ABA block copolymer including lactic acid units

Abstract

Disclosed herein is an ABA type block copolymer including a repeating unit derived from lactic acid that is excellent in physical properties, such as toughness. The ABA type block copolymer includes a polymer block A including a repeating unit derived from lactic acid and a polymer block B including a repeating unit represented by a formula [I] linked in an order of A-B-A. In the following formula [I], R1 represents a hydrogen atom, an unsubstituted or substituted alkyl group, or an unsubstituted or substituted aryl group, R2 and R3 each independently represent a hydrogen atom, an unsubstituted or substituted alkyl group, or an unsubstituted or substituted aryl group, and n represents an integer of 1 to 10. X represents —S—, —SO— or —SO2—, and R4 represents an unsubstituted or substituted alkyl group, or an unsubstituted or substituted aryl group.

Dependencies are inferred from the claim text.