A method for making selectively hydrogenated block copolymers of vinyl aromatic hydrocarbons and conjugated dienes

摘要

Disclosed is a method for making selectively hydrogenated block copolymers of vinyl aromatic hydrocarbons and conjugated dienes comprising: a) anionically polymerizing vinyl aromatic hydrocarbons and conjugated dienes to produce block copolymers with living chain ends; b) terminating the living chain ends, to produce a terminated block copolymer, with a member from the group consisting of an alcohol, hydrogen, and mixtures thereof, to prepare a terminated block copolymer; and c) contacting the terminated block copolymers with hydrogen at a temperature of from 20 to 175 DEG C in the presence of a catalyst prepared by combining a cobalt carboxylate with an aluminum alkyl, wherein: (i) if the polymer is terminated with an alcohol and the alcohol is a linear alcohol, the linear alcohol is used to terminate the living chain ends in an amount such that the alcohol: living chain end molar ratio is from 0.05 to 1.2; (ii) if the polymer is terminated with an alcohol and the alcohol is a branched alcohol, the branched alcohol is used to terminate the living chain ends in an amount such that the alcohol: living chain end molar ration is from 0.05 to about 3.0; an (iii) if the polymer is terminated with an alcohol and the alcohol is a mixture of a linear alcohol and a branched alcohol, the linear alcohol is used to terminate the living chain ends in an amount such that the linear alcohol: living chain end molar ration is from 0.05 to 1.2.