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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 40: Polymer and Molecular Dynamics, Friction and Rheology

CPP 40.1: Vortrag

Dienstag, 17. März 2020, 10:45–11:00, ZEU 255

Exploring the Properties of Ionomers Through the Use of Coarse Grained Molecular Dynamic Simulations — •Nicholas Michelarakis¹, Konstantinos Gkagkas², and Frauke Gräter¹ — ¹Heidelberg Institute for Theoretical Studies, Heidelberg, Germany — ²Toyota Motor Europe NV/SA, Zaventem, Belgium

The mechanical and structural properties of the Nafion membrane in the core of a Proton Exchange Membrane Fuel Cell (PEMFC) are controlled by the molecular interactions within the Nafion molecules and with the dispersion solvent. The effect of the dispersion solvent on the Nafion membrane assembly process, and on the final Nafion membrane properties (structural morphology, water/solvent content, ion exchange capacity, membrane stability), remains an area of intense study. Here we present a non-equilibrium Coarse Grained Molecular Dynamics method, based on the MARTINI force field, for calculating the dynamic shear viscosity of the Nafion 'ink' used in PEMFC membrane printing; a trait closely correlated to the properties of the final Nafion membrane. In this method, two stationary walls are introduced in the simulation box. A pulling force along the z-axis is then applied to the bottom wall allowing for the simulation of a Couette flow. Using water as an initial test-case we demonstrate that this method has the ability to accurately predict the dynamic shear viscosity of this solvent. This is subsequently extended to a collection of other solvents and Nafion solutions, simulated under PEMFC printing conditions, indicating that this approach has the ability to recapitulate the dynamic viscosity values calculated experimentally.