title: Relationship between mesoscale dynamics and shear relaxation of ionic liquids with long alkyl chain.
abstract: The shear relaxation spectra of three imidazolium-based ionic liquids, 1-methyl-3-octylimidazolium chloride ([C(8)mim][Cl]), 1-methyl-3-octylimidazolium hexafluorophosphate ([C(8)mim][PF(6)]), and 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C(12)mim][TFSA]) were measured and compared with the intermediate scattering functions determined with neutron spin echo (NSE) spectroscopy. The shear relaxation is slower than that predicted from the relaxation of the main peak of the structure factor that is common to other molecular liquids, whereas it is faster than that from the relaxation of the pre-peak, that corresponds to the correlation length of about 10 nm specific to ionic liquids with an intermediately long alkyl chain. The role of the pre-peak structure in the mechanism of shear viscosity of ionic liquids is discussed based on the comparison between NSE and shear relaxations.
authors.affiliation: Department of Molecular Design and Engineering, Graduate School of Engineering, Furo-cho B2-3 (611), Chikusa, Nagoya, Aichi 464-8603, Japan. tyama@nuce.nagoya-u.ac.jp
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Mikawa
authors.forename: Shinobu
authors.initials: S
authors.lastname: Koda
authors.forename: Kenta
authors.initials: K
authors.lastname: Fujii
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endo
authors.forename: Mitsuhoro
authors.initials: M
authors.lastname: Shibayama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hamano
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Umebayashi
mesh_terms: D052578:Ionic Liquids / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D009502:Neutrons; D013057:Spectrum Analysis; D014783:Viscosity
chemical_list: D052578:Ionic Liquids