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Concentration-induced planar-to-homeotropic anchoring transition of stiff ring polymers on hard walls

Autor(en)
Peter Poier, Sergei A. Egorov, Christos N. Likos, Ronald Blaak
Abstrakt

We study the structure and interfacial ordering of stiff ring polymers close to repulsive walls. For this purpose, we employ an anisotropic effective model in which the rings are pictured as soft, penetrable discs [P. Poier, C. N. Likos, A. J. Moreno and R. Blaak, Macromolecules, 2015, 48, 4983]. We have studied this model in the bulk and in the presence of a wall, employing Density Functional Theory and computer simulations. While the Ornstein-Zernike equation in combination with the Hypernetted Chain Approximation gives results that are in quantitative agreement with computer simulations, a simple Mean Field approximation strongly overestimates the interaction between the effective particles in the bulk. We discover that by increasing density one can induce a reorientation of the effective rings in the vicinity of a wall, which prefer to orient themselves parallel to the surface (face-on or planar) for low densities ρ and reorient orthogonal to the wall (edge-on or homeotropic) for higher values of ρ. This transition in the surface-structure can be observed in both computer simulations, as well as in an appropriate density functional theory. We trace its physical origin in the penetrable character of the rings, which allows for a reduction of the surface tension contribution due to ring-ring interactions upon the emergence of homeotropic ordering on the wall and increasing the density of the system.

Organisation(en)
Computergestützte Physik und Physik der Weichen Materie, Forschungsplattform Internationales Erwin Schrödinger Institut für Mathematik und Physik
Journal
Soft Matter
Band
12
Seiten
7983-7994
Anzahl der Seiten
12
ISSN
1744-683X
DOI
https://doi.org/10.1039/c6sm01453d
Publikationsdatum
2016
Peer-reviewed
Ja
ÖFOS 2012
103015 Kondensierte Materie
Schlagwörter
ASJC Scopus Sachgebiete
Condensed Matter Physics, Allgemeine Chemie
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/37f6d079-2e61-48fd-bf67-5959090878ed