순차적 음이온 및 개환중합반응을 통한 폴리스티렌-폴리에틸렌옥사이드-폴리락티드 블록공중합체의 합성

송걸; 조병기; Jie Song; Byoung-Ki Cho

Polymer(Korea), Vol.33, No.5, 458-462, September, 2009

Synthesis of Polystyrene-b-Poly(ethylene oxide)-b-Polylactide Copolymers via Sequential Anionic and Ring-Opening Polymerizations

송걸, 조병기^†

단국대학교 화학과, 나노센서 바이오텍연구소, 광에너지소재연구센터

Jie Song, and Byoung-Ki Cho^†

Department of Chemistry, Institute of Nanosensor and Biotechnoloty, andCenter for Photofunctional Energy Materials, Dankook University, Jukjean-dong, Suji-gu, Yongin-si, Gyeonggi-do 448-701, Korea

E-mail:

초록

본 연구에서는 순차적 음이온 및 개환중합반응을 통해 ABC 형태의 폴리스티렌-폴리에틸렌옥사이드-폴리락티드 블록공중합체를 성공적으로 합성하였다. 우선, 첫번째 블록인 폴리스티렌을 합성하기 위해서, 사이클로헥산 용매에서 스티렌/이차-부틸리튬을 각각 단량체/개시제로 사용하여 음이온중합(anionic polymerization)을 수행하였고, 이후 고분자 말단을 수산기로 전환시키기 위해, 에틸렌옥사이드를 첨가하였다. 다음 단계로, 포타슘 나프탈레나이드(potassium naphthalenide)를 이용하여 폴리스티렌 말단 수산기의 수소를 제거하여, 거대개시제인 PS-O^(-)K^(+)를 제조하였다. 준비된 거대 개시제에 정량된 에틸렌옥사이드를 첨가하여, 음이온중합을 수행하였다. 폴리락티드 블록을 도입시키는 개환중합의 경우, THF 용매에서 트리에틸알루미늄(triethylaluminum)/피리딘(pyridine)시스템을 이용하여 PS-b-PEO-AlEt2 형태의 거대개시제를 형성한 후, 90 ℃에서 중합을 수행하였다. 합성된 블록공중합체를 수소핵자기공명법 및 겔침투크로마토그래피 방법을 통해 조사한 결과, 잘 정의된 분자량 및 낮은 분자량 분포를 나타냄을 확인할 수 있었다.

We have synthesized ABC linear triblock copolymers, i.e., polystyrene-b-poly(ethylene oxide)-b-polylactide, via sequential anionic and ring-opening polymerizations. In the first anionic polymerization step, styrene was polymerized in cyclohexane using sec-butyllithium as the initiator. Poly (styryl)lithium was hydroxylated by the addition of ethylene oxide, and the subsequent protonation with methanolic HCl. In the second anionic polymerization step, potassium naphthalenide was used to deprotonate the hydroxyl group of the PS to generate the macroinitiator of PS-O^(-)K^(+). Polymerization of ethylene oxide was performed in THF and terminated with methanolic HCl. In the ring-opening polymerization step, the PS-b-PEO-O-AlEt2 macroinitiator was prepared from an AlEt3/pyridine system in THF, and the polymerization of lactide was performed at 90 ℃. The resulting block copolymers showed well-defined molecular weights and narrow molecular weight distributions as revealed by 1H-NMR spectroscopy and gel permeation chromatography (GPC).

Keywords:triblock copolymer;anionic polymerization;ring-opening polymerization

[References]

[1] Epps TH, Bailey TS, Waletzko R, Bates FS, Macromolecules, 36(8), 2873 (2003)

[2] Hadjichristidis N, Pitsikalis M, Iatrou H, Pispas S, Macromol. Rapid Commun., 24(17), 979 (2003)

[3] Cho BK, Jain A, Gruner SM, Wiesner U, Science, 305, 1598 (2004)

[4] Kishimoto K, Yoshio M, Mukai T, Yoshizawa M, Ohno H, Kato T, J. Am. Chem. Soc., 125(11), 3196 (2003)

[5] Gref R, Minamitake Y, Peracchia MT, Trubetskoy V, Torchilin V, Langer R, Science, 263(5153), 1600 (1994)

[6] Bullock SE, Kofinas P, Macromolecules, 37(5), 1783 (2004)

[7] Mahajan S, Cho BK, Allgaier A, Fetters LJ, Coates GW, Wiesner U, Macromol. Rapid Commun., 25(22), 1889 (2004)

[8] Mecerreyes D, Dubois P, Jerome R, Hedrick JL, Hawker CJ, J. Polym. Sci. A: Polym. Chem., 37(13), 1923 (1999)

[9] Rzayev J, Hillmyer MA, Macromolecules, 38(1), 3 (2005)

[10] Allgaier J, Poppe A, Willner L, Richter D, Macromolecules, 30(6), 1582 (1997)

[11] Gohy JF, Adv. Polym. Sci., 190, 65 (2005)

[12] Vangeyte P, Jerome R, J. Polym. Sci. A: Polym. Chem., 42(5), 1132 (2004)

[13] Wang YB, Hillmyer MA, Macromolecules, 33(20), 7395 (2000)