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Coarse-grained Molecular Dynamics Simulations to Study Vapour Solvation in Polymer Brushes: On the border between polymer physics and computational science

Veldscholte, ir. Lars (2020) Coarse-grained Molecular Dynamics Simulations to Study Vapour Solvation in Polymer Brushes: On the border between polymer physics and computational science.

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Abstract:Polymer brushes, films consisting of polymers densely grafted to a surface, are of interest for a range of applications due to their intriguing behaviours in solvents. Although their behaviour in liquid solvents has been studied extensively, their behaviour in solvent vapours has not. In this work, Molecular Dynamics (MD) simulations of two different coarse-grained models of polymer brushes are employed to investigate the sorption behaviour of polymer brushes in solvent vapours. A constant pressure solvent environment was simulated using a grand-canonical Monte-Carlo (GCMC) chemostat. For polymers modelled by the Kremer-Grest (KG) model, a 2D parameter sweep of polymer self-affinity and polymer-solvent affinity was performed, after which sorption behaviour is classified by analysing density profiles. The KG brush exhibits strong swelling induced by absorption that appears to be governed by the relative affinity of polymer-solvent, to polymer with itself. Adsorption on the other hand, which presents as a layer of solvent on top of the brush, appears to be governed by polymer-solvent affinity only. A simulation of polyethylene (PE) in acetone, both modelled by the MARTINI model revealed density profiles similar to the results obtained from a KG brush with low-to-moderate polymer-solvent and polymer self-affinities. The collapse of the absorption of solvent in the brush onto a single parameter (the relative affinity) suggests that this aspect of the system's behaviour is not influenced by chain stretching entropy. The MARTINI simulation of PE in acetone confirms the KG simulations and illustrates the potential for simulating chemically different polymers and solvents.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics, 35 chemistry, 51 materials science
Programme:Chemical Engineering MSc (60437)
Link to this item:http://purl.utwente.nl/essays/83939
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