Chemo-Mechanical Coupling in Reactive Droplets

Abstract

Chemo-mechanical coupling is studied in droplets containing an oscillating Belousov−Zhabotinsky (BZ) reaction medium surrounded by a solution of lipids in n-decane. We identified experimental conditions at which the oxidation state of the catalyst significantly changes the interfacial tensions of the BZ droplet. During oxidation episodes, a fraction of the catalyst incorporates into the membrane, whereas during the slower reduction phase it returns to the aqueous phase. The catalyst is partly replaced by lipids that were originally dissolved in the organic phase, thus increasing the surface of the droplet. As a result of this increase in surface area, a droplet placed in a trench on the bottom of the reactor periodically elongates in phase with the chemical oscillations.

Evolution of Self‐Propelled Objects: From the Viewpoint of Nonlinear Science

“…Therefore, the balance of surface tension on the gel surface is broken when the chemical wave is generated in the gel, and thus the gel moves toward the reduced region because the contact angle to the oxidized gel is smaller than to the reduced one (Figure b). In a similar fashion, difference in the contact angle also generates expansion‐shrinkage oscillation of a BZ droplet on a solid surface …”

“…In fact, phototactic behavioro ft he BZ dropletm otion has been realized, in which the droplets tarts to move toward the bright region if there is as patial gradient of light intensity. [131] In the above examples, ac hemical wave breaks the symmetry,a nd the object gets ad riving force originated from difference in the surface tensions or contact angles. However,a BZ gel floated on aw ater surface can spontaneously move concurrent with ac hemical wave propagation inside the gel.…”

“…In as imilar fashion,d ifference in the contact angle also generates expansion-shrinkage oscillationo faBZ dropleto nasolid surface. [131] In the above examples, ac hemical wave breaks the symmetry,a nd the object gets ad riving force originated from difference in the surface tensions or contact angles. As ar esult, characteristic motions such as reciprocating motion and photosensitive motion are generated.…”

Polymer-encapsulated organic nanoparticles for fluorescence and photoacoustic imaging

“…36,37 As compared to specific structural modification to synthesize each CPE, 38,39 encapsulation of CPs using biocompatible polymers emerges as one of the most convenient strategies to transform neutral CPs into aqueous media. 31,32,40,41 The marriage between biocompatible polymer matrices and functional CPs or AIE fluorogens thus offers new insights into the development of highly fluorescent polymer encapsulated organic nanoparticles with unprecedented brightness for bioimaging. 31,42 Different from fluorescence imaging which requires probes with bright fluorescence, recent discovery reveals that low fluorescence CP nanoparticles with NIR absorption are ideal probes for photoacoustic (PA) imaging.…”

Marangoni instability in the iodate–arsenous acid reaction front

“…Surface tension gradients along air/liquid/solid interfaces in systems with a free surface may create self-motion, [2][3][4] oscillations, 5 or yield complex shapes. [6][7][8] Autonomous motion has been observed in the dissolution of dichloromethane drops on surfactant containing water yielding interesting patterns. 6 The pulsations of the liquid droplets have been modeled by considering simple springs.…”