| abstract |
The present invention provides a block copolymer comprising at least one segment having an acid group and at least one segment substantially free from an acid group, wherein the segment having an acid group comprises a repeating unit which is a substituted repeating unit represented in the formula (1) with an acid group, n —(Ar 1 —X 1 —Ar 2 —X 2 )— (1), n and in the formula(1), X 1 and X 2 being each independently —O— or —S—, Ar 1 and Ar 2 being each independently an aromatic group selected from the groups represented by the following formulae (2) to (4). |