BLOCK COPOLYMERS INCLUDING HIGH VINYL SEGMENTS
A method for the preparation of block copolymers including at least one high vinyl segment, the method comprising (i) charging into a reactor a diene monomer in a hydrocarbon solvent, a catalytically effective amount of anionic initiator, and an oligomeric oxolanyl propane, whereby the reactor is optionally cooled, to form a first batch; (ii) allowing the monomer to polymerize at a peak polymerization temperature of at least about 18° C. and less than about 60° C. to form a first block where the vinyl content is at least about 50 percent by weight; (iii) charging into the reactor a vinyl aromatic monomer, whereby the reactor is optionally heated to a temperature up to about 60° C., to form a second batch; (iv) allowing the monomer to polymerize the second batch to fully convert all monomer to form a second block; and (v) charging into the reactor a quenching agent.
1 . A method for the preparation of block copolymers including at least one high vinyl segment, the method comprising
(i) charging into a reactor 1,3-butadiene monomer in a hydrocarbon solvent, a catalytically effective amount of anionic initiator, and an oligomeric oxolanyl propane to thereby form a first batch, where the oligomeric oxolanyl propane is provided in an amount of at least 1.0 mole and less than 5 moles of oligomeric oxolanyl propane per mole of lithium associated with the anionic initiator;
(ii) allowing the monomer to polymerize, while maintaining a solids content of at least 2% and below 7%, to thereby form a first polybutadiene block having a vinyl content of at least 80%, where the peak polymerization temperature achieved during the polymerization of step (ii) is at least 18° C. and less than 46° C.;
(iii) charging into the reactor a vinyl aromatic monomer to form a second batch;
(iv) allowing the monomer of the second batch to polymerize to fully convert all monomer to thereby form a second block;
(v) dropping to a temperature below 30° C. and charging 1,3-butadiene monomer into the reactor to form a third batch;
(vi) allowing the monomer of the third batch to polymerize, while maintaining a solids content of at least 8% and below 18%, to thereby form a third block, where the third block is a second polybutadiene block, where the peak polymerization temperature achieved during the polymerization of step (vi) is at least 18° C. and less than 55° C.;
(vii) further charging into the reactor vinyl aromatic monomer to form a fourth batch;
(viii) allowing the monomer of the fourth batch to polymerize to thereby form a fourth block;
(ix) charging into the reactor a quenching agent; and
where the method produces a block copolymer having an overall vinyl content that is greater than 80%.
2 . The method of claim 1 , wherein the vinyl aromatic monomer is styrene and step (iv) forms a first polystyrene block and step (viii) forms a second polystyrene block.
3 . The method of claim 1 , wherein the hydrocarbon solvent includes hexane.
4 . The method of claim 1 , where the vinyl content of the first block is at least 85%.
5 . The method of claim 1 , where the method produces a block copolymer having an overall vinyl content that is greater than 85%.
6 . The method of claim 1 , where the where the oligomeric oxolanyl propane is provided in an amount of at least 1.0 mole and less than 2.5 moles of oligomeric oxolanyl propane per mole of lithium associated with the anionic initiator.
7 . The method of claim 1 , where the first polybutadiene block includes at least 40 and less than 160 mer units.
8 . The method of claim 1 , where the first polybutadiene block includes at least 60 and less than 120 mer units.
9 . The method of claim 6 , where the method produces a block copolymer having an overall vinyl content that is greater than 85%.
10 . The method of claim 8 , where the method produces a block copolymer having an overall vinyl content that is greater than 85%.
11 . A method for the preparation of block copolymers including at least one high vinyl segment, the method comprising
(i) charging into a reactor 1,3-butadiene monomer in hexane, a catalytically effective amount of anionic initiator comprising lithium, and an oligomeric oxolanyl propane to thereby form a first batch, where the oligomeric oxolanyl propane is provided in an amount of at least 1.0 mole and less than 2.5 moles of oligomeric oxolanyl propane per mole of lithium associated with the anionic initiator;
(ii) allowing the monomer to polymerize, while maintaining a solids content of at least 2% and below 7%, to thereby form a first polybutadiene block having a vinyl content of at least 85%, where the peak polymerization temperature achieved during the polymerization of step (ii) is at least 18° C. and less than 46° C.;
(iii) charging into the reactor styrene to form a second batch;
(iv) allowing the styrene of the second batch to polymerize to fully polymerize all styrene to thereby form a second block;
(v) dropping to a temperature below 30° C. and charging 1,3-butadiene monomer into the reactor to form a third batch;
(vi) allowing the monomer of the third batch to polymerize, while maintaining a solids content of at least 8% and below 18%, to thereby form a third block, where the third block is a second polybutadiene block, where the peak polymerization temperature achieved during the polymerization of step (vi) is at least 18° C. and less than 55° C.;
(vii) further charging into the reactor styrene to form a fourth batch;
(viii) allowing the styrene of the fourth batch to polymerize to thereby form a fourth block;
(ix) charging into the reactor a quenching agent; and
where the method produces a block copolymer having an overall vinyl content that is greater than 85%.