The program division “Structure Formation” investigates how molecules, polymers and colloidal particles join to form materials. It studies fundamental processes of structure formation and applies them to prepare new materials from liquid precursors.
We study how the properties of composite and hybrid materials depend on their microstructures and how to change them. To this end, we systematically vary size, geometry, chemical composition, and arrangement of the materials’ constituents. We observe how microstructure and interfaces form and affect material properties to create transparent conductive layers of metal nanoparticles for electronics, composites of conductive polymers with optically active particles for sensors and supraparticles that contain optically active nanoparticles, for example. We see particles as the basis of future “active nanocomposites” that can interface with electronics and change their properties whenever required.
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Flexible and printed electronics require new material. Here, we focus on optically transparent materials for the electronics of the future. This BMBF-funded research project, a part of the NanoMatFutur initiative, uses nanoparticles with defined shapes and arrangements inside polymers to make transparent electrodes for touch-screen display or solar cells, for example. Chemists, material scientists and an engineer collaborate very closely in a team to create new materials that can be processed with well-established wet coating and printing techniques.
Nanoparticles that are trapped in emulsion droplets react to their confinement depending on the surfactant. Some of them form beautifully ordered “supraparticles”, fully defined structures that remind of noble gas condensates or small metal clusters. We study how nanoparticles interact with each other and liquid-liquid interfaces in this DFG-funded project. Tanja Schilling at the University of Luxembourg use simulations to predict and understand structure formation, we explore it experimentally.References
Small particles play a large role in modern steel. The Dilliger Hütte, a steel mill in Saarland, collaborates with us to analyse these particles using methods that we developed for colloidal particles and that are not usually employed in metallography.
Connecting biological objects with electronics requires soft electrical contacts. To that end, we explore the fabrication of micro-fibrillar adhesion devices from electrically conductive materials. Detailed characterization of these devices reveals the relationship between adhesion properties and electrical resistivity. Their application as electrically tunable devices is also explored.
Embedded nanoparticles lend today’s nanocomposites useful properties such as color, strength, or a high refractive index. Their arrangement affects these properties but does not usually change after material synthesis because the particles are bound too strongly in the matrix. We investigate nanocomposites in which metal nanoparticles can move and reorganize in reponse to a stimulus. Thus, the color or other properties of the composite change. In this project, we synthesize model particles and study how they can be embedded such that they retain a certain mobility.
This interdisciplinary project aims at the scalable growth of mesenchymal stem cells using new carrier materials for proliferation. In collaboration with cell biologists, biochemists, chemists and material scientists, we modify surfaces of microspheres so as to increase cell adhesion, help cell proliferation and allow for their easy detachment from these microbeads. The materials-oriented part of the project involves surface characterization of beads which are about 100 µm in size followed by their surface modification such as by polymer graft, plasma activation, and changing surface roughness and surface charges. The project is a part of “European territorial cooperation” INTERREG.
Field-flow fractionation can fractionate particles after size, but it is often plagued by losses of particles due to adsorption and agglomeration. This AiF-ZIMM-project (supported by the BMWi) aims to reduce such losses and make FFF suitable as a standard technique for nanoparticle detection in products, the environment, and food.
Digital imagers for medical X-ray are based on ceramic layers. This project is a BMBF-funded effort, coordinated by Siemens, to build X-ray imagers based on a new material that contains conductive polymers and inorganic particles. The particles absorb and convert X-ray photons, the polymer transports the charges to electrodes. The Structure Formation Group is mainly concerned with the analysis of the particle-polymer composites’ structures, its origins in fabrication, and its effect on detector performance.
Mixtures of nanoparticles and proteins tend to form hybrid agglomerates. We are interested in the agglomeration mechanisms and the structure of such agglomerates to better understand their role in medicine, ecology, and biomaterials.
Formation Mechanism for Stable Hybrid Clusters of Proteins and Nanoparticles (ACS)
ACS NANO, DOI: 10.1021/acsnano.5b01043
Interactions drives particles to agglomerate, mobility allows them to follow this drive. We use flow setups and synchrotron Small-Angle X-ray Scattering (SAXS) to study early stages of agglomeration. The results help us to better understand the formation of composites, crystallization mechanisms, and biomineralization phenomena.