DFG Priority Program SPP 1164
Nano- & Microfluidics:
Bridging the Gap between
Molecular Motion and Continuum Flow
Molecular transport and flow on one- and two-component polymer brushes
| Project Leader: | Prof. Dr. Marcus Müller Georg-August-Universität Göttingen Institut für Theoretische Physik Göttingen |
Summary
The flow of polymer liquid on brush-coated substrates and the motion of
drops driven by an external force will be studied by computer
simulations of a coarse-grained polymer model. The boundary properties
at the interface between the soft, elastically deformable substrate and
the melt of identical molecules are dominated by universal entropic
effects which are independent of the chemical structure and can
experimentally be controlled via the grafting density or chain length.
Different simulation techniques will be utilized to obtain the flow field in the vicinity of the soft substrate (slip length), the (equilibrium, advancing and receding) contact angles, and to investigate the precursor film and the stationary velocity of droplets driven by external fields. The motion of the three-phase contact line, the deformation of the soft substrate in its vicinity, and mechanisms of energy dissipation shall be investigated. Particular attention will be devoted to droplet size effects and the systematic extrapolation of the simulation results to larger drops.
Additionally, we will consider the flow in open wedges and through cylindrical channels, and the droplet motion and pinning of droplets on laterally structured substrates (chemical stripes or binary polymer brushes that exhibit microphase separation).
We aim at establishing a close connection to experiments of droplet motion on soft substrates (polymer brushes or networks) and a meso-scale, continuum description. We will provide insight into the relation between the boundary condition utilized in the continuum approach and the molecular structure. The continuum approaches help us in extrapolating from submicrometer droplets in the simulations to experimentally relevant sizes.
Different simulation techniques will be utilized to obtain the flow field in the vicinity of the soft substrate (slip length), the (equilibrium, advancing and receding) contact angles, and to investigate the precursor film and the stationary velocity of droplets driven by external fields. The motion of the three-phase contact line, the deformation of the soft substrate in its vicinity, and mechanisms of energy dissipation shall be investigated. Particular attention will be devoted to droplet size effects and the systematic extrapolation of the simulation results to larger drops.
Additionally, we will consider the flow in open wedges and through cylindrical channels, and the droplet motion and pinning of droplets on laterally structured substrates (chemical stripes or binary polymer brushes that exhibit microphase separation).
We aim at establishing a close connection to experiments of droplet motion on soft substrates (polymer brushes or networks) and a meso-scale, continuum description. We will provide insight into the relation between the boundary condition utilized in the continuum approach and the molecular structure. The continuum approaches help us in extrapolating from submicrometer droplets in the simulations to experimentally relevant sizes.