Orientational ordering transitions of semiflexible polymers in thin films: A Monte Carlo simulation
2011; American Physical Society; Volume: 84; Issue: 4 Linguagem: Inglês
10.1103/physreve.84.041810
ISSN1550-2376
AutoresВ. А. Иванов, A. S. Rodionova, E. A. An, J. A. Martemyanova, Mikhail Stukan, Marcus Müller, Wolfgang Paul, Kurt Binder,
Tópico(s)Liquid Crystal Research Advancements
ResumoAthermal solutions (from dilute to concentrated) of semiflexible macromolecules confined in a film of thickness $D$ between two hard walls are studied by means of grand-canonical lattice Monte Carlo simulation using the bond fluctuation model. This system exhibits two phase transitions as a function of the thickness of the film and polymer volume fraction. One of them is the bulk isotropic-nematic first-order transition, which ends in a critical point on decreasing the film thickness. The chemical potential at this transition decreases with decreasing film thickness (``capillary nematization''). The other transition is a continuous (or very weakly first-order) transition in the layers adjacent to the hard planar walls from the disordered phase, where the bond vectors of the macromolecules show local ordering (i.e., ``preferential orientation'' along the $x$ or $y$ axes of the simple cubic lattice, but no long-range orientational order occurs), to a quasi-two-dimensional nematic phase (with the director at each wall being oriented along either the $x$ or $y$ axis), while the bulk of the film is still disordered. When the chemical potential or monomer density increase, respectively, the thickness of these surface-induced nematic layers grows, causing the disappearance of the disordered region in the center of the film.
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