Anisotropic particles for colloidal self-assembly

• Anisotrope Partikel für die kolloidale Selbstassemblierung

Tigges, Thomas; Möller, Martin (Thesis advisor); Walther, Andreas (Thesis advisor)

Aachen (2017)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2017

Abstract

On the road to the development of new methods to fabricate complex materials, nature has always been an inspiration for scientists. While many researchers try to imitate the products of nature’s work, in this thesis I want to focus on understanding how to builds up complex hierarchical materials. In living organisms, everything builds up from various building blocks that carry the information for their self-assembly into the final structures. For scientists it is therefore intriguing to understand such self-assembly processes experimentally on the way to realize self-assembly and self-replicating materials. Self-assembly in nature happens across all length scales, starting from the sub-nanometer scale of the lipids in a cell-membrane to the intrinsic order between all cells to form a living organism with sizes of several meters. High complexity is encountered as the entities are driven outside equilibrium through fuel consumption and are organized through feedback loops. The principles underlying the complex self-organization in nature are self-assembly processes through controlled interactions. To study self-assembly processes in general, nano- to micrometer scale anisotropic colloidal particles with designed surface features are intriguing building blocks as they can easily be studied using microscopy methods, while still being small enough to be committed to common driving forces. This work will thus present different approaches how to generate colloidal building blocks and investigate their propensity to self-assemble into switchable superstructures. We investigate: a) microcontact printing to fabricate spherical, patchy microparticles that carry a spatially confined functionality only in one patch area, b) direct 3D laser writing to fabricate anisotropic particles for depletion interaction driven self-assembly via shape recognition and c) 3D DNA origami for hierarchical self-assembly of single stranded DNA into patchy colloidal building blocks that again self-assemble to form supracolloidal fibrils. While the presented methods all aim to fabricate colloidal building blocks, they differ considerably in their propensity to self-assemble, which will be further discussed in this work.