Designing Complex Tapestries with Photography-Inspired Manipulation of Self-Organized Thin-Films

Thin-films patterned with complex motifs are of fundamental interest because of their advanced optical, mechanical and electronic properties, but fabrication of these materials remains challenging. Self-organization strategies, such as immersion controlled reaction-diffusion patterning, have shown great potential for production of patterned thin-films. However, the autonomous nature of such processes limits controllable pattern customizability and complexity. Here, it is demonstrated that photography inspired manipulation processes can overcome this limitation to create highly-complex tapestries of micropatterned films (MPF's). Inspired by classical photographic processes, MPF's are developed, bleached, exposed, fixed, and contoured into user-defined shapes and photographic toning reactions are used to convert the chemical composition MPF's, while preserving the original stripe patterns. By applying principles of composite photography, highly complex tapestries composed of multiple MPF layers are designed, where each layer can be individually manipulated into a specific shape and composition. By overcoming fundamental limitations, this synergistic approach broadens the design possibilities of reaction-diffusion processes, furthering the potential of self-organization strategies for the development of complex materials.

Light-controlled morphological development of self-organizing bioinspired nanocomposites

Nature's intricate biominerals inspire fundamental questions on self-organization and guide innovations towards functional materials. While advances in synthetic self-organization have enabled many levels of control, generating complex shapes remains difficult. Specifically, controlling morphologies during formation at the single micro/nanostructure level is the key challenge. Here, we steer the self-organization of barium carbonate nanocrystals and amorphous silica into complex nanocomposite morphologies by photogeneration of carbon dioxide (CO2) under ultraviolet (UV) light. Using modulations in the UV light intensity, we select the growth mode of the self-organization process inwards or outwards to form helical and coral-like morphologies respectively. The spatiotemporal control over CO2 photogeneration allows formation of different morphologies on pre-assigned locations, switching between different growth modes-to form for instance a coral on top of a helix or vice versa, and subtle sculpting and patterning of the nanocomposites during formation. These findings advance the understanding of these versatile self-organization processes and offer new prospects for tailored designs of functional materials using photochemically driven self-organization.

Light-driven nucleation, growth, and patterning of biorelevant crystals using resonant near-infrared laser heating

Spatiotemporal control over crystal nucleation and growth is of fundamental interest for understanding how organisms assemble high-performance biominerals, and holds relevance for manufacturing of functional materials. Many methods have been developed towards static or global control, however gaining simultaneously dynamic and local control over crystallization remains challenging. Here, we show spatiotemporal control over crystallization of retrograde (inverse) soluble compounds induced by locally heating water using near-infrared (NIR) laser light. We modulate the NIR light intensity to start, steer, and stop crystallization of calcium carbonate and laser-write with micrometer precision. Tailoring the crystallization conditions overcomes the inherently stochastic crystallization behavior and enables positioning single crystals of vaterite, calcite, and aragonite. We demonstrate straightforward extension of these principles toward other biorelevant compounds by patterning barium-, strontium-, and calcium carbonate, as well as strontium sulfate and calcium phosphate. Since many important compounds exhibit retrograde solubility behavior, NIR-induced heating may enable light-controlled crystallization with precise spatiotemporal control.

Light-Controlled Nucleation and Shaping of Self-Assembling Nanocomposites

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.