Controlling complex crystallization From dendrites to spherulites and beyond

This thesis investigates how complex crystal morphologies can emerge from simple inorganic systems under mild, aqueous conditions. It demonstrates that structural complexity does not require biological templates or extreme environments, but can arise from the interplay of kinetics, diffusion, additive interactions, and sequential growth.
Using carbonate- and sulfate-based systems, several strategies to control crystal morphology are developed. Small organic additives are shown to direct growth by selectively inhibiting specific crystal faces, enabling hierarchical multilayered structures. Silica enables the formation of compact, shape-controlled spherulites with tunable size, and allows growth to be paused and resumed, facilitating sequential shaping into non-classical geometries. In another system, silica can induce growth reorientation and morphological transitions, generating complex structures even outside classical biomorph-forming conditions.
Additionally, self-assembled nanocrystals are introduced as nucleation directors, allowing precise spatial and crystallographic control over sequential crystal growth. This approach enables the construction of complex, hierarchical architectures and their transformation into single-material systems through ion-exchange processes.
Across these systems, the results show that morphological complexity emerges from fundamental physical and chemical principles, including crystallographic anisotropy, diffusion-limited growth, and kinetic inhibition. The findings highlight new routes toward the rational design of inorganic materials with tailored architectures. More broadly, this work contributes to bridging crystal growth science with materials engineering, while pointing toward the need for predictive frameworks to better understand and control additive-directed crystallization.