Pendulum viscometer: A new method for measurement of Miȩsowicz nematic shear viscosity coefficients η1 and η2

Janik, J. A.; Krol-Otwinowska, Agnieszka; Sokołowska, Dagmara; Mościcki, Józef K.

doi:10.1063/1.2387879

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…The Miesowicz viscosity coefficient g 2 was measured using the pendulum viscometer [22]. The viscometer heart is a glass plate attached to a long pendulum arm, and submersed in a studied liquid.…”

Section: Experimental Methodsmentioning

confidence: 99%

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The Influence of Natural and Model Nanoinclusions on the Properties of Nematic Phase

Janik-Kokoszka

Mościcki

2011

Molecular Crystals and Liquid Crystals

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The present work is focused on the investigation of the influence of a small volume fraction of nanoinclusions on the Miesowicz viscosity coefficient g 2 of the nematic phase. Two kinds of nanoinclusions in the nematic phase have been studied: natural (smectic cybotactic clusters) and solid impurities (AEROSIL 1 380). The volume fraction of nanoinclusions was estimated using the Batchelor model. This allowed in turn for calculating their number density. For cybotactic clusters, we found that their number in the nematic phase of octyloxycyanbiphenyl (8OCB) goes over the maximum when approaching the nematic-smectic phase transition. To shed some light on that finding we also studied g 2 for a number of different AEROSIL 1 380 suspensions in the nematic host of 4-trans-4 0 -n-hexylcyclohexyl isothiocyanatobenzene (6CHBT).

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Section: Experimental Methodsmentioning

confidence: 99%

“…Due to the viscous force, the pendulum arm with the plate performs damped oscillations from which the viscosity coefficient is calculated. Liquid crystalline phase under study was oriented with a 0.5 T horizontal magnetic field generated by a classic electromagnet [22].…”

Section: Experimental Methodsmentioning

confidence: 99%

The Influence of Natural and Model Nanoinclusions on the Properties of Nematic Phase

Janik-Kokoszka

Mościcki

2011

Molecular Crystals and Liquid Crystals

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“…So far, the effective viscosity of LCs has been measured experimentally by using some kinds of viscometers with external fields. For example, Miesowicz [20,21], Hennel et al [22] and Janik et al [23] used viscometers employing pendulum oscillation in LCs. The anisotropic viscosities of nematic LCs were measured by monitoring the amplitude of damped oscillation of a plate submersed in an LC sample with an external magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Quick measurement of electrorheological effect for small amounts of nematic liquid crystal

Tadokoro

Hosomi

Nakano

2015

Meas. Sci. Technol.

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A quick measurement method of effective viscosity, employing damped oscillation between two parallel plates, was proposed to examine the electrorheological (ER) effect for small amounts of nematic liquid crystal (LC). To demonstrate the validity of the method, the viscosity measurements were conducted for ordinary liquids [polyalphaolefins (PAOs)] and a nematic LC [4-pentyl-4′-cyanobiphenyl (5CB)] by using a newly developed apparatus that embodied the measurement principle. The viscosity measurements for PAOs showed that when the film thickness is in the submillimeter range (e.g. 0.2 mm), this method provides reliable values of the effective viscosity. The viscosity measurement for 5CB showed that this method evaluates the ER effect with a few dozen cubic millimeters of the sample (e.g. 16 mm3) under the application of a voltage (e.g. 0 to 300 V). It was confirmed that the effective viscosities of 5CB measured at various conditions were scaled to a single master curve as a function of the applied voltage, effective velocity and film thickness.

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Self-reporting and self-regulating liquid crystals

Kim

Wang

Mondkar

et al. 2018

Nature

137

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Liquid crystals (LCs) are anisotropic fluids that combine the long-range order of crystals with the mobility of liquids. This combination of properties has been widely used to create reconfigurable materials that optically report information about their environment, such as changes in electric fields (smart-phone displays) , temperature (thermometers) or mechanical shear , and the arrival of chemical and biological stimuli (sensors). An unmet need exists, however, for responsive materials that not only report their environment but also transform it through self-regulated chemical interactions. Here we show that a range of stimuli can trigger pulsatile (transient) or continuous release of microcargo (aqueous microdroplets or solid microparticles and their chemical contents) that is trapped initially within LCs. The resulting LC materials self-report and self-regulate their chemical response to targeted physical, chemical and biological events in ways that can be preprogrammed through an interplay of elastic, electrical double-layer, buoyant and shear forces in diverse geometries (such as wells, films and emulsion droplets). These LC materials can carry out complex functions that go beyond the capabilities of conventional materials used for controlled microcargo release, such as optically reporting a stimulus (for example, mechanical shear stresses generated by motile bacteria) and then responding in a self-regulated manner via a feedback loop (for example, to release the minimum amount of biocidal agent required to cause bacterial cell death).

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Pendulum viscometer: A new method for measurement of Miȩsowicz nematic shear viscosity coefficients η1 and η2

Cited by 6 publications

References 18 publications

The Influence of Natural and Model Nanoinclusions on the Properties of Nematic Phase

The Influence of Natural and Model Nanoinclusions on the Properties of Nematic Phase

Quick measurement of electrorheological effect for small amounts of nematic liquid crystal

Self-reporting and self-regulating liquid crystals

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