Are you a highly motivated physicist with a strong interest in soft active matter and statistical mechanics? We are seeking an excellent and ambitious PhD candidate to carry out interdisciplinary research on mechanical properties of active polymer-like matter which combines experiments and simulations.

A grand challenge in active matter physics is to understand the beautiful yet complex collective phenomena emerging in large social assemblies, such as in ant rafts, fish schools, bird flocks, human crowds, and swarms of robots. The interplay between self-drive (activity) and interactions of constituents lead to novel collective properties with no counterparts in equilibrium systems. Despite encouraging theoretical advances, understanding the emergent collective properties of realistic active systems beyond toy models remains challenging. For instance, some types of worms and ants with flexible bodies form entangled aggregates that cannot be explained without invoking their internal dynamics.

Here, we propose a joint experimental-theoretical research project that aims at understanding this novel aspect of active matter by addressing the following question:

What novel mechanical properties emerge from the interplay between activity, internal dynamics, and topological entanglements in dense active polymer-like matter?

This project will be carried out in a collaborative setting under joint supervision of Dr. Sara Jabbari-Farouji and Dr. Antoine Deblais at the Institute of Physics (IoP), at the University of Amsterdam, comprised of an exciting team of researchers with a strong emphasis on collaboration. Building on computational and experimental expertise in our groups, you will combine coarse-grained molecular dynamics simulations with rheology of worms to uncover the effect of activity on the mechanical properties of entangled active polymer-like matter.

Contacts: Dr. Sara Jabbari-Farouji, s.jabbarifarouji@uva.nl & Dr. Antoine Deblais, a.deblais@uva.nl

Are you a highly motivated physicist, physical-chemist, or chemists with a strong interest in interdisciplinary research? We are seeking an excellent and ambitious PhD candidate to carry out fundamental research on micro-controlled hydrated crystal growth combined with optical microspectroscopy techniques.

Hydrated crystals – crystals with water incorporated into the crystalline structures of certain salts – are an important class of materials which have shown surprisingly new and exciting behaviors. They constitute a new field of study, both for their technological and fundamental interests. First, these crystals are promising materials as thermochemical and phase change materials for thermal energy storage, where the release or incorporation of water in the lattice is accompanied by heat release or storage. These crystals therefore form a promising solution to climatize buildings and reutilize waste heat from industrial processes. Second, hydrated salts are not only abundant and ubiquitous on the surface of the Earth but are also present on Mars providing vital information on the hydrogeologic history of other planets.

Hydrated crystals exhibit intriguing fundamentally novel structural and optical properties at the microscale, including structural colors and uncommon mechanical properties during hydration/dehydration. These properties have largely remained unexplored and the role of the stoichiometry of water in the crystalline structure is poorly understood. The main challenge lies in the metastable nature of these crystals: many properties are transient and only observable during the water uptake or release. At the same time, limited control over the local precursor concentration, temperature, and humidity hinders systematic investigation of their growth and transition dynamics.

In this project, you will combine micro-engineered reaction chambers and in-situ optical spectroscopy to unravel the unconventional properties of growth and dissolution of hydrated crystals.

Merging fully controlled microfluidic crystal growth with in-situ optical spectroscopy offers tantalizing prospects: Can the transient crystal properties be captured in a meta-stable state to study them in-situ? What is the physical mechanism underlying the structural colors at the single-crystal level? How do crystals grow in confined geometries, and how do neighboring crystal domains interact during growth?Addressing these fundamental research questions will lead to completely new insights in the field of crystal growth and requires the development of a novel platform for in-situ microfluidic single crystal growth. Using these methods, we will be able to link the microscale properties of the hydrated crystals to their thermochemical behaviour, i.e. producing heat during the hydration and storing heat during dehydration reaction in a sustainable manner.

This project will be carried out in a collaborative setting between two research groups of the Van der Waals-Zeeman Institute (WZI), comprised of an exciting team of researchers with a strong emphasis on collaboration.