Dynamic deformations and forces in soft matter

Chan, Derek Y. C.; Klaseboer, Evert; Manica, Rogério

doi:10.1039/b907953j

Cited by 47 publications

(58 citation statements)

References 21 publications

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“…due to buoyancy) has also been studied by perturbation methods. The result shows that the central separation evolves with an exponential dependence on time under a constant external force, F ext [23,85]:…”

Section: Axisymmetric Dropsmentioning

confidence: 95%

Theory of non-equilibrium force measurements involving deformable drops and bubbles

Chan

Klaseboer

Manica

2011

Advances in Colloid and Interface Science

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125

148

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Section: Axisymmetric Dropsmentioning

confidence: 95%

Theory of non-equilibrium force measurements involving deformable drops and bubbles

Chan

Klaseboer

Manica

2011

Advances in Colloid and Interface Science

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125

148

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“…2A (curve EFGH) has been investigated by perturbation analysis of the governing equations for the approach-retract collision in the AFM geometry (27) and in the Hele-Shaw cell geometry of microfluidic cell experiments (28). During approach, the deformable bubble surfaces respond to the repulsive hydrodynamic pressure by flattening so that the distance of closest approach decreases slower than would be for nondeforming bubbles.…”

Section: Discussionmentioning

confidence: 99%

Dynamic interactions between microbubbles in water

Vakarelski

Manica²,

Tang³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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188

232

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The interaction between moving bubbles, vapor voids in liquid, can arguably represent the simplest dynamical system in continuum mechanics as only a liquid and its vapor phase are involved. Surprisingly, and perhaps because of the ephemeral nature of bubbles, there has been no direct measurement of the time-dependent force between colliding bubbles which probes the effects of surface deformations and hydrodynamic flow on length scales down to nanometers. Using ultrasonically generated microbubbles (∼100 μm size) that have been accurately positioned in an atomic force microscope, we have made direct measurements of the force between two bubbles in water under controlled collision conditions that are similar to Brownian particles in solution. The experimental results together with detailed modeling reveal the nature of hydrodynamic boundary conditions at the air/water interface, the importance of the coupling of hydrodynamic flow, attractive van der Waals-Lifshitz forces, and bubble deformation in determining the conditions and mechanisms that lead to bubble coalescence. The observed behavior differs from intuitions gained from previous studies conducted using rigid particles. These direct force measurements reveal no specific ion effects at high ionic strengths or any special role of thermal fluctuations in film thickness in triggering the onset of bubble coalescence.bubble collision | colloidal forces | hydrodynamic interaction | soft matter | thin films B ubble dynamics has attracted scientific interest since the time of Leonardo da Vinci (1), yet the observation that some simple salts can prevent bubble coalescence at high concentrations whereas others cannot remains unexplained even after over a decade of systematic study (2). In themselves, bubble-bubble interactions are very important because they feature in diverse situations, from the basis of the bends in deep-sea divers, to the development of effective ultrasonic imaging contrast agents, through to enhancing the quality of champagne. However, the delicate and ephemeral nature of bubbles poses significant technical challenges to the precise quantification of the force-displacement characteristics of bubble collisions.As a vapor phase in a liquid, the interaction between bubbles should be amenable to a simple explanation in terms of basic physical and chemical principles. A detailed understanding of the interaction between moving bubbles can provide the foundation on which to study the fundamental coupling between forces and deformations that defines the dynamic interaction on the nanoscale between soft-matter materials, such as bubbles, drops, emulsions, biological cells, soft tissues, and gels. Here we report direct measurements of the dynamic force between two deformable microbubbles in water under a variety of accurately controlled collision protocols. The typical collision velocities are in the regime of Brownian particles of comparable dimensions. The experimental conditions are such that only attractive van der Waals-Lifshitz forces and hydrodynami...

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“…[5,[13][14][15][16] A convenient way of creating oriented wrinkles is preparation of a hard surface layer on stretched elastomers and subsequent release of stretching, as reported in ref. [17][18][19][20][21][22] and also reviewed in ref. [8,23] Figure 2 illustrates the principle of wrinkleformation.…”

mentioning

confidence: 99%

Fabrication of Artificial Petal Sculptures by Replication of Sub‐micron Surface Wrinkles

Schweikart

Zimin

Handge

et al. 2010

Macro Chemistry & Physics

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In this contribution, we discuss wrinkling as a process resulting in well‐defined periodic micron‐sized structures, as known from the interface of several plant cells. We show possible pathways to transfer this principle to artificial materials such as epoxy resins or polymers. While topographical structuring of surfaces by wrinkling is meanwhile well established for elastomers like poly (dimethyl siloxane), so far the step towards other classes of materials has not been taken. This puts several limitations to potential applications of artificial wrinkled structures, as elastomers show poor dimensional stability, low optical quality, and tend to swell in organic solvents. As well, artificial structures formed by wrinkling are not tension‐free on the microscopic level, which makes them metastable. Residual mechanical tensions can affect dimensional stability on long timescales. We introduce two processes, micro thermoforming and molding, as means to overcome these restrictions and to pattern non‐elastomeric materials by using wrinkled elastomers as templates. The two approaches allow the formation of negative and positive replicas and allow the transfer of sub‐micron features with high fidelity.magnified image

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Dynamic deformations and forces in soft matter

Abstract: The ability of soft matter such as drops and bubbles to change shape dynamically Recent studies of dynamic interactions include the use of: the surface force apparatus to measure the time-dependent profiles of thinning films between a

Cited by 47 publications

References 21 publications

Theory of non-equilibrium force measurements involving deformable drops and bubbles

Theory of non-equilibrium force measurements involving deformable drops and bubbles

Dynamic interactions between microbubbles in water

Fabrication of Artificial Petal Sculptures by Replication of Sub‐micron Surface Wrinkles

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