Poly(lactic acid) is widely known as the biodegradable and biocompatible material. It is used to the tissue engineering and drug delivery system as porous scaffolds. Thermally induced phase separation (TIPS) is a simple and ideal method for the fabrication of scaffolds. Nevertheless the difficulty in the morphology control is limited its application. In this study, TIPS in poly(lactic acid)/dialkyl phthalate system was investigated. A series of dialkyl phthalates, with different number of carbon atoms in the alkyl chain, was used to control the solvent power. The phase diagram was constructed to understand the change of the phase transition temperature with the change of the solvent power. From the numerical calculation the interaction parameter and the theta temperature were estimated. In order to investigate the competitive phase separation between the liquid-liquid phase separation and crystallization, temperature jump experiment was carried out. The factors which could influence the final morphology were examined.
