarbon solvent. 1,2-Cyclohexadiene (1,2-CHD)/1,4-cyclohexadiene (1,4-CHD) unit molar ratios from 85/15 to 93/7 were obtained using an RLi/N,N,N',N'-tetramethylethylene-diamine (TMEDA) system in toluene. The C-Li bonds of poly(1,3-cyclohexadienyl)lithium (PCHDLi)/TMEDA complex in toluene appeared to be strongly polarized with small steric hindrance. Intermolecular forces contributing to the aggregation were strong for high-molecular-weight poly(1,3-cyclohexadiene) (PCHD) consisting of almost all 1,2-CHD units. (C) 2008 Wiley Periodicals, Inc.