| 摘要 |
<p>A polymerization process for preparing a block copolymer characterized by the following steps carried out at a temperature below about -40 DEG C in the order recited, (1) polymerizing isobutylene in a reaction mixture including said isobutylene, a titanium halide, a mixed solvent, and an initiator compound selected from the group consisting of cumyl ester compounds and cumyl ether compounds, to form a first polymer, wherein when said temperature is from about -40 DEG C to -90 DEG C, or when the initiator compound has more than one ester or ether linkage, said reaction mixture is formed by first combining said mixed solvent, said initiator, said isobutylene, and a moisture scavenger, and then adding said titanium halide, and wherein said mixed solvent comprises a mixture of a non-halogenated hydrocarbon solvent with a halogenated hydrocarbon solvent, and (2) after polymerizing said isobutylene, adding a conjugated diene monomer of the general formula <CHEM> in which R1 is selected from a hydrocarbyl group containing from one to twelve carbon atoms, and R2, R3, and R4, are selected from hydrogen or a hydrocarbyl group containing from one to twelve carbon atoms, to said reaction mixture and polymerizing said diene to form a triblock copolymer in which said first polymer comprises a midblock, and the polymerized diene forms the endblocks of said triblock copolymer, or a multi-block copolymer in which said first polymer comprises an elastomeric segment flanked by blocks of the polymerized diene containing partially cyclized segments.</p> |
