Understanding the dynamics and flow properties of polymers, liquid crystals, and other complex fluids is a challenge due to the presence of multiple time and length scales involved. Together with Martin Kröger and Hans Christian Öttinger from ETH Zürich, we have recently proposed and successfully tested a systematic approach to thermodynamically consistent coarse-graining and multiscale simulations. In this approach, time- and length-scales are bridged with the help of projection operator methods, where we evaluate the formal expressions with iterative Monte Carlo-molecular dynamics simulations that are combined in a self-consistent manner.

Polymer physics is a classical area of soft condensed matter with enormous importance for material science and industrial applications. Due to the presence of vastly different time- and length-scales involved in their dynamics, polymers provide an important test case for coarse-graining and multiscale simulation schemes. Together with Martin Kröger and Hans Christian Öttinger from ETH Zürich, we have successfully tested our recently proposed our systematic coarse-graining approach to polymer melts with low molecular weight.

Polymer brushes are very efficient in lubricating surfaces. In collaboration with Manjesh Singh, Nic Spencer, Martin Kröger and Rosa Espinosa-Marzal, we investigate the tribological properties of model polymer brushes by nonequilibrium molecular simulations and compare the predictions to experimental results. This work has been supported by a grant from the ETH Zürich.

In magnetic suspensions, field-induced cluster formation of magnetic particles gives raise to a macroscopic magnetization as well as strongly anisotropic mechanical and viscous properties. We are using computer simulations to study the flow- and field-induced structure of magnetic fluids as well as their viscous behavior and compare those findings to experimental results. The possibility to manipulate fluid properties simply by changing an externally applied magnetic field make these fluids very attractive for various applications.

The phase transition from the isotropic to an orientationally ordered state has led to variety of practical applications of liquid crystals and has triggered many theoretical and simulation studies. We are working on the modeling and simulation of the nonequilibrium phase transition in liquid crystals under flow. Starting from a molecular model of interacting mesogens, we derived an augmented Landau-de Gennes free energy from thermodynamic integration in a generalized canonical ensemble. This project is supported by a EU Career Integration grant.

The flow properties of supercooled liquids are still not well understood despite their enormous importance in processing and other practical applications of diverse soft amorphous systems. We use the inherent structure approach together with nonequilibrium statistical thermodynamics as a guiding principle to formulate building blocks for constitutive models for supercooled liquids. This project is done together with Ingo Füreder and is supported by a grant from the Swiss National Science Foundation.

The aim of this project is to characterize the microstructure and mechanical properties of interfaces stabilized by multi-block copolymers, using a multiscale multidisciplinary approach, which integrates state of the art computational methods with surface rheological experiments, and experimental interfacial structure evaluation. This project is carried out in collaboration with Leonard Sagis, Martin Kröger and Peter Fischer and supported by a grant from the Swiss National Science Foundation.