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阿部 洋*; 根本 文也*; 廣井 孝介; 大石 一城*; 高田 慎一
Journal of Molecular Liquids, 346, p.117035_1 - 117035_6, 2022/01
被引用回数:6 パーセンタイル:61.81(Chemistry, Physical)In this study, monodispersive nanoconfined water ("water pocket") is organized spontaneously in hydrophilic ionic liquid (IL). The IL is 1-alkyl-3-methylimidazolium nitrate ([Cmim][NO] = 2, 6, and 8). By small-angle neutron scattering (SANS), DO aggregations in the IL are detected. There are no SANS peaks for [Cmim][NO]-DO, but, in [Cmim][NO]- mol% DO, a SANS peak can be observed at mol%. The peak intensity, position, and profile change according to water concentration and temperature. Pure [Cmim][NO] has a distinct SANS peak, reflecting on the nanodomains at room temperature. Above 70 mol%, the SANS peak of [Cmim][NO]-DO sharply increases and shifts to the low-Q position. The water pocket develops proportionate to water concentration, and its morphologies are visualized using an bead model. The alkyl chain length dependence of the water pocket is clarified by a three-dimensional reconstruction method.
根本 文也*; 山田 悟史*; 日野 正裕*; 青木 裕之; 瀬戸 秀樹*
Soft Matter, 18(3), p.545 - 553, 2022/01
被引用回数:2 パーセンタイル:13.57(Chemistry, Physical)Surface aligning agents, such as amphiphilic surfactants, are widely used to control the initial alignment of nematic liquid crystals (NLCs) in liquid crystal displays (LCDs). Generally, these agents are first coated on a substrate prior to NLC introduction. When mixed with NLCs, long alkyl chain amphiphilic agent additives may control the NLC alignment without requiring pretreatment because they may spontaneously form an adsorbed layer at the solid-NLC interface. These self-assembled layers (SALs) appear promising in the effective control of the initial alignment of LCDs. However, direct observation of the adsorbed layer structure in contact with the NLCs is challenging due to probe limitations. Furthermore, the areal densities and alignments of the amphiphiles adsorbed from NLCs at the solid-NLC interface are not previously reported. Herein, the structure of the surface aligning agent -hexadecyltrimethylammonium-d bromide (d-CTAB) was investigated at the silicon-NLC interface using neutron reflectometry (NR), which indicated that the CTAB self-assembled as a monolayer, with its alignment dependent on the amphiphile concentration. At low amphiphile concentrations, the alignment of the SAL and NLCs was parallel to the substrate. With increasing amphiphile concentration, the number of amphiphiles attached to the substrate increased within the framework of the Gibbs monolayer, with the alignment of the amphiphiles and NLCs becoming perpendicular to the substrate. The experimental setup used here is comparable to those of more natural systems, such as those found in the alignment of NLCs in LCDs.
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:20 パーセンタイル:70.54(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 CmimPF ( = 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.