Homo‐ and hetero‐stereocomplexes of substituted poly(lactide)s as promising biodegradable crystallization‐accelerating agents of poly( L ‐lactide)

Accelerated crystallization of poly( L ‐lactide) (PLLA) homo‐crystallites occurred in the presence of poly( L ‐2‐hydroxybutyrate) [P( L ‐2HB)], poly( D ‐2‐hydroxybutyrate) [P(D‐2HB)], and the mixture of P(L‐2HB) and P(D‐2HB) [P(L‐2HB)/P(D‐2HB)]. The accelerating effect of incorporated polymers decreased in the following order: P(L‐2HB)/P(D‐2HB) > P(D‐2HB) > P(L‐2HB) > none, for heating and isothermal crystallization for T c of 130 and 135°C and P(D‐2HB) > P(L‐2HB)/P(D‐2HB) > none > P(L‐2HB), for cooling. The P(L‐2HB)/P(D‐2HB) homo‐stereocomplex (HMSC) crystallites, P(D‐2HB)/PLLA hetero‐stereocomplex (HTSC) crystallites, and P(L‐2HB) or P(D‐2HB) homo‐crystallites are found to be promising biodegradable nucleating agents for PLLA homo‐crystallization. The P(L‐2HB)/P(D‐2HB) HMSC crystallites are most effective during isothermal crystallization and nonisothermal crystallization with heating, whereas the P(D‐2HB)/PLLA HTSC crystallites are most effective during nonisothermal crystallization with cooling from the melt. In addition to the nucleating effect, the plasticizing effect of free P(2HB) chains increases both G and the PLLA spherulite number per unit mass. These effects result in accelerated crystallization of PLLA homo‐crystallites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.