title: Monte Carlo simulation of surfactant adsorption on hydrophilic surfaces.
abstract: Monte Carlo simulations have been carried out to study the adsorption behavior of small flexible amphiphilic molecules on solid surfaces from aqueous solutions. A simple coarse-grained solvent-free off-lattice model, with a square-well pair potential and hard core excluded volume effect, has been used. Adsorption isotherms for weakly and strongly hydrophilic homogeneous surfaces have been determined. The adsorbed layer displays a coexistence region with an upper critical point. Below the critical temperature a densely packed patch coexists with a two-dimensional gas-analogous phase. Above the critical temperature, a percolating network forms at higher surfactant concentrations. Depending on the ratio between the strength of the hydrophobic effect and the adsorption energy, a large variety of associates has been observed. Monolayers, bilayers, admicelles, small clusters, and percolating networks as typical associate structures have been found. In the four-region model, which is extended by the coexistence region, a characteristic adsorbed layer structure for each region can be detected. Intermediate structure types have been produced by variation of the adsorption energy.
authors.affiliation: Institute of Physical Chemistry, TU-Freiberg, Freiberg, Germany. Thomas.Zehl@chemie.tu-freiberg.de
authors.forename: T
authors.initials: T
authors.lastname: Zehl
authors.forename: M
authors.initials: M
authors.lastname: Wahab
authors.forename: P
authors.initials: P
authors.lastname: Schiller
authors.forename: H-J
authors.initials: HJ
authors.lastname: Mögel