Microenvironmental and conformational structure of triblock copolymers in aqueous solution by H-1 an C-13 NMR spectroscopy
文献类型：期刊论文
| 作者 | Ma, J; Guo, C; Tang, Y; Wang, J; Zheng, L; Liang, X; Chen, S; Liu, H |
| 刊名 | JOURNAL OF COLLOID AND INTERFACE SCIENCE
 |
| 出版日期 | 2006-07-15 |
| 卷号 | 299期号:2页码:953-961 |
| 关键词 | Peo-ppo-peo Triblock Copolymer Microenvironnient Conformation Nmr |
| ISSN号 | 0021-9797 |
| DOI | 10.1016/j.jcis.2006.02.021 |
| 英文摘要 | H-1 and C-13 nuclear magnetic resonance (NMR) spectra of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers in D2O solutions have been systematically investigated. The detailed assignments of various H-1 and C-13 NMR signals are presented. The hyperfine structure of PO -CH2- protons was clearly assigned, the arising reason of this hyperfine structure was attributed to the influence of the chiral center of -CHCH3- groups and the direct coupling between the PO -CH2- and -CH3 protons. The external standard 2,2-dimethyl-2-silapentane-5-sulfonate sodium salt (DSS) was firstly applied in this system. Accurate chemical shift values referenced to the external standard DSS were obtained. H-1 NMR chemical shift of PO -CH2- and -CH3 signals shows a larger decrease in ppm values than that of EO -CH2- signal with the increase of PPO/PEO ratio or temperature indicating that PO segments exist in a more hydrophobic microenvironment. A new resonance signal assigned to the PO -CH2- protons appeared when the temperature is above the CMT, which is attributed to the breakdown of the intra-molecular (C-H)O-... hydrogen bond between the PO -CH2- protons and the ester oxygens. The breakdown of this intra-molecular hydrogen bond may result in a decrease of gauche conformers of the PPO chain. The increase of C-13 NMR chemical shift of block copolymers validates this conformational change assumption. It can be inferred that the amount of gauche conformers decreases whereas that of trans conformers increases in both PO and EO chains when elevating the PPO/PEO ratio or temperature. The observed C-13 NMR chemical shifts of PO segments show a bigger increase than those of EO segments, supporting the formation of a nonpolar microenvironment around PO segments. (c) 2006 Elsevier Inc. All rights reserved. |
| 语种 | 英语 |
| WOS记录号 | WOS:000238294800059 |
| 出版者 | ACADEMIC PRESS INC ELSEVIER SCIENCE |
| 源URL | [http://ir.iccas.ac.cn/handle/121111/59621]  |
| 专题 | 中国科学院化学研究所 |
| 通讯作者 | Guo, C |
| 作者单位 | 1.Chinese Acad Sci, Grad Sch, Inst Proc Engn, State Key Lab Biochem Engn,Lab Separat Sci & Engn, Beijing 100080, Peoples R China 2.Chinese Acad Sci, Inst Chem, Beijing 100080, Peoples R China |
| 推荐引用方式 GB/T 7714 | Ma, J,Guo, C,Tang, Y,et al. Microenvironmental and conformational structure of triblock copolymers in aqueous solution by H-1 an C-13 NMR spectroscopy[J]. JOURNAL OF COLLOID AND INTERFACE SCIENCE,2006,299(2):953-961. |
| APA | Ma, J.,Guo, C.,Tang, Y.,Wang, J.,Zheng, L.,...&Liu, H.(2006).Microenvironmental and conformational structure of triblock copolymers in aqueous solution by H-1 an C-13 NMR spectroscopy.JOURNAL OF COLLOID AND INTERFACE SCIENCE,299(2),953-961. |
| MLA | Ma, J,et al."Microenvironmental and conformational structure of triblock copolymers in aqueous solution by H-1 an C-13 NMR spectroscopy".JOURNAL OF COLLOID AND INTERFACE SCIENCE 299.2(2006):953-961. |
入库方式： OAI收割
来源：化学研究所
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