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Linear chain surfactants at a planar interface: a comparative Monte Carlo study of several lattice models
Author(s) -
Haas Frank M.,
Lai PikYin,
Binder Kurt
Publication year - 1993
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/mats.1993.040020605
Subject(s) - monte carlo method , lattice (music) , square lattice , monomer , planar , chain (unit) , chemical physics , alkane , monolayer , polymer , materials science , lattice model (finance) , tilt (camera) , long chain , chemistry , statistical physics , molecular physics , crystallography , physics , nanotechnology , hydrocarbon , geometry , composite material , mathematics , organic chemistry , polymer science , statistics , computer graphics (images) , astronomy , computer science , acoustics , ising model
Linear chain surfactants in a densely packed arrangement (such as alkane chains in lipid monolayers in the “uniform tilt” structures) are described by a crude coarse‐grained model where the endgroups grafted on the interface form a regular lattice and the chains are described by the bond fluctuation model with chains containing N = 4 effective monomers only. Square‐well interactions between the monomers are studied for both the attractive and repulsive case for three choices of the interaction range. None of these models exhibits a structure with uniform tilt. For attractive interactions the last bond has a strong tendency to fold back thus leading to a very high density close to the interface. Only when an intrachain‐potential favoring stiff chain configurations also is included one can obtain configurations with uniform tilt order. Although related models (with much longer chain lengths and lower grafting densities) are very useful for the study of polymer brushes, the present case of very short chains in a high‐density state clearly is plagued by various lattice artefacts and it is concluded that for modelling linear chain surfactants one should use an off‐lattice model even on a coarse‐grained level.