Light-Modulated Intermittent Wave Groups in a Diffusively Fed Reactive Gel

Pressure and Light Multi-Physics Fields Comodulate the Multi-Length Scales of Chemical Wave Propagation in Diffusion-Fed Gels

During plant growth, the combined effects of multi-physics fields such as light, temperature, and material concentration create a complex multi-length scales phenomenon. However, the mechanism of multi-physical field interactions on biological multi-length scales has not been thoroughly investigated. In this paper, an open diffusion-fed system is constructed by coupling gels with a Belousov-Zhabotinsky (BZ) chemical reaction system. The multi-length scales propagation of chemical waves in the gel system under the combined effect of multi-physical fields such as light (I) and pressure (ΔP) is investigated. It is found that when 85 Pa ≤ ΔP ≤ 100 Pa or 200 μW·cm^-2 ≤ I ≤ 300 μW·cm^-2, the complexity of the multi-length scales periodic structure of chemical waves shows a nonlinear change with increasing light intensity or pressure. Beyond this range, the complexity of the chemical wave multi-length scales periodic structure decreases linearly on enhancing the light intensity or increasing the pressure.

Modulation of spatiotemporal dynamics in the bromate–sulfite–ferrocyanide reaction system by visible light

We have carried out the first systematic study of the effects of visible light on the homogenous dynamics in the bromate–sulfite–ferrocyanide (BSF) reaction. Under flow conditions, the reaction system displayed photoinduction and photoinhibition behavior, and the oscillatory period decreased with the increase of light intensity, which is due to the fact that light irradiation mainly enhanced the negative process and affected the positive feedback. The light effect on positive and negative feedback is studied by analyzing the period length of pH increasing and decreasing in detail. With the increase of light intensity, the period length of pH increasing decreases monotonically, while the period length of pH decreasing changes nonmonotonically. These results suggest that light could be used as a powerful tool to control homogenous dynamics. Results obtained from numerical simulations are in good agreement with experimental data.

The BSF reaction system displayed photoinduction and photoinhibition behavior under flow conditions. The oscillatory period decreased as the light irradiation mainly enhanced the negative process and affected the positive feedback.

Exploration of Light-Controlled Chemical Behavior and Mechanism in a Macrocyclic Copper Complex Catalyst–Acetone–Glucose–Bromate–Sulfuric Acid Oscillation System

In this paper, the effect of ultraviolet light on the [CuL](ClO4)2–glucose (Glu)–acetone (Act)–sodium bromate (NaBrO3)–sulfuric acid (H2SO4) oscillation system was studied. The reaction mechanism and Oregonator model were established to verify the mechanism. Comparison of the bromide ion electrode–platinum electrode correlation diagrams with and without ultraviolet light reveals a nontracking phenomenon in the bromide ion electrode–platinum electrode correlation diagram under illumination, indicating that the illumination will affect the changes in the bromide ion concentration in the system. During the process, as UV intensity increases, the concentration of bromide ions in the system increases, and bromide ions can inhibit chemical oscillations, resulting in a decrease in the amplitude of chemical oscillations, further verifying that the proposed mechanism is reasonable.

Under Diffusion Control: from Structuring Matter to Directional Motion

Self-organization in synthetic chemical systems is quickly developing into a powerful strategy for designing new functional materials. As self-organization requires the system to exist far from thermodynamic equilibrium, chemists have begun to go beyond the classical equilibrium self-assembly that is often applied in bottom-up supramolecular synthesis, and to learn about the surprising and unpredicted emergent properties of chemical systems that are characterized by a higher level of complexity and extended reactivity networks. The present review focuses on self-organization in reaction-diffusion systems. Selected examples show how the emergence of complex morphogenesis is feasible in synthetic systems leading to hierarchically and nanostructured matter. Starting from well-investigated oscillating reactions, recent developments extend diffusion-limited reactivity to supramolecular systems. The concept of dynamic instability is introduced and illustrated as an additional tool for the design of smart materials and actuators, with emphasis on the realization of motion even at the macroscopic scale. The formation of spatio-temporal patterns along diffusive chemical gradients is exploited as the main channel to realize symmetry breaking and therefore anisotropic and directional mechanical transformations. Finally, the interaction between external perturbations and chemical gradients is explored to give mechanistic insights in the design of materials responsive to external stimuli.

Fuel-Driven Dissipative Self-Assembly of a Supra-Amphiphile in Batch Reactor

Dissipative self-assembly is an intriguing but challenging research topic in chemistry, materials science, physics, and biology because most functional self-assembly in nature, such as the organization and operation of cells, is actually an out-of-equilibrium system driven by energy dissipation. In this article, we successfully fabricated an I₂-responsive supra-amphiphile by a PEGylated poly(amino acid) and realize its dissipative self-assembly in batch reactor by coupling it with the redox reaction between NaIO₃ and thiourea, in which I₂ is an intermediate product. The formation and dissipative self-assembly of the supra-amphiphile can be repeatedly initiated by adding the mixture of NaIO₃ and thiourea, which herein acts as "chemical fuel", while the lifetime of the transient nanostructures formed by the dissipative self-assembly is easily tuned by altering thiourea concentration in the "chemical fuel". Furthermore, as an application demo, the dissipative self-assembly of the supra-amphiphile is examined to control dispersion of multiwalled carbon nanotubes in water, exhibiting a good performance of organic pollutant removal.