Block copolymers and method for making same

A functionalized, selectively hydrogenated block copolymer having the general configuration A-B, A-B-A, (A-B)n, (A-B-A)n, (A-B-A)nX, (A-B)nX or mixtures thereof, which has been grafted with an acid compound or its derivative, where n is an integer from 2 to about 30, and X is a coupling agent residue and wherein:

• a. prior to hydrogenation each A block is a mono alkenyl arene polymer block and each B block is a controlled distribution copolymer block of at least one conjugated diene and at least one mono alkenyl arene;
• b. subsequent to hydrogenation about 0–10% of the arene double bonds have been reduced, and at least about 90% of the conjugated diene double bonds have been reduced;
• c. each A block having a number average molecular weight between about 3,000 and about 60,000 and each B block having a number average molecular weight between about 30,000 and 300,000;
• d. each B block comprises terminal regions adjacent to the A blocks that are rich in conjugated diene units and one or more regions not adjacent to the A blocks that are rich in mono alkenyl arene units;
• e. the total amount of mono alkenyl arene in the hydrogenated block copolymer is about 20 percent weight to about 80 percent weight;
• f. the weight percent of mono alkenyl arene in each B block is between about 10 percent and about 75 percent;
• and
• g. the styrene blockiness index of the B block is less than about 40 percent.