Nanorheology of liquid crystal thin films confined between interfaces with anisotropic molecular orientations

Zhang, Xiangjun; Zhang, Xiaohao; Qiao, Xiaoxi; Guo, Yanbao; Tian, Yu; Meng, Yonggang

doi:10.1007/s10404-014-1505-9

Cited by 7 publications

(3 citation statements)

References 31 publications

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“…Many studies have shown that the anchoring effect of a surface has great influence on the flow behavior of LCs. For example, Zhang et al [8] investigated the nanorheology of 5CB LC confined in a 520 nm thick slab using a quartz-crystal microbalance. Their results showed that the effective viscosity of 5CB changes in the range of 11.4-30.7 mPa s under different surface-anchoring conditions.…”

Section: Doi: 101002/adts202200346mentioning

confidence: 99%

Molecular Dynamics Simulations on the Flow Behavior of 5CB Liquid Crystal Sandwiched Between Iron Walls

Chen

Sun

Xiao

et al. 2022

Advcd Theory and Sims

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The 4-n-pentyl-4′-cyano biphenyl (5CB) liquid crystal (LC) sandwiched and sheared between atomically flat and grooved iron walls, respectively, is simulated using molecular dynamics, and the flow behavior of the system under confinement, pressure, and shear is investigated. The order parameter P 2 , velocity, and density of 5CB are profiled as a function of distance from the walls using a block analysis method. The flow-alignment phenomenon is reproduced, and alignment angles ranging from 11.3°to 13.9°are observed. The competition between the elastic effect of the surface and viscous effect of the flow on the orientation of the 5CB molecules is investigated. The P 2 of 5CB located in the vicinity of the grooved walls is higher than that of the flat walls, while this difference is negligible in the case of 5CB distanced from the walls. Instead of boundary slip or Couette flow, the velocity profiles reveal a boundary condition (BC) of central localization, which is very different from the assumed Couette flow BC in most analytical models of LC flow. This work enhances the current molecular-scale understanding of the flow behavior of confined liquid crystals and provides additional insights into the phenomenon.

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Section: Doi: 101002/adts202200346mentioning

confidence: 99%

Molecular Dynamics Simulations on the Flow Behavior of 5CB Liquid Crystal Sandwiched Between Iron Walls

Chen

Sun

Xiao

et al. 2022

Advcd Theory and Sims

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“…They found that the effective viscosity decreases as the molecular orientation is parallel to the shear direction, resulting in a reduction in the coefficient of friction. [25][26][27] In addition, the orientation of the molecules can be controlled by an electric field that promotes the alignment of the molecules. [28] At critical electric field intensity, however, the liquid trapped in the lubrication gap loses its fluidity and a "freezing" of the liquid is observed.…”

Section: Introductionmentioning

confidence: 99%

“…Some researchers have studied the relation between molecular orientation and friction by using a specific structured surface to induce a targeted orientation of the molecules. They found that the effective viscosity decreases as the lubricant molecules become oriented parallel to the shear direction, resulting in a reduction in the COF. − In addition, the orientation of the molecules can be controlled by an electric field that promotes the alignment of the molecules . At a critical electric field intensity, however, the liquid trapped in the lubrication gap loses its fluidity and a “freezing” of the liquid is observed. , Jing et al have analyzed theoretically the thin-film lubrication mechanism on the basis of thermodynamics.…”

Section: Introductionmentioning

confidence: 99%

Thin-Film Lubrication in the Water/Octyl β-d-Glucopyranoside System: Macroscopic and Nanoscopic Tribological Behavior

et al. 2019

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The friction properties of the water-based surfactant system C8 (octyl ß-D-glucopyranoside) are investigated both at the macro and nanoscale in ring-on-plate and AFM friction experiments, respectively. Surface characterization and measurement of the friction gap during sliding, together with the tribological behavior show a strong shear rate dependence of the friction behavior. High shear rates of approximately 10 6 s -1 in the macroscopic friction experiments induce a molecular alignment of the surfactants in the friction gap. This generates an anisotropic viscosity which allows to carry a high load, but exhibits low viscosity in shear direction. When the nanoscale and macroscale friction experiments are normalized to the same shear rate, almost identical frictional behavior is observed in the two regimes.

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Recent advances in quartz crystal microbalance with dissipation monitoring: Phase transitions as descriptors for specific lipid membrane studies

Cordoyiannis

Bar

Losada-Pérez

2021

Advances in Biomembranes and Lipid Self-Assembly

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Nanorheology of liquid crystal thin films confined between interfaces with anisotropic molecular orientations

Cited by 7 publications

References 31 publications

Molecular Dynamics Simulations on the Flow Behavior of 5CB Liquid Crystal Sandwiched Between Iron Walls

Molecular Dynamics Simulations on the Flow Behavior of 5CB Liquid Crystal Sandwiched Between Iron Walls

Thin-Film Lubrication in the Water/Octyl β-d-Glucopyranoside System: Macroscopic and Nanoscopic Tribological Behavior

Recent advances in quartz crystal microbalance with dissipation monitoring: Phase transitions as descriptors for specific lipid membrane studies

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