Enantiomeric substituted polylactides, poly(L-2-hydroxybutyrate) [P(L-2HB)] and poly(D-2-hydroxybutyrate) [P(D-2HB)] with different weight-average molecular weights (M-w = 1.8 x 10(3)-4.1 x 10(4) g mol(-1)) were synthesized by acid-catalyzed polycondensation. The effects of molecular weights of P(L-2HB) and P(D-2HB) and crystallization conditions on stereocomplex (SC) crystallization and homo-crystallization of neat P(L-2HB), neat P(D-2HB), and their equimolar blends were investigated by means of differential scanning calorimetry and wide-angle X-ray scattering. Only SC crystallites were formed during solution-crystallization of the blends without the formation of homo-crystallites, irrespective of average M-w. SC crystallites were only crystalline species formed during melt-crystallization of the blends, in the crystallization temperature (T-c) range of 55-160 degrees C (except at 70 degrees C). At T-c = 70 degrees C, in addition to SC crystallites, a significant amount of homo-crystallites were formed for average M-w exceeding 2.7 x 10(4) g mol(-1), and equal amounts of SC crystallites and homo-crystallites were formed for average M-w exceeding 3.2 x 10(4) g mol(-1). However, a critical average M-w above which predominant homo-crystallization and no SC crystallization occur was not observed. The equilibrium melting temperature of SC crystallites obtained by the Hoffman-Weeks procedure was 239.1 degrees C, which was lower than the highest value (279 degrees C) reported for polylactide SC crystallites. In solution-crystallization of the neat P(L-2HB) and P(D-2HB), a new type of homo-crystallites were formed for M-w below 1 x 10(4) g mol(-1) and the normal type of homo-crystallites were formed for M-w above 1 x 10(4) g mol(-1). In contrast, melt-crystallization of the neat P(L-2HB) and P(D-2HB) generated the new and the normal type homo-crystallites for M-w = 9 x 10(3)-1 x 1(0)4 g mol(-1) and M-w above 9 x 10(3) g respectively. (C) 2012 Elsevier Ltd. All rights reserved.