Stereocomplex Formation in Enantiomeric Polylactides by Melting Recrystallization of Homocrystals: Crystallization Kinetics and Crystal Morphology

Abstract

Crystallization kinetics and crystal morphology of polylactide stereocomplex through melting recrystallization of homocrystals was investigated in detail. Small homocrystals with the α′-form and large ones with the α-form were produced by annealing of amorphous 1:1 poly(l-lactide)/poly(d-lactide) blends at 80 and 120 °C, respectively. Small homocrystals with the α′-form were more favorable than large ones with the α-form for stereocomplex formation through melting recrystallization. Moreover, rod-like stereocomplex crystals were produced from melting of small homocrystals with the α′-form at the adopted crystallization temperatures. In contrast, plate-like or spherulitic stereocomplex crystals were generated by melting of large homocrystals with the α-form. The difference in the crystal morphology of sterecomplex was correlated with the variation of nucleation density regarding annealing and crystallization temperatures.