Light‐Controlled Nucleation and Shaping of Self‐Assembling Nanocomposites

Abstract

Controlling self‐assembly of nanocomposites is a fundamental challenge with exciting implications for next‐generation advanced functional materials. Precursors for composites can be generated photochemically, but limited insight in the underlying processes has hindered precise hands‐on guidance. In this study, light‐controlled nucleation and growth is demonstrated for self‐assembling composites according to precise user‐defined designs. Carbonate is generated photochemically with UV light to steer the precipitation of nanocomposites of barium carbonate nanocrystals and amorphous silica (BaCO3/SiO2). Using a custom‐built optical setup, the self‐assembly process is controlled by optimizing the photogeneration, diffusion, reaction, and precipitation of the carbonate species, using the radius and intensity of the UV‐light irradiated area and reaction temperature. Exploiting this control, nucleation is induced and the contours and individual features of the growing composite are sculpted according to micrometer‐defined light patterns. Moreover, moving light patterns are exploited to create a constant carbonate concentration at the growth front to draw lines of nanocomposites with constant width over millimeters with micrometer precision. Light‐directed generation of local gradients opens previously unimaginable opportunities for guiding self‐assembly into functional materials.

Contraction and Expansion of Nanocomposites during Ion Exchange Reactions

“…We foresee that these insights may directly impact our ability to shape chemical compositions according to an exact design by first programming a desired shape and subsequently customizing the chemical composition. As a first step, we recently demonstrated that photogeneration of carbonate enables light-controlled nucleation and sculpting of these composites . The next step toward this ambitious goal will be to gain complete hands-on control over the self-assembly process of the nanocomposite in three dimensions, thus opening new routes toward rationally designed functional structures for catalysis, optics, and photovoltaics.…”

“…As a first step, we recently demonstrated that photogeneration of carbonate enables light-controlled nucleation and sculpting of these composites. 39 The next step toward this ambitious goal will be to gain complete hands-on control over the self-assembly process of the nanocomposite in three dimensions, thus opening new routes toward rationally designed functional structures for catalysis, optics, and photovoltaics.…”

Spatial programming of self-organizing chemical systems using sustained physicochemical gradients from reaction, diffusion and hydrodynamics

“…Changing the environmental conditions by e.g. changing the CO 2 influx, or the local availability of CO 2 via a photochemical reaction, 71 allows modulating the local gradients around the growth front, and thereby switching between different types of structures that are co-precipitating over the course of the growth process. Finally, the structures produced this way can be modified via ion-exchange reactions ( Fig.…”

Architected Metal Selenides via Sequential Cation and Anion Exchange on Self-Organizing Nanocomposites

“…In addition, local control over CO 2 concentrations using photodecarboxylation enables the steering of the self-organization process to yield metal carbonate silica nanocomposites according to exact user-defined light patterns. 22 …”

“…The extraordinary complexity of biomineralized architectures demonstrates the possibilities for organizing a limited number of simple minerals into a wide diversity of highly refined, multifunctional, three-dimensional (3D) shapes. − Inspired by biomineralization processes, many synthetic self-organization strategies have been developed to produce artificial complexly shaped 3D architectures. ,− Already, a large diversity of intricately shaped 3D forms can be formed during the bioinspired coprecipitation of metal carbonate nanocrystals (MCO 3 , with M = Ba 2+ , Sr 2+ , or Ca 2+ ) and amorphous silica (SiO 2 ) (Figure A). ,, These bioinspired nanocomposites self-organize into highly complex, yet controllable, 3D shapes such as vases, stems, helices, and coral-like forms that can be further sculpted and patterned by modulating the global reaction conditions. In addition, local control over CO 2 concentrations using photodecarboxylation enables the steering of the self-organization process to yield metal carbonate silica nanocomposites according to exact user-defined light patterns …”