Some results of cesium‐initiated diene polymerization and copolymerization

A study of the homogeneous polymerization of isoprene and butadiene by means of alkali aromatic complexes confirmed the influence of polarity of the medium on the microstructure of the homopolymer. Cesium napthalene in tetrahydrofuran yielded a high concentration of the 1,2‐adduct (29%) and 3,4‐adduct (43%) in polyisoprene, but a comparatively low concentration of 1,2‐structures (74.5%) in polybutadiene. Practically pure 1,2‐polybutadiene was synthesized by means of Li naphthalene. A gradual decrease in the concentration of 1,2‐polybutadiene structures was noted as the electropositivity of the alkali counterion increased. The influence of solvent, temperature, and molecular weight on the structure of polybutadiene was examined. Copolymerization of the isoprene–styrene monomer pair yielded block polymers. The determination of the torsional modulus–temperature spectrum afforded a simple method for distinguishing block from rando compolymers.