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Addition of polar modifiers to alkyllithium‐initiated homopolymerizations of butadiene causes substantial changes in the microstructure of the polymers produced. These changes are shown to depend not only on the concentration of modifier, but also on the polymerization temperature. The combined effects of modifier concentration and reaction temperature have been considered, and a method is presented for quickly determining the proper conditions for preparation of a polybutadiene of any 1,2‐microstructure within a range of 10–80%. It is also shown that in anionic polar‐modified copolymerizations of butadiene–styrene, the reaction temperature is again critical. Within a certain concentration range of modifier, the temperature will influence the rate of styrene incorporation or the randomness of styrene units in the resulting copolymers.

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Polybutadiene was successfully metalated by use of tert‐butyllithium activated with alkoxides of Group I metals without chain degradation. The metalated polymer was grafted with styrene and 1,3‐butadiene to give novel graft copolymers of varying microstructure. This metalating system was found to be highly efficient; however, its catalyst effectiveness is less than that of organolithium‐TMEDA metalation agent.