The crystallization behavior of the stereoblock copolymer of substituted and non-substituted poly(lactide)s, i.e., poly(D-2-hydroxybutyrate) and poly(L-lactide) chains having the opposite configurations [P(D-2HB)-b-PLLA] and the reference block copolymer of poly(D-2-hydroxybutyrate) and poly(o-lactide) chains with the identical configurations [P(D-2HB)-b-PDLA] was investigated. At the crystallizable temperature range of 60-160 degrees C, the crystallized P(D-2HB)-6-PLLA contained solely the hetero-stereo-complex crystallites as a crystalline species, without formation of poly(D-2-hydroxybutyrate) or poly (L-lactide) homo-crystallites, in contrast with their polymer blends. On the other hand, at the crystallizable temperature range of 60-140 degrees C, the crystallized P(D-2HB)-b-PDLA had only PDLA homo-crystallites as crystalline species, reflecting no co-crystallites formation between poly(D-2-hydroxybutyrate) and poly(o-lactide) chains having the same configurations. The equilibrium melting temperature of hetero-stereocomplex crystallites in P(D-2HB)-b-PLLA was 189.0 degrees C, which was higher than 171.3 degrees C of PDLA homo-crystallites in P(D-2H8)-6-PDLA. Although the final crystallinity of P(D-2HB)-6-PLIA was higher than those of P(D-2HB)-b-PDLA, the spherulite growth rate of P(D-2HB)-6-PLLA was lower. The regime analysis indicated unusual nucleation mechanism of P(D-2HB)-b-PLLA. (C) 2011 Elsevier Ltd. All rights reserved.