Effect of mixed solvents on the thermal properties of poly(L-lactic acid) (PLLA) solution and micromorphology of porous PLLA scaffolds

Abstract

The composition of the poly(L-lactic acid) (PLLA) solution has an important influence on the preparation process and microstructure of the PLLA scaffold. In this work, porous PLLA scaffolds were prepared by solvent casting/freeze-drying method. Two mixed solvent systems (1, 4-dioxane/dichloromethane, 1, 4-dioxane/trichloromethane) were used to dissolve PLLA to form a series of ternary PLLA solutions. The crystallization process and melting process of the PLLA solutions were investigated by differential scanning calorimetry (DSC). The DSC test results show that the crystallization peak temperature and the melting peak temperature of the ternary PLLA solutions strongly depend on the composition and content of the mixed solvent. PLLA solutions were cast into the gaps of the ice-based microspheres (300–380 μm) to form scaffold samples. After freezing and lyophilizing the scaffold samples, PLLA scaffolds with macroporous, microporous, and nanofiber structures can be obtained. In addition, the porosity and compressive strength of the porous PLLA scaffolds were tested.