Block polymer preparation

Claim 1

A process of block copolymerization comprising (a) polymerizing under polymerization condition employing a hydrocarbylmonoalkali metal-based initiator at least one first polymerizable monomer until substantial completion of conversion, thereby preparing a block polymer containing a polymer-alkali metal moiety on the end thereof, (b) coupling the resulting block polymer from said step (a) with a coupling agent containing at least two reactive groups capable of reacting with said polymer-alkali metal moiety of said block polymer without terminating the activity thereof, (c) adding to the reaction mixture resulting from said coupling step (b) without termination thereof at least one second polymerizable monomer differing from said first polymerizable monomer and continuing said polymerization under polymerization conditions, until substantial completion of conversion, wherein each said polymerizable monomer is a polymerizable conjugated diene or a polymerizable monovinyl-substituted aromatic compound, wherein said hydrocarbylmonoalkali metal-based initiator is employed in a range of about 0.25 to 100 mhm, gram millimoles per 100 grams of total monomers employed, and said alkali metal is selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and wherein said coupling agent is ##EQU5## wherein R' is hydrogen or an alkyl radical of up to 4 carbon atoms, R" is a monovalent hydrocarbyl radical of up to 12 carbon atoms, n is an integer of 2-4 inclusive, p is 0 or an integer of 1-4 inclusive, such that n + p = the valence of Q, wherein Q is silicon, ton, or phosphorus.