Thesis Offers (B.Sc., M.Sc. and MAP miniproject)

The institute has the capacity to support a large number of Bachelor’s and Master’s projects in addition to MAP miniprojects. Below you can find some of the currently available topics. However, this list is not exhaustive and students should contact the individual research scientists who cover their topic of interest regarding potential project topics.

We are looking for highly motivated Bachelor’s and Master’s students to carry out projects in our group. If you find our work interesting and would like to know more about these opportunities then please contact Prof. Robin Klupp Taylor  or the respective doctoral researchers in the group. Here are some specific open topics:

Kontakt: Andreas Völkl

In diesem Projekt werden Flake-förmige Siliziumdioxidpartikel als Kernpartikel für die Synthese definierter, kreisförmiger Silberbeschichtungen, sogenannter Patches, verwendet, die einstellbare optische Eigenschaften vom visuellen bis zum infraroten Licht einbringen. Dies eröffnet mögliche Anwendungen für diese Partikel als (verbesserte) Effektpigmente, Photokatalysatoren, partikelbasierte Laser und viele andere Anwendungen.

Patches auf Flakes wachsen typischerweise mit einer dendritischen Morphologie und nicht in einer wohldefinierten kreisförmigen Weise. Mit den jüngsten Entwicklungen in unserer Gruppe ist dies jedoch machbar geworden.

In der ersten Phase Ihres Projekts werden Sie die SiO2-Flakes mit verschiedenen Methoden wie BET, SEM und Pyknometrie charakterisieren und Gold-Nanopartikel (~4nm) synthetisieren. Diese AuNPs werden dann als Ausgangspunkt für das Wachstum von Silber-Patches auf den SiO2-Flakes verwendet. Da die Goldpartikel eine Ostwald-Reifung durchlaufen, müssen Sie deren Größe spektroskopisch überwachen, um die Flakes quantitativ mit unterschiedlicher Anzahl von Goldpartikeln, d.h. unterschiedlichen Seeding-Dichten, zu besetzen.

In der zweiten Phase werden Sie Silber-Patches mit einer Tollens-ähnlichen Redoxreaktion in unserem kontinuierlichen Reaktor synthetisieren. Mittels UV-VIS-Spektroskopie und REM-Bildern untersuchen Sie die Auswirkungen verschiedener Parameter wie Seeding-Dichte, Kernpartikelkonzentration oder Silberkonzentration auf die resultierenden Patches und versuchen, einen Zusammenhang zwischen diesen Parametern und der Patch-Größenverteilung zu ermitteln. Zusätzlich werden Sie die Produktion für die Abscheidung von Beschichtungen für Pigmenttests hochskalieren, wobei Sie spezifische Ausrichtungen der Flakes durch elektrophoretische Deposition (EPD) untersuchen.

Zusammengefasst beinhaltet das Projekt folgende Aufgaben:

  • Verschiede Charakterisierungsmethoden wie BET, SEM, He-Pyknometrie, UV-VIS Spectroscopie, etc.
  • Synthese von Gold-Nanopartikeln und Silber-Patches mit Batch und kontinuierlichen Prozessen
  • Quantifizierbares, kontinuierliches Seeding der Flake-förmigen SiO2-Partikel
  • Systematische Parameterstudien am Seeding- und am Patch-Wachstumsprozess
  • Datenanalyse und Erstellung von parameterabhängigen Eigenschaftsverteilungen
  • Scale-Up-Produktion und Abscheidung (mit EPD) für Pigmenttests

Was Sie anwenden und lernen werden:

  • Allgemeine Labortechniken
  • Synthese von Gold- und Silber-Nanostrukturen
  • Grenzflächenverfahrenstechnische Methoden im Zusammenhang mit Partikeln
  • Charakterisierungsmethoden und -geräte für Partikel und Oberflächen
  • Methoden aus der Partikeltechnologie

Links oben: Flake-förmige Partikel, Links unten: SiO2-Flakes mit dendritischen Silberbeschichtungen, Rechts: UV-VIS-NIR-Spektren, die die einstellbaren optischen Eigenschaften von sphärischen Patchy Particles zeigen.

Contact: Andreas Völkl

In this project, flake-like silica particles will be used as core particles for the synthesis of well-defined, circular silver coatings, so-called patches that introduce tunable optical properties ranging from visual to infrared light. This opens possible applications for these particles as (improved) effect pigments, photocatalysts, particle-based lasers and many other applications.

Patches on flakes typically grow with a dendritic morphology and not in a well-defined circular manner. However, with recent developments in our group this has become feasible.

In the first phase of your project, you will characterize the silica flakes using several different methods, such as BET, SEM and pycnometry and synthesize gold nanoparticles (~4nm). These AuNPs are then used as starting points for the growth of silver patches on the silica flakes. Since the gold particles undergo Ostwald ripening, you will need to monitor their size spectroscopically in order to quantifiably seed the flakes with different numbers of gold particles, i.e. different seeding densities.

In the second phase, you will grow silver patches with a Tollens-like redox reaction using our continuous flow reactor. By using UV-VIS spectroscopy and SEM imaging, you will investigate the effects of several parameters such as seeding density, core concentration or silver concentration on the resulting patches and try to determine a relationship between these parameters and the patch size distribution. Additionally, you will scale up the production in order to deposit the particles for pigment testing, exploring specific flake alignments by electrophoretic deposition (EPD).

In summary, the project will involve the following tasks:

  • Several characterization methods such as BET, SEM, He-Pycnometry, UV-VIS spectroscopy, etc.
  • Synthesis of gold nanoparticles and silver patches using batch and continuous processes
  • Quantifiable continuous flow seeding of flake-like silica particles
  • Systematic parameter studies for both the seeding and patch-growth processes
  • Data evaluation and creation of parameter dependent property distributions
  • Scaled-up production and deposition (by EPD) for pigment test

What you will learn and apply:

  • General laboratory techniques
  • Chemical synthesis of gold and silver nano-structures
  • Interface-engineering techniques related to particles
  • Characterisation methods and devices for particles and surfaces
  • Methodologies from particle technology

Top left: flake-like particles, Bottom left: SiO2-flakes with dendritic silver patches, Right: UV-VIS-NIR spectra showing tunability of optical properties of silver patches on spherical core particles

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)

Left: A typical SEM image of silver-silica patchy particles. Right: The same image following automatic processing to remove the uncoated silica particles

Project objectives:

  1. Develop code able to segment and measure the core particle and patches.
  2. 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.

Left: Electrophoretic process developed in the Nanostructured Particles Research Group to deposit flake-like particles in an out-of-plane orientation. Middle: coating produced when inert counter electrode are used. Right: coating produced when corrosion-susceptible counter electrode is used

Project objective: Demonstrate that the out-of-plane oriented flakes can be further processed to produce novel functional particulate materials

  1. Re-commission previously established electrophoresis setup
  2. Establish desirable coating chemistry (polymer or inorganic material) on suspended flakes
  3. Establish partial flake masking strategy (already in literature for spherical particles)
  4. Show that coating chemistry can be applied to exposed parts of flakes
  5. 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