Self-Assembly of Stereocomplex-Type Poly(lactic acid)

Enantiomeric poly(lactide)s were assembled by casting solutions of poly(L-lactic acid) and poly(D-lactic acid) with different drying process and annealing procedures. Crystallization in these films was studied by differential scanning calorimetric study and wide-angle X-ray diffraction. Stereocomplex crystallization occurred more predominantly than homo crystal during casting and annealing. Atomic force microscopic observation showed solution-grown single crystal like structure on the substrate surface. We found that stereocomplex crystal formation was enhanced via homo crystal formation. On the basis of these findings, a mechanism is proposed for the crystallization of enantiomeric poly(lactic acid)s when they are cast from dilute solution.