Directing Sequential Self-Organization with Self-Assembled Nanocrystals

Sequential self-organization can be used to design the hierarchy and complexity of materials beyond what is possible with single-step synthesis. However, such sequential approaches introduce additional challenges in maintaining control over the process. To guide the position and orientation of newly nucleated material, we propose the use of self-assembled nanocrystals (SANCs). We test the potential of SANCs in BaCO3|SiO2 nanocomposites, also termed silica biomorphs, to direct the formation of nascent microscopic crystals. We find that SANCs can direct the location and crystallographic orientation of microcrystals at the nucleation stage, while the material, polymorph, and growth behavior of the crystal can be tuned largely independently. Using ion exchange reactions, we show that structures can be unified into a single material of interest in subsequent steps. This level of control over material position, orientation, and chemical composition allows for the retrosynthetic design of complex hierarchical structures.