Anionic polymerization initiators for preparing branched diene rubbers

Novel solid supported anionic polymerization initiators that are multiply metalated with Group IA alkali metal atoms are provided and employed to produce extremely high molecular weight branched diene polymers. The initiators are prepared by metalating a particle comprising a thermoplastic polymer or a cured elastomer in the presence of a polar coordinator. The polymers obtained by anionic polymerization employing the initiators are multiply branched, with a polymer chain covalently attached to the particle at virtually every metalation site. The macro-branched polymers exhibit desirable properties, such as an extremely high molecular weight, a controlled molecular weight distribution, Tg and vinyl content, and the ability to readily absorb hydrocarbon solvents and oils. The polymers are easily compounded to form vulcanizable elastomeric compounds and articles that have excellent resistance to wear and tear and exhibit reduced hysteresis properties.