Anionic Graft Copolymers. I. Vinylaromatic Grafts on Polydienes

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Abstract
Lithiated polydienes were readily prepared by direct metalation of the diene polymers with sec-butyllithium and tetramethylethylenediamine in cyclohexane at room temperature. Reaction of the polylithiodienes with styrene or a-methylstyrene formed graft copolymers. Poly-1, 4-butadiene, poly-1, 2-butadiene, cis-poly-1, 4-butadiene, and polyisoprene were the substrates lithiated. The extent of metalation was much greater than previously reported metalations with n-butyllithium and terramethylethylenediamine. The grafting efficiencies, determined by acetone extraction and gel permeation chromatography, were greater than 95%. The physical properties of the graft copolymers are compared as a function of molecular weight, graft site level, and composition. At certain molecular weights, graft site level, and compositions, elastomers are formed without vulcanization. Their properties are comparable to SBS rubber and offer higher melt flow as an advantage.