Polar Modifier Systems for High Vinyl Block Copolymerization

A polar modifier system for making block copolymers of vinyl aromatic monomers and conjugated diene monomers by anionic polymerization using an organolithium initiator, comprising:

• (a) one or more of the chemicals selected from the group consisting of ditetrahydrofurfurylpropane, ethyltetrahydrofurfuryl ether, N,N,N′,N′-tetramethyl ethylenediamine and tetrahydrofurfuryl-N,N-dimethylamine;
• (b) bis[2-(N,N-dimethylamino)ethyl] ether;
• and
• (c) a sodium alkoxide compound.

A block copolymer having the formula:

• (S—B)n-S, (B—S)n-B, or (S—B)n,
• wherein S is a vinyl aromatic polymer block,
• wherein S content in the block copolymer is from 10 to 40 wt %,
• wherein randomized vinyl aromatic repeat unit content is less than 15 wt % based on total vinyl aromatic content,
• wherein B is a conjugated diene polymer block,
• wherein the B block has a vinyl content of more than 85 mol % on a conjugated diene repeat unit basis, including 1,2-vinyl, 3,4-vinyl and vinylcyclopentane (VCP) repeat units,
• wherein n is a value from 1 to 5, and
• wherein the GPC peak molecular weight Mp of the block copolymer relative to polystyrene standards is from 50 to 300 kg/mol.

A block copolymer having the formula:

• ((S—B—)m)n-X, or ((B—S)m)n-X,
• wherein S is a vinyl aromatic polymer block,
• wherein S content in the block copolymer is from 10 to 40 wt %,
• wherein randomized vinyl aromatic repeat unit content is less than 15 wt % based on total vinyl aromatic content,
• wherein B is a conjugated diene polymer block,
• wherein the B block has a vinyl content of more than 85 mol % on a conjugated diene repeat unit basis, including 1,2-vinyl, 3,4-vinyl and vinylcyclopentane (VCP) repeat units,
• wherein m is a value from 1 to 3,
• wherein n is a value from 2 to 4,
• wherein X is the residue of a coupling agent,
• wherein the GPC peak molecular weight Mp of the block copolymer relative to polystyrene standards is from 120 to 480 kg/mol, and
• wherein the block copolymer has more than 15 wt % of di-block un-coupled copolymer having the formula S—B.

A block copolymer having the formula:

• S—B—S-f or ((S—B)n-)-f,
• wherein S is a vinyl aromatic polymer block,
• wherein S content in the block copolymer is from 10 to 40 wt %,
• wherein randomized vinyl aromatic repeat unit content is less than 15 wt % based on total vinyl aromatic content,
• wherein B is a conjugated diene polymer block,
• wherein the B block has a vinyl content of more than 85 mol % on a conjugated diene repeat unit basis, including 1,2-vinyl, 3,4-vinyl and vinylcyclopentane (VCP) repeat units,
• wherein f is an end group with an —OH or an —NH—R moiety, and
• wherein the GPC peak molecular weight Mp of the block copolymer relative to polystyrene standards is from 50 to 300 kg/mol.