Measurement of the interface tension of smectic membranes in water

Harth, Kirsten; Stannarius, Ralf

doi:10.1039/c3cp44055a

Cited by 10 publications

(14 citation statements)

References 28 publications

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“…In a previous investigation of smectic films (of a different material than in this study) in a water/surfactant mixture, an interface tension of the order of 6.3 mN/m was reported. 59 In absence of surfactants, like in the present case, the interface tension to water is expected to be considerably larger, 60 but no reliable values exist.…”

Section: Droplet Impactmentioning

confidence: 63%

Impact and Embedding of Picoliter Droplets into Freely Suspended Smectic Films

et al. 2014

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We study the impact of liquid microdroplets on thin freely suspended smectic films. Such films are very thin but robust objects that can serve as model systems for quasi-two-dimensional liquids. Droplet velocities and sizes determine the character of the collisions. The dynamics of the integration of droplets into the film can be divided into three phases, starting with the impact and a dissipation of the kinetic energy, followed by a balancing of capillary forces within fractions of a second. The analysis of the droplet shape evolution with high-speed imaging allows us to study the dynamics of this process. The final phase, formation of a meniscus of smectic material, takes several seconds up to minutes.

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Section: Droplet Impactmentioning

confidence: 63%

Impact and Embedding of Picoliter Droplets into Freely Suspended Smectic Films

et al. 2014

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“…Equilibrium interface tensions at c E 0.5 wt%, well above the cmc, have been reported earlier. 7 For c 4 cmc, the interface tensions only slightly increases with decreasing surfactant concentration, by less than 1 mN m À1 between 0.05 wt% and 0.5 wt%. A similar trend was also observed by Kumar et al 33 for the SDBS solution/air interface.…”

Section: Conclusion and Summarymentioning

confidence: 90%

“…The contact line of the air bubble to the smectic film apparently splits the image of the air bubble into an upper and a lower cap. In our previous study, 7 it was justified to approximate these regions by two sphere caps. In the present work, particularly at sub-cmc concentrations, we often had to cope with a different geometry of the air bubble, with the contact line below its equator (see Fig.…”

Section: Calculating the Interface Tensionmentioning

confidence: 99%

“…Such centimeter-sized bubbles have been reported earlier. 6,7 Anchoring transitions induced by surfactants can be useful in chemical or biological sensors. 8 While surface tensions of several liquid crystal phases with respect to air have been studied extensively see, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…A recently introduced method allows the simple and exact measurement of interface tensions of smectic LCs in a surrounding liquid. 7 Instead of the very small buoyancy of a smectic droplet in water, the buoyancy of a millimeter-sized air bubble trapped beneath the membrane induces an easily measurable membrane deformation. The method depends on the possibility to prepare a smectic film in the surfactant solution or pure water, and trapping of an air bubble.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic interface tension of a smectic liquid crystal in anionic surfactant solutions

Harth

Shepherd

Honaker

et al. 2015

Phys. Chem. Chem. Phys.

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The interface tension of a smectic liquid crystal with respect to a surrounding ionic surfactant solution is investigated at concentrations above and below the critical micelle concentration (cmc). A simple measurement technique has been developed recently [Phys. Chem. Chem. Phys., 2013, 15, 7204], based on the geometrical analysis of the shape of smectic bubbles in water that are deformed by the buoyancy of trapped air bubbles. After preparation of the smectic membranes in the solution, we measure both the time dependence of their dynamic interface tension as well as the asymptotically reached static tension values. These are established about 15 minutes after the membrane preparation. At large enough concentrations of the surfactant (above the critical micelle concentration), the interface tension drops to 6 mN m(-1). At the lowest possible surfactant concentrations in our experiment, the equilibrium tension reaches 20 mN m(-1), which is almost equal to the smectic surface tension respective to air. The tension of a freshly drawn film exceeds this value by far.

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Realization of hydrodynamic experiments on quasi-2D liquid crystal films in microgravity

Clark

Eremin

Glaser

et al. 2017

Advances in Space Research

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Freely suspended films of smectic liquid crystals are unique examples of quasi two-dimensional fluids. Mechanically stable and with quantized thickness of the order of only a few molecular layers, smectic films are ideal systems for studying fundamental fluid physics, such as collective molecular ordering, defect and fluctuation phenomena, hydrodynamics, and nonequilibrium behavior in two dimensions (2D), including serving as models of complex biological membranes. Smectic films can be drawn across openings in planar supports resulting in thin, meniscus-bounded membranes, and can also be prepared as bubbles, either supported on an inflation tube or floating freely. The quantized layering renders smectic films uniquely useful in 2D fluid physics. The OASIS team has pursued a variety of ground-based and microgravity applications of thin liquid crystal films to fluid structure and hydrodynamic problems in 2D and quasi-2D systems. Parabolic flights and sounding rocket experiments were carried out in order to explore the shape evolution of free floating smectic bubbles, and to probe Marangoni effects in flat films. The dynamics of emulsions of smectic islands (thicker regions on thin background films) and of microdroplet inclusions in spherical films, as well as thermocapillary effects, were studied over extended periods within the OASIS (Observation and Analysis of Smectic Islands in Space) project on the International Space Station. We summarize the technical details of the OASIS hardware and give preliminary examples of key observations.

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Measurement of the interface tension of smectic membranes in water

Cited by 10 publications

References 28 publications

Impact and Embedding of Picoliter Droplets into Freely Suspended Smectic Films

Impact and Embedding of Picoliter Droplets into Freely Suspended Smectic Films

Dynamic interface tension of a smectic liquid crystal in anionic surfactant solutions

Realization of hydrodynamic experiments on quasi-2D liquid crystal films in microgravity

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