ICAMS / Interdisciplinary Centre for Advanced Materials Simulation

Polymer Structure at Interfaces and Ion Diffusion Mechanisms

Polymer coatings are used for corrosion protection in many applications. Diffusion of ions (galvanic coupling) as well as small molecules (O2, H2O) along the metal/polymer interface and close to the interface is known to be orders of magnitude faster than through the bulk polymer. However, there is no fundamental understanding of the mechanism for diffusion and ion incorporation, and its relation to the polymer structure and composition. The objective of the present project is to develop an atomistic understanding of the interface structure of polymer/oxide contacts and of the diffusion mechanism of ions along and close to the interface as a guide for future material design. A central issue is the determination/development of a realistic model of the polymer morphology close to the interface. The complexity of the polymer structure at the interface requires a multi-scale approach.
For this purpose, the interactions at the polymer/metal-oxide interface will be studied with first principles DFT methods using characteristic fragments and functional groups of the polymer. An atomistic force-field description of these interactions will be developed. Based on this, a coarse-grained force-field will be developed, that allows to equilibrate the polymer structure at the interface and thus develop a realistic interphase structure. Using techniques developed by Nico van der Vegt (Max-Planck-Institut für Polymerforschung, Mainz) atomic details will be reinserted into the equilibrated coarse-grained structure.
The uptake of water and the incorporation of ions and their diffusion will be studied, based on the atomistic model of the polymer/oxide interface generated in the previous step. The results will be validated using SKP measurements of the ion diffusion and experimental techniques available at the Max-Planck-Institut für Eisenforschung.

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