Heterostereocomplex Crystallization and Homocrystallization From the Melt in Blends of Substituted and Unsubstituted Poly(lactide)s

Poly(L‐2‐hydroxybutyrate) [P(L‐2HB)] and poly(D‐lactide) (PDLA) in their blends were phase separated to form P(L‐2HB)‐ and PDLA‐enriched domains, and heterostereocomplex (HTSC) crystallization occurred at the interface between these domains. In the blends, HTSC crystallites were formed at crystallization temperature (Tc) = 80–160 °C, and their exclusive formation without the formation of other crystalline species was observed at Tc of 150 or 160 °C. The effects of polymer blend ratio on the types of formed crystalline species were very small due to the phase separation of the blends. The presence of a small amount of P(L‐2HB) decreased the low limit of crystallizable Tc of PDLA homocrystallites from 80 to 60 °C. The equilibrium melting temperature of HTSC crystallites was 257.6 °C. Heterostereocomplex (HTSC) crystallization of poly(L‐2‐hydroxybutyrate) and poly(D‐lactide) occurs in their blends at the interface between poly(L‐2‐hydroxybutyrate)‐enriched and poly (D‐lactide)‐enriched domains. HTSC crystallites are formed in the blends for crystallization temperature (Tc) = 80–160 °C, and exclusive formation of HTSC crystallites without formation of other crystalline species is observed for the samples crystallized at Tc of 150 or 160 °C, independent of the polymer blend ratio.