Two‐stage polymerization of styrene in tetrahydrofuran with Na‐naphthalene

A two stage process for the anionic polymerization of styrene in THF is described. Initiation by Na‐naphthalene is carried out at room temperature with a small amount of styrene, adding the rest of the monomer by slow distillation at −78°C. The present technique yields relatively homogeneous product of predictable molecular weight. The agreement between measured molecular weights and the ones calculated from the polymerization mechanism by the relation M̄nk = 2M/[Ī] is within 10%. From fractionation, M̄w/M̄n ratios are determined to be < 1.1 for all samples.