Fabrication of High Added-Value Crystalline Products and Nanostructured Materials

Crystalline materials are a key component of a vast number of high added-value products and emerging technologies. The product quality requirements of crystalline materials are increasingly stringent in order to comply with demands for more sustainable fabrication processes and enhanced functional performance of the final product.

            Fabrication processes of crystalline materials span several length scales as illustrated in Figure 1. At the smallest scale, elementary building blocks (e.g. ions, organic molecules, proteins, DNA tiles) define the chemical identity of the final product. These building blocks are assembled via reversible and non-covalent interaction forces into clusters with a specific structural identity. The efficiency for further processing and the functionality of the final product are determined by this structural identity. For example, the precise confirmation of an active pharmaceutical ingredient in a crystal lattice can have dramatic effects on the shape of the crystals to be further processed or on the bioavailability of the final product. Furthermore, emerging nanostructured materials derives their exciting functional properties, in addition to the chemical composition, from periodic or non-periodic structural features. In the final step of the fabrication process, crystalline clusters are grown to a final state while preserving the chemical and structural identity of the existing clusters. During this stage, final product properties such as the crystal size distribution evolve.

            Current fabrication processes for crystalline materials fail to meet future demands for sustainability and enhanced properties of the final product. The fundamental reason is that actuation on the scale of individual building blocks is poorly exploited and instead only macroscopic variables such as temperature, pressure, and composition are being used. These macroscopic actuators are able to influence the growth phase of the fabrication process, but offer limited flexibility to control the formation of the individual crystalline clusters.

            My long-term research goal is to drastically improve the performance of fabrication processes for crystalline materials by directing the assembly of crystalline clusters with actuation at the nano- and microscale combined with a subsequent dedicated growth phase.

            Figure 1: Multi-scale fabrication process of crystalline materials.