Light-Driven Locomotion of Bubbles

Ito, Masaya; Mayama, Hiroyuki; Asaumi, Yuta; Nakamura, Yoshinobu; Fujii, Syuji

doi:10.1021/acs.langmuir.9b03356

Cited by 13 publications

(9 citation statements)

References 58 publications

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“…They can use different mechanisms of motion and differ in physical state. Active objects can be solid (porous), , liquid, − and even gaseous, and their motion can be conditioned by diffusiophoresis, , thermophoresis, electrophoresis, magnetic field, and Marangoni flow.…”

Section: Introductionmentioning

confidence: 99%

Crystallization of Active Emulsion

et al. 2021

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Active matter contains self-propelled units able to convert stored or ambient free energy into motion. Such systems demonstrate amazing features related to the phenomenon of self-organization and phase transitions and can be used for the development of artificial materials and machines that operate away from equilibrium. Significant advances in the fabrication of active matter were achieved when studying low-density gas and small crystallites. However, the technique of preparation of active matter, where one can observe the formation of stable crystals, is extremely challenging. Here, we describe the novel method to obtain a stable 2D crystal in the active octane-in-water emulsion during the process of heterogeneous crystallization. Active motion is driven by the Marangoni flow emerging at the interface of the droplet. It is established that the crystal volume increases linearly in time in the process of crystallization. Moreover, the dependence of the crystal growth rate on the average velocity of droplets motion in the emulsion has a maximum. The kinetics of crystal growth is defined by a competition between the processes of attachment and detachment of droplets from the crystal surface. Crystallization proceeds via condensation of droplets from the gas phase through the formation of liquid as an intermediate phase, which covers the crystal surface with a thin layer. Inside the liquid layer the bond-orientational order of droplets decreases from the crystal surface toward the gas phase. We anticipate our study to be a starting point for the development of new materials and technologies on the basis of nonequilibrium droplet systems.

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Section: Introductionmentioning

confidence: 99%

Crystallization of Active Emulsion

et al. 2021

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“…Moreover, the fragments of dried foams showed an iridescent character under white light. The pH-dependent formation of aqueous foams/bubbles using the polymer particles studied in this study should help in understanding the stability of foams/bubbles utilized in industry including food, textile, petroleum, cosmetic, pharmaceutical and personal care product sections [2,[59][60][61][62].…”

Section: Discussionmentioning

confidence: 99%

pH-Dependent Foam Formation Using Amphoteric Colloidal Polymer Particles

et al. 2020

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Near-monodispersed micrometer-sized polystyrene (PS) particles carrying amidino and carboxyl groups on their surfaces were synthesized by soap-free emulsion polymerization using an amphoteric free radical initiator. The resulting amphoteric PS particles were characterized in terms of diameter, morphology, disperibility in aqueous media and surface charge using scanning electron microscopy (SEM), optical microscopy (OM), sedimentation rate and electrophoretic measurements. At pH 2.0, where the amidino groups are protonated (positively charged), and at pH 11.0, where the carboxyl groups are deprotonated (negatively charged), the PS particles were well dispersed in aqueous media via electrostatic repulsion. At pH 4.8, where the surface charges are neutral, the PS particles were weakly aggregated. Furthermore, it was confirmed that the PS particles can function as a pH-sensitive foam stabilizer: foamability and foam stability were higher at pH 2.0 and 4.8, where the PS particles can be adsorbed to the air–water interface, and lower at pH 11.0, where the PS particles tend to disperse in bulk aqueous medium. SEM and OM studies indicated that hexagonally close-packed arrays of PS particles were formed on the bubble surfaces and moiré patterns were observed on the dried foams. Moreover, the fragments of dried foams showed iridescent character under white light.

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“…Active matter represents a system consisting of self-propelled units capable of converting the stored or ambient free energy into systematic movement. , The world of active matter is extremely diverse. − Active objects can differ in scales, the aggregate state, and the principle of motion. − Since active systems can be driven far from equilibrium by continuous energy consumption, they can demonstrate a great variety of non-trivial modes of collective dynamics. − One of these modes represents the self-organization of active objects into vortex-like structures, in which they are moving either clockwise or anti-clockwise. ,− Collective dynamical chirality is commonly obtained in the systems of active objects with individual structural and/or dynamical chirality. , Due to this, a natural question ariseswhether collective dynamical chirality can be realized in the case of achiral active objects. An affirmative answer to this question was given by Jiang et al in a study .…”

Section: Introductionmentioning

confidence: 99%

Self-Organization of Active Droplets into Vortex-like Structures

et al. 2021

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Natural or artificial active objects can demonstrate mirror asymmetry of collective motion when they are moving coherently in a vortex. The majority of known cases related to the emergence of collective dynamical chirality are referred to as active objects with individual structure chirality and/or dynamical chirality. Here, we demonstrate that dynamically and structurally achiral active droplets can self-organize into vortex-like structures. Octane droplets dispersed in the aqueous solution of an anionic surfactant are activated with ammonia addition. The motion of droplets is due to the Marangoni flow emerging at the interfaces of the droplets. We found out that different modes of vortex motion of droplets in the emulsion can arise depending on the size of the region that confines the motion of the droplets and their number density and velocity.

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Light-Driven Locomotion of Bubbles

Cited by 13 publications

References 58 publications

Crystallization of Active Emulsion

Crystallization of Active Emulsion

pH-Dependent Foam Formation Using Amphoteric Colloidal Polymer Particles

Self-Organization of Active Droplets into Vortex-like Structures

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