Open Positions and Thesis Topics
- Studies of patchy/Janus particles self-assembly (suitable for someone with background in chemistry, physics)
- Studies of the optical properties of single plasmonic particles (suitable for someone with a background in physics/applied physics/materials science)
If you have specific experience in any of these areas we would be very interested to discuss a possible position in our group. We welcome speculative applications provided a clear academic and preferably research background in related fields (chemistry, materials science, nanotechnology, chemical engineering etc.) exist. If you are interested in interdisciplinary research combining colloidal synthesis of complex multifunctional nanoparticulate materials, morphological and functional characterisation as well as exploitation in application-relevant systems please send a resume (with publication list, if applicable) and a list of references to robin.klupp.taylor (at) lfg.fau.de
Contact: Robin Klupp Taylor
The nanostructured particles research group has developed a simple and scalable process to produce metal patches on core particles. Due to the nature of the processes, the patches have a size distribution and not all core particles get coated (see left image below). In order to further optimize the process to produce patchy particles with desirable properties quantitative insight into the patchy dispersity is required. In this project image analysis will be developed for this purpose. The project involves little or no practical labwork and is particularly suitable for students with some programming experience.
What we want: Image analysis codes to determine core size distribution, patch yield (fraction of particles with patch), thickness and coverage distribution
Starting point: real and simulated images of patchy particles and a code to determine which particles have a patch (see right image below)
Project objectives:
- Develop code able to segment and measure the core particle and patches.
- Develop an experimental protocol for obtaining well dispersed patchy particles, automatically acquiring images on the SEM and analysing them for patch yield and coverage
Tools:
- ImageJ
- Python
- POVRay
- Matlab
- Scanning electron microscopy
- Analytical (ultra)centrifugation
Contact: Robin Klupp Taylor
The starting point of this project will be a simple and robust process based on electrophoretic deposition (see Figure below) developed in the group. This process deposits flake-like particles (e.g. commercial mica powder) in an out-of-plane arrangement. In this project, the possibility to arrange flakes in this way will be exploited in order to partially coat the flakes i.e. produce “Janus flakes”. This will be achieved by masking the part of the flakes closest to the substrate with a suitable polymer, followed by coating of the exposed part of the flakes. Once the flakes are released, such partial coating could be used to give the flakes amphiphilic properties, enable catalytic self-propulsion or introduce an unusual optical or magnetic properties.
Project objective: Demonstrate that the out-of-plane oriented flakes can be further processed to produce novel functional particulate materials
- Re-commission previously established electrophoresis setup
- Establish desirable coating chemistry (polymer or inorganic material) on suspended flakes
- Establish partial flake masking strategy (already in literature for spherical particles)
- Show that coating chemistry can be applied to exposed parts of flakes
- Release flakes and characterise properties.
Tools:
- Electrophoretic deposition
- Particle coating methods (wet chemical synthesis)
- Thin film coating methods (spin-coating etc)
- Particle characterisation (DLS, analytical centrifugation)
- Optical microscopy and Scanning electron microscopy
Figure 1: Electron microscopy micrographs of different anisotropic particles (RKT)
Anisotropic particles are the focus of the research interest in the Nanostructured Particles Group. In recent years, we have developed various methods to synthesize so-called patchy particles (see Figure 1, first, third and fifth part). These particles consist of a dieletric core particle, partially coated with another material, in our case noble metals such as silver. Due to their size in the nm-range, the metal patches exhibit a plasmon resonance resulting in distinctly colored samples depending on the shape and size of the patches (see Figure 2).
Figure 2: Photograph of silver on silica patchy particles with increasing coverage (AV)
Over the last years, we have developed a highly tunable, continuous flow synthesis. This allows us to easily scale-up the volume of patchy particle products to several grams of product. This is a prerequisite for a step-change towards applications of patchy particles. Due to the wide tunability of the optical properties, the silver patchy particle system is highly interesting for color applications as in pigments.
Objective
One objective of the project is to obtain paint films of patchy particles. Due to the dichroic effect of the plasmonic particles, several parameters as core particle size, film thickness and particle concentration have to be adjusted to generate the most promising color effect.
In a further step, the synthesis volume should be scaled up to produce grams of powder material, which can then be incorporated in or added to polymer powder for 3D printing of plasmonic particles colored structures.