| 학회 | 한국고분자학회 |
| 학술대회 | 2004년 가을 (10/08 ~ 10/09, 경북대학교) |
| 권호 | 29권 2호, p.597 |
| 발표분야 | 기능성 고분자 |
| 제목 | pH-Dependent Formation of Polypseudorotaxane between Cyclodextrins and Cationic Linear Polyethylenimine |
| 초록 | Polypseudorotaxanes or polyrotaxanes useful for constructing new types of supramolecular structures have been based on nonionic polymers such as PEG, PPG, and aliphatic polyesters.1 In a view of developing stimuli-responsive polyrotaxanes, ionic polymers may be a good building block since the inclusion complexation can be controlled via external stimuli, more specifically pH. In this study, a series of linear polyethylenimines (LPEIs) with various molecular weights was synthesized and examined for pH-dependent polypseudorotaxane formation with α- or γ-cyclodextrins (α-, γ-CDs). The polypseudorotaxane formation was significantly dependent on the pH of the aqueous media. The maximum yield of the recovered polypseudorotaxane precipitates was observed at pH 11.0, whereas no complexation was observed in the pH range below 8.0 due to the protonation of secondary amine groups in LPEI backbones. This suggests that the ionization of the secondary amine groups leads to dethreading of CD molecules because PEI chains with cationic nature disfavor the hydrophobic cavities of CDs.2 The solid-state 13C CP/MAS NMR and X-ray diffraction measurements verified the successful formation of crystalline polypseudorotaxanes through the inclusion complexation. In addition, 1H NMR analysis showed that LPEI formed a 2:1 inclusion complex with α-CD ([EI]:[α-CD] = 2:1) and a 4:1 complex with γ-CD ([EI]:[γ-CD] = 4:1) as reported in poly(ethylene glycol)-based polypseudorotaxane system. Such unique pH-controllable polypseudorotaxane formation may be useful in designing many building blocks for stimuli-responsive polyrotaxanes. 참고문헌 1. A. Harada, and M. Kamachi, Nature, 370, 126 (1994). 2. H. S. Choi, S. C. Lee, T. Ooya, S. Sasaki, M. Kurisawa, H. Uyama, and N. Yui, Macromolecules (in press). |
| 저자 | 이상천1, 김경자1, 최학수2, Tooru Ooya2, Nobuhiko Yui2 |
| 소속 | 1요업(세라믹)기술원 생체재료팀, 2Japan Advanced Institute of Science and Technology School of Materials Science |
| 키워드 | cyclodextrin; PEG; polyrotaxanes; stimuli-sensitive |
