BIODEGRADABLE BLOCK COPOLYMER

The purpose of the present invention is to provide a biodegradable block copolymer which combines high conformability with excellent degradability. The present invention provides a block copolymer which comprises a poly(alkylene glycol) block and a poly(hydroxyalkanoic acid) block, wherein the proportion by mass of the poly(alkylene glycol) block to the whole mass is 10-60%, the block copolymer having a carbon-nucleus relaxation time T1 rho regarding the carbonyl carbon atom of 20 ms or less and satisfying expression 1. chi = chi 1* chi 2>=20 (expression 1) chi 1 is the degree of crystallization of the poly(alkylene glycol) block. chi 2 is the degree of crystallization of a poly-A block, where A is a repeating unit, among the repeating units contained in the poly(hydroxyalkanoic acid) block, that is the highest in the degree of crystallization of the homopolymer made up of the same repeating units alone. 本发明的目的在于，提供具有高追随性和优异的降解性的具有生物降解性的嵌段共聚物。本发明提供嵌段共聚物，其包含聚亚烷基二醇嵌段和聚羟基烷酸嵌段，聚亚烷基二醇嵌段相对于全部质量的质量比率为10~60%，羰基碳的碳核弛豫