| abstract |
A copolymer including a repeating unit represented by Formula I: wherein: L is a divalent hydrocarbon group comprising from 1 to 12 carbon atoms; and L′ is optional and when present is represented by Formula II: wherein: Y, Y′ and Y″ if present, are independently selected from: a carboxylic acid, sulfonic acid, phosphorous acid and phosphoric acid and their corresponding salt or ester; imino, amide, nitrile, hydrogen, hydroxyl and alkyl comprising from 1 to 6 carbon atoms; and A, A′ and A″ if present, are independently selected from an arylene moiety, with the proviso one or both Y″ and A″ may not be present. |