Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
根本 文也*; 古府 麻衣子; 長尾 道弘*; 大石 一城*; 高田 慎一; 鈴木 淳市*; 山田 武*; 柴田 薫; 上木 岳士*; 北沢 侑造*; et al.
Journal of Chemical Physics, 149(5), p.054502_1 - 054502_11, 2018/08
被引用回数:24 パーセンタイル:74.52(Chemistry, Physical)Alkyl-methyl-imidazolium ionic liquids CmimX (
: alkyl-carbon number, X: anion) have short-range layer structures consisting of ionic and neutral (alkylchain) domains. To investigate the temperature dependences of the interlayer, interionic group, and inter-alkylchain correlations, we have measured the neutron diffraction (ND) of C
mimPF
(
= 16, 9.5, 8). The quasielastic neutron scattering (QENS) of C16mimPF
was also measured to study the dynamics of each correlation. C16mimPF
shows a first-order transition between the liquid (L) and liquid crystalline (LC) phases at
= 394 K. C8mimPF
exhibits a glass transition at
= 200 K. C9.5mimPF
has both transitions at
= 225 K and
= 203 K. In the ND experiments, all samples exhibit three peaks corresponding to the correlations mentioned above. The widths of the interlayer peak at ca. 0.2
changed drastically at the L-LC transitions, while the interionic peaks at ca. 1
exhibited a small jump at
. The peak position and area of the three peaks did not change much at the transition. The structural changes were minimal at
. The QENS experiments demonstrated that the relaxation time of the interlayer motion increased tenfold at
, while those of other motions were monotonous in the whole temperature region. The structural and dynamical changes are characteristic of the L-LC transition in imidazolium-based ionic liquids.