(3cj) 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.