Visualization of the Mechanical Wave Effect on Liquid Microphases and Its Application for the Tuning of Dissipative Soft Microreactors

Abstract

The development of approaches for creation of adaptive and stimuli-responsive chemical systems is particularly important for chemistry, materials science, and biotechnology. The understanding of response mechanisms for various external forces is highly demanded for the rational design of task-specific systems. Here, we report direct liquid-phase scanning electron microscopy (SEM) observations of the high frequency sound-wave-driven restructuring of liquid media on the microlevel, leading to switching of its chemical behavior. We show that under the action of ultrasound, the microstructured ionic liquid/water mixture undergoes rearrangement resulting in formation of separated phases with specific compositions and reactivities. The observed effect was successfully utilized for creation of dissipative soft microreactors formed in ionic liquid/water media during the sonication-driven water transfer. The performance of the microreactors was demonstrated using the example of controlled synthesis of small and uniform gold and palladium nanoparticles. The microsonication stage, designed and used in the present study, opened unique opportunities for direct sonochemical studies with the use of electron microscopy.

An Unusual Microdomain Factor Controls Interaction of Organic Halides with the Palladium Phase and Influences Catalytic Activity in the Mizoroki‐Heck Reaction

“…The previously reported results of extensive electron microscopy studies on IL‐based mixtures clearly showed that 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([C 4 mim][BF 4 ]) ionic liquid can serve as an excellent medium for the creation of stable liquid microdomains. [ 21,47,82 ] This distinctive feature made [C 4 mim][BF 4 ] the solvent of choice for carrying out a number of chemical transformations involving transition‐metal compounds with the aim of studying the effect of the microlevel organization of a liquid reaction mixture on the structure and catalytic activity of metallic species. In the model processes, the palladium precursor (palladium acetate) in [C 4 mim][BF 4 ] ionic liquid was reacted with aryl halide, as the common component of the organic transition‐metal‐catalyzed transformations.…”

Nanoscale Advancement Continues—From Catalysts and Reagents to Restructuring of Reaction Media

“…IL‐based microstructured mixtures have been successfully used as the reaction media in organic synthesis and catalysis, in polymerization processes, as well as in the preparation of nanomaterials [7] . Recently, the possibility of controlling the synthesis of metal particles in aqueous ionic liquid media through the use of a mechanical (ultrasound) wave ordering effect was demonstrated [8] . Nanoscale heterogeneities in ILs have been detected spectroscopically, [9] and nanostucturing of IL/water systems has been described by computational modeling [10] …”

Recent Progress of Fuel‐Driven Temporary Materials

“…The time‐dependent variety brings more opportunities to realize new functions and applications. The external energy that drives the formation of temporary materials can be from light, [ 17‐19 ] sound, [ 20‐22 ] mechanical forces, [ 23 ] or chemical fuels, etc . However, chemical fuel‐driven temporary materials are the most frequently reported among them.…”