Under Diffusion Control: from Structuring Matter to Directional Motion

Abstract

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.

Mechanical Control of Periodic Precipitation in Stretchable Gels to Retrieve Information on Elastic Deformation and for the Complex Patterning of Matter

“…Material design using phenomena out of equilibrium, diffusion, and chemical patterns is currently a popular trend in material science since nonequilibrium (NE) phenomena give rise to emergent properties and higher levels of complexity . In a sense, materials formed during NE processes carry the information of the chemical pathway of the NE phenomenon and therefore, have sensing and environment tracking abilities.…”

“…Finally, an example of using complex patterning to deposit polypyrrole by using precipitation patterns is shown as a template.Material design using phenomena out of equilibrium, diffusion, and chemical patterns is currently a popular trend in material science since nonequilibrium (NE) phenomena give rise to emergent properties and higher levels of complexity. [1][2][3] In a sense, materials formed during NE processes carry the Adv.…”

Modeling Diffusion in Functional Materials: From Density Functional Theory to Artificial Intelligence

“…Particle movement that is classified as diffusion appears in a wide range of solid state materials, including metals, ceramics, polymers, and biomaterials . Recently, the interest extended to areas related to functionalized materials such as nanoscale materials for electronics, ionic transport in batteries and supercapacitors, self‐organization of synthetic materials and nanoparticle diffusion for cellular activity, drug delivery among others. Therefore, a basic understanding of diffusion is important to understand various processes in materials science that have an impact on processing and functionality, including nucleation, crystal growth, sintering, hardening, alloying, phase transformation, oxidation, plastic flow, and fracture.…”

Hierarchical 3D Patterns with Dynamic Wrinkles Produced by a Photocontrolled Diels–Alder Reaction on the Surface

“…[3,11,[14][15][16] In contrast to these traditional top-down approaches, however, the formation of surface patterns in nature is usually spontaneous and selforganized and often involves the transfer of matter or energy and the interaction of compressive stress. [17][18][19][20][21] Although natural bottom-up approaches are facile, low-cost, straightforward processes, the surface structures are difficult to be accurately controlled. Combining the advantages of these two methods to prepare hierarchical surface patterns has attracted extensive interest.…”

“…Although complex structured surfaces can be fabricated by photolithography or nanoimprinting technologies, which provide precise control, almost all the conventional patterning technologies involve complex processes and are time‐consuming . In contrast to these traditional top‐down approaches, however, the formation of surface patterns in nature is usually spontaneous and self‐organized and often involves the transfer of matter or energy and the interaction of compressive stress . Although natural bottom‐up approaches are facile, low‐cost, straightforward processes, the surface structures are difficult to be accurately controlled.…”