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.

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 T_c, T_m은 낮아졌고, 결정화 별열량, 용융 흡열량이 감소하였다. PEO-PLLA 공중합체에서 PLLA의 T_c는 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, T_g가 관찰되었다. P대-P(DLLA/GA)도 마찬가지로 냉각시에 PEO의 결정이 형성되지 않았고, 가열곡선에서 PEO 블록의 결정화 발열량과 용융 흡열량은 매우 감소되었다.

Keywords: poly(ethylene oxide)-b-poly(L-lactic acid) diblock copolymers; biodergradable polymer; thermal properties; stereo-regularity