(398m) Numerical Optimization Meets Wet Chemistry in the Design of Novel Pigments

Small particles are exploited for their optical properties in a vast array of applications such as paint, inks, textiles and cosmetics. In many of these application areas, features of the particles (size, shape and topology) can be on the nanoscale, a fact which is often fundamentally important to their desirable properties. With the broad range of relevant product areas, future development of new optical materials will require an intimate understanding of this microstructure-function relationship in order to improve cost efficiency, environmental safety and sustainability. At the same time, there needs to be a shift from materials development through empirical synthetic experiments towards a “process chain” linking theoretical design to the practical realization of application-optimized particles. Making this possible are significant advances, on the one hand in computational tools which allow the inversion of optical simulation for the discovery of non-intuitive structures, and on the other, synthetic capabilities which go beyond the formation of single phase spherical or ellipsoidal particles. 

Many aspects of this new approach to colorant development have been explored in the framework of an interdisiplinary project carried out in the framework of the Erlangen-based Cluster of Excellence “Engineering of Advanced Materials”. The aim has been, on the one hand, to develop systematic and efficient theoretical screening tools for the exploration of the physically possible parameter space for nanostructured particles.  On the other hand, we have considered the practical realisation of nanostructured optical particles, in several cases having motifs directly inspired by the theoretical work. In view of potential applications, focus on scalable and tunable processes has been a particular feature of the project.

This poster will exemplify the work of the project described above for the case of particles with multifunctional visible and IR optical extinction properties, a requirement for heat reflecting windows or "cool" roof-tiles. We demonstrate how mathematical optimization techniques can take over where intuitive screening using Lorenz-Mie approaches reaches practical limitations. Furthermore, we show that the designed particle structures can be fabricated and the resulting optical properties are consistent with the original target function. This work shows how mathetical approaches could in the near future revolutionize the pigment design process.