Run-and-halt motility of droplets in response to light

Ryabchun, Alexander; Babu, Dhanya; Movilli, Jacopo; Stuart, Marc C. A.; Katsonis, Nathalie

doi:10.1016/j.chempr.2022.06.017

Cited by 10 publications

(14 citation statements)

References 62 publications

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“…A much more elegant and less disruptive approach is to use photoswitchable surfactants ,− or surfactants that are reactive to other stimuli, , which can yield responsive interfaces and trigger property changes on larger length scales through changes in surface tension and interfacial composition. , We note that responsive materials are the basis to develop adaptive materials or interfaces, which are able to provide feedback arising from the joint actione.g., of multiple responsive unitswith the possibility to precondition the system …”

Section: Introductionmentioning

confidence: 99%

Photo-Responsive Control of Adsorption and Structure Formation at the Air–Water Interface with Arylazopyrazoles

et al. 2023

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Smart interfaces that are responsive to external triggers such as light are of great interest for the development of responsive or adaptive materials and interfaces. Using alkyl-arylazopyrazole butyl sulfonate surfactants (alkyl-AAP) that can undergo E/Z photoisomerization when irradiated with green (E) and UV (Z) lights, we demonstrate through a combination of experiments and computer simulations that there can be surprisingly large changes in surface tension and in the molecular structure and order at air−water interfaces. Surface tensiometry, vibrational sumfrequency generation (SFG) spectroscopy, and neutron reflectometry (NR) are applied to the study of custom-synthesized AAP surfactants with octyland H-terminal groups at air−water interfaces as a function of their bulk concentration and E/Z configuration. Upon photoswitching, a drastic influence of the alkyl chain on both the surface activity and the responsiveness of interfacial surfactants is revealed from changes in the surface tension, γ, where the largest changes in γ are observed for octyl-AAP (Δγ ∼ 23 mN/m) in contrast to H-AAP with Δγ < 10 mN/m. Results from vibrational SFG spectroscopy and NR show that the interfacial composition and the molecular order of the surfactants drastically change with E/Z photoisomerization and surface coverage. Indeed, from analysis of the S−O (head group) and C−H vibrational bands (hydrophobic tail), a qualitative analysis of orientational and structural changes of interfacial AAP surfactants is provided. The experiments are complemented by resolution of thermodynamic parameters such as equilibrium constants from ultra-coarse-grained simulations, which also capture details like island formation and interaction parameters of interfacial molecules. Here, the interparticle interaction ("stickiness") and the interaction with the surface are adjusted, closely reflecting experimental conditions.

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Section: Introductionmentioning

confidence: 99%

Photo-Responsive Control of Adsorption and Structure Formation at the Air–Water Interface with Arylazopyrazoles

et al. 2023

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“…122,123 Similarly, oil droplets can be propelled in the proximity of azobenzene-stabilized micelles. 124 Changing the wavelength of the light induces a change in the micelle geometry, which impacts the movement pattern of the droplets, resulting in a run-and-halt behavior. 124 Further, Janus emulsions stabilized with AzoTAB under blue light irradiation move toward a UV light spot around which they self-assemble in an ordered fashion (Figure 3b).…”

Section: ■ Active Matter Actuation By Light Intensitymentioning

confidence: 99%

“…124 Changing the wavelength of the light induces a change in the micelle geometry, which impacts the movement pattern of the droplets, resulting in a run-and-halt behavior. 124 Further, Janus emulsions stabilized with AzoTAB under blue light irradiation move toward a UV light spot around which they self-assemble in an ordered fashion (Figure 3b). 114 Finally, fatty acid droplets containing photosensitive spiropyran can move toward visible light sources and away from UV light sources, thus enabling their manipulation in three dimensions.…”

Section: ■ Active Matter Actuation By Light Intensitymentioning

confidence: 99%

“…For example, this principle enabled the omnidirectional manipulation of oil droplets and liquid marbles floating on the surface of an aqueous solution of AzoTAB surfactants. By changing the wavelength of the light used to illuminate the edge of the droplets or liquid marbles, it was possible to reversibly repel them from the incident beam (UV illumination) or attract them toward it (blue illumination). , Similarly, oil droplets can be propelled in the proximity of azobenzene-stabilized micelles . Changing the wavelength of the light induces a change in the micelle geometry, which impacts the movement pattern of the droplets, resulting in a run-and-halt behavior .…”

Section: Actuation By Other Properties Of Lightmentioning

confidence: 99%

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Light, Matter, Action: Shining Light on Active Matter

Rey

Volpe

2023

ACS Photonics

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Light carries energy and momentum. It can therefore alter the motion of objects on the atomic to astronomical scales. Being widely available, readily controllable, and broadly biocompatible, light is also an ideal tool to propel microscopic particles, drive them out of thermodynamic equilibrium, and make them active. Thus, light-driven particles have become a recent focus of research in the field of soft active matter. In this Perspective, we discuss recent advances in the control of soft active matter with light, which has mainly been achieved using light intensity. We also highlight some first attempts to utilize light's additional properties, such as its wavelength, polarization, and momentum. We then argue that fully exploiting light with all of its properties will play a critical role in increasing the level of control over the actuation of active matter as well as the flow of light itself through it. This enabling step will advance the design of soft active matter systems, their functionalities, and their transfer toward technological applications.

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“…Recent studies have investigated the control of speed and dynamic states of such microswimmers in response to externally applied stimuli such as temperature [22,23] * c.c.maass@utwente.nl or illumination [24][25][26][27][28][29][30]. On heating, physical intuition suggests that motion should accelerate and destabilise, either by the increase of translational and rotational diffusion with decreasing viscosity, or by increased activity from the molecular thermodynamics driving the motion.…”

Section: Introductionmentioning

confidence: 99%

Arrested on heating: controlling the motility of active droplets by temperature

Ramesh¹,

Chen²,

Räder³

et al. 2023

Preprint

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One of the challenges in tailoring the dynamics of active, self-propelling agents lies in arresting and releasing these agents at will. Here, we present an experimental system of active droplets with thermally controllable and reversible states of motion, from unsteady over meandering to persistent to arrested motion. These states depend on the Péclet number of the chemical reaction driving the motion, which we can tune by using a temperature sensitive mixture of surfactants as a fuel medium. We quantify the droplet dynamics by analysing flow and chemical fields for the individual states, comparing them to canonical models for autophoretic particles. In the context of these models, we are able to observe in situ the fundamental first transition between the isotropic, immotile base state and self-propelled motility.

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Run-and-halt motility of droplets in response to light

Cited by 10 publications

References 62 publications

Photo-Responsive Control of Adsorption and Structure Formation at the Air–Water Interface with Arylazopyrazoles

Photo-Responsive Control of Adsorption and Structure Formation at the Air–Water Interface with Arylazopyrazoles

Light, Matter, Action: Shining Light on Active Matter

Arrested on heating: controlling the motility of active droplets by temperature

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