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.

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The Netherlands Organisation for Scientific Research (NWO)
Adv. Mater.
Self-Organizing Matter

Bistervels, M., Kamp, M., Schoenmakers, H., Brouwer, F., & Noorduin, W. (2022). Light‐Controlled Nucleation and Shaping of Self‐Assembling Nanocomposites. Adv. Mater., 34(5), 2107843: 1–7. doi:10.1002/adma.202107843