화학공학소재연구정보센터
Polymer(Korea), Vol.23, No.1, 32-41, January, 1999
Poly(ethylene oxide)-Poly(lactic acid) Diblock Copolymer의 열적성질
Thermal Properties of Poly(ethylene oxide)-Poly(lactic acid) Diblock Copolymers
초록
Poly(ethylene oxide) (PEO)에 L-lactide(LA), DL-latide, glycolide(GA)를 개환 중합하여 PEO-PLLA, PEO-P(LLA/GA), PEO-P(DLLA/GA) diblock 공중합체들을 제조하였다. 시차주사 열분서기 (DSC)를 사용하여 공중합체의 열적 특성을 조사하였다. PLLA, P(LLA/GA), P(DLLA/GA) 블록들의 길이가 증가할수록 PEO 블록의 Tc, Tm은 낮아졌고, 결정화 별열량, 용융 흡열량이 감소하였다. PEO-PLLA 공중합체에서 PLLA의 Tc는 분자량의 변화에 따라 크게 변화하였다. 낮은 분자량의 PLLA는 용융 피이크가 PEO와 겹쳐졌다. PEO-P(LLA/GA)는 입체적으로 불규칙한 P(LLA/GA) 블록의 영향으로 PEO 블록의 결정화 발열 피이크가 냉각시에 나타나지 않고, 이차 가열곡선에서 나타났으며, Tg가 관찰되었다. P대-P(DLLA/GA)도 마찬가지로 냉각시에 PEO의 결정이 형성되지 않았고, 가열곡선에서 PEO 블록의 결정화 발열량과 용융 흡열량은 매우 감소되었다.
Poly(ethylene oxide)-b-poly(L-lactic acid) (PEO-PLLA), poly(ethylene oxide)-b-poly(L-lactic acid-co-glycolic acid) (PEO-P(LLA/GA)), and poly(ethylene oxide)-b-poly(DL-lactic acid-co-glycolic acid) (PEO-P(DLLA/GA)) were prepared via ring opening polymerization from poly(ethylene oxide), L- and DL-lactide, and glycolide. Their thermal properties were investigated by using DSC. As the length of PLLA, P(LLA/GA), and P(DLLS/GA) blocks increased, Tc, Tm, crystallization exotherm, and melthing endotherm of PEO blocks decreased. The Tc of PLLA block of PEO-PLLA was significantly affected by changing the molecular weight. The co-melting of PEO and PLLA occurred when the PLLA was low molecular weight. The crystallization exotherm of PEO block was not observed during cooling run of PEO-P(LLA/GA). But, thecrystallization peak and Tg of PEO blocks appeared in the second heating run due to the steric hindrance of stereo irregular P(LLA/GA) blocks. PEO-P(DLLA/GA) showed the same pattern except showing the more decreased crystallization exotherm and melthing endotherm of PEO.
  1. Schmitt EE, Polistina RA, U.S. Patent, 3,297,033 (1967)
  2. Frazza EJ, Schimitt EE, J. Biomed. Mater. Res., 1, 43 (1971) 
  3. Kulkarni RK, Pani KC, Nauman C, Leonard F, J. Biomed. Mater. Res., 5, 169 (1971)
  4. Schneider AK, U.S. Patent, 3,636,956 (1975)
  5. Gilding DK, Reed AM, Polymer, 20, 1459 (1979) 
  6. Jackanicz TM, Nash HA, Wise DL, Gregory JB, Contraception, 8, 277 (1973)
  7. Schmitt EE, Epstein MA, A. Patent, 718,150 (1971)
  8. Hollinger JO, J. Biomed. Mater. Res., 17, 71 (1983) 
  9. Kulkarni RK, Panl KC, Neuman C, Leonard F, J. Biomed. Mater. Res., 5, 169 (1971)
  10. Herold DK, Keil K, Bruns DE, Biochem. Pharmacol., 38, 73 (1989) 
  11. Richter AW, Akerblom E, Int. Arch. Allergy Appl. Immunol., 70, 124 (1983)
  12. Jeong B, Bae YH, Lee DS, Kim SW, Nature, 388(6645), 860 (1997) 
  13. Bailey FE, Koleske JV, "Poly(ethylene oxide)," Chapter IV, Academic Press, New York, 1976 (1976)
  14. Jeong B, Lee DS, Shon JI, Bae YH, Kim SW, J. Polym. Sci. A: Polym. Chem., in press
  15. Choi SW, Choi SY, Jeong B, Kim SW, Lee DS, J. Polym. Sci. A: Polym. Chem., in press
  16. Fischer EW, Sterzel HJ, Wegner G, Kolloid-Z. u.Z. Polym., 251, 980 (1973) 
  17. Grijpma DW, Pennings AJ, Macromol. Chem. Phys., 195, 1663 (1994)
  18. Rashkov I, Manolova N, Li SM, Espartero JL, Vert M, Macromolecules, 29(1), 50 (1996) 
  19. Cerrai P, Tricoli M, Lelli L, Guerra GD, Sbarbati R, Guerra D, Cascone MG, Giusti PJ, Mater. Sci. Mater. Med., 5, 308 (1994)