Solvation Structure of Poly(ethylene glycol) in Ionic Liquids Studied by High-energy X-ray Diffraction and Molecular Dynamics Simulations

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• 作者：Hanako Asai ; Kenta Fujii ; Kengo Nishi ; Takamasa Sakai ; Koji Ohara ; Yasuhiro Umebayashi ; Mitsuhiro Shibayama
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：March 26, 2013
• 年：2013
• 卷：46
• 期：6
• 页码：2369-2375
• 全文大小：362K
• 年卷期：v.46,no.6(March 26, 2013)
• ISSN：1520-5835

文摘

Solvation structures of poly(ethylene glycol) (PEG) in 1-ethyl-3-methylimidazolium-based ionic liquids solution were studied by using high-energy X-ray diffraction (HEXRD) and molecular dynamics (MD) simulation in terms of dependences on the anion-type for ILs, molecular weight (M_w), concentration and shape (linear or tetra-armed) for PEG. It was found from HEXRD experiment that there is no M_w and shape dependences for PEG in 1-ethyl-3-methylimidazolium bis(trifluoromethansulfonyl)amide, [C₂mIm⁺][TFSA^{鈥?/sup>] solution, implying that the local structure (r < 15 脜) is not influenced by M_w and shape of PEG. From the HEXRD results with the aid of MD simulations, it was found that C₂mIm cation preferentially solvates to PEG in all the ILs, and TFSA is distributed randomly with van der Waals and weak electrostatic interactions. The atom鈥揳tom pair correlation and space distribution functions evaluated from the MD simulations revealed that hydrogen bonding interactions are formed between C2 carbon within the imidazolium ring and O (PEG), which is essentially different from C4 carbon鈥揙 and C5 carbon鈥揙 interactions. Finally, we discussed the relationship between the obtained microscopic solvation structures and the macroscopic properties of PEG-based gel (swelling ratio and 蠂 parameters).}