| 학회 | 한국고분자학회 |
| 학술대회 | 2004년 가을 (10/08 ~ 10/09, 경북대학교) |
| 권호 | 29권 2호, p.501 |
| 발표분야 | 고분자 구조 및 물성 |
| 제목 | Morphology Formation of Poly(L-lactic acid) Solution via Thermally Induced Phase Separation |
| 초록 | Thermally induced phase separation (TIPS) is a versatile and simple technique for the preparation of microporous membranes.1,2 Since its development in the early 1980s, much attention has been focused on its applicability to insoluble polymers at room temperature and utility for morphology control with fewer variables. In recent years, several researchers have tried to employ TIPS process for the fabrication of scaffolds in tissue engineering.3 Morphology control plays a critical role for this application. In this study, the structure of poly(L-lactic acid) (PLLA) solutions was investigated during the thermally induced phase separation process. A series of dialkyl phthalates, with different numbers of carbon atoms in the alkyl chain, was employed as a solvent to control the interaction between the polymer and solvent. Liquid-liquid phase separation temperature and crystallization temperature were experimentally determined by optical microscopy and differential scanning calorimetry respectively to construct the phase diagram. These results were in good accordance with the calculated phase diagram. The final morphology of PLLA solutions was investigated by changing the variables of TIPS process such as solvent quality, quenching temperature, PLLA molecular weight and solution concentration. The pore sizes increased when quenching temperature and solvent quality were decreased, which allow liquid-liquid phase separation to progress further before crystallization (Fig. 1). When the polymer concentration was low and PLLA molecular weight was decreased, the rate of liquid-liquid phase separation is increased because of low viscosity and ease of diffusion, so large pores were obtained. In addition the coarsening effect was also examined. The coarsening process was observed by optical microscope and scanning electron microscopy. The coarsening effect induced by two-step quenching method is helpful to control the pore structure and size by adjusting the coarsening time and temperature. Fig. 1. SEM micrographs of cross-section for 10wt% PLLA (Mn of 46,000) in a solvent quenched to 30oC; solvent is dibutyl phthalate (a), dipentyl phthalate (b), and dihexyl phthalate (c) References 1. F. Tsai and J. M. Torkelson, Macromolecules, 23, 775 (1990). 2. S. S. Kim and D. R. Lloyd, J. Membr. Sci., 64, 13 (1991). 3. H. Okada and H. Toguchi, Crit. Rev. Ther. Drug., 12, 1 (1995). |
| 저자 | 이재성1, 김성철1, 이환광2 |
| 소속 | 1한국과학기술원 기능성고분자신소재연구센터, 2청운대 |
| 키워드 | Thermally induced phase separation; Poly(L-lactic acid); Morphology |
