Formation of Metal-Polymer Nanocomposites by Plasma-Based Deposition Methods: Kinetic Monte Carlo and Molecular Dynamics Simulations
In this thesis, the formation of metal-polymer nanocomposites is studied by means of kinetic Monte Carlo (KMC) and molecular dynamics (MD) simulations. The KMC simulations are used to investigate the growth of metallic nanocolumns in a polymer host matrix during co-deposition of metal and polymer. The simulation model is an extended version of a previous model by Rosenthal et al. (J. Appl. Phys. 114, 044305 (2013)) to study nanocolumnar growth. The main modification is an implementation of a process to account for the creation of defects in the surface of the polymer, which is a side effect of the sputter deposition. The primary effect of the occurrence of surface defects is an increased amount of trapped metal clusters. It is the goal of this work to determine how this affects the formation of nanocolumns, which requires that initially spherically clusters reach a critical size. The experimental scenario considered in the other part of this work is the formation of a thin metal film on a polymer substrate during sputter deposition. In order to investigate this process, a Langevin-based MD simulation model is developed, which allows one to reproduce the behavior on experimentally relevant time scales by performing the simulations with large values of the deposition rate and the diffusion coefficients of metal atoms. Unlike conventional MD simulations of processes on a surface, which include an atomistic treatment of all involved particles, the atomistic description in this model is restricted to the deposited metal atoms; the polymer substrate, however, is modeled as a continuum in which the metal atoms perform random walks. In a first study, the time evolution of the morphology of a gold film is investigated for various different simulation parameters. As the comparison with experimental data displays good agreement, another study is also performed for the deposition of silver and copper.
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