Effect of Long-Range and Steric Hydrophilic Interactions on Micellization of Surfactant Solutions:  A Monte Carlo Study in 2-D

In this work, we present Monte Carlo computer simulation results of a primitive model of self-assembling system based on a flexible 3-mer chain interacting via square-well interactions. The effect of switching off the attractive interaction in an extreme sphere is analyzed, since the anisotropy in the molecular potential promotes self-organization. Before addressing studies on self-organization it is necessary to know the vapor liquid equilibrium of the system to avoid to confuse self-organization with phase separation. The range of the attractive potential of the model, λ, is kept constant and equal to 1.5σ, where σ is the diameter of a monomer sphere, while the attractive interaction in one of the monomers was gradually turned off until a pure hard body interaction was obtained. We present the vapor-liquid coexistence curves for the different models studied, their critical properties, and the comparison with the SAFT-VR theory prediction [A. Gil-Villegas, A. Galindo, P. J. Whitehead, S. J. Mills, G. Jackson, and A. N. Burgess, J. Chem. Phys. 106, 4168 (1997)]. Evidence of self-assembly for this system is discussed.

Section: B the K = 0 Systemmentioning

confidence: 99%

Monte Carlo simulation of flexible trimers: From square well chains to amphiphilic primitive models

Jiménez-Serratos

Gil‐Villegas

Vega

et al. 2013

“…We sample the equilibrium configurations of the system in the canonical ensemble using a Monte Carlo (MC) dynamics in which both amphiphile reptation and translation moves are attempted [43,45]. In the reptation move, an attempt is made to move one end of the chain onto a solvent-occupied site, with the rest of the amphiphile following in train, and the displaced solvent unit moving to the site vacated by the other end of the chain.…”

Section: B Simulation Protocolmentioning

confidence: 99%

Simulations of a lattice model of two-headed linear amphiphiles: Influence of amphiphile asymmetry

Jackson

Mohareb

MacNeil

et al. 2011

Using a 2D lattice model, we conduct Monte Carlo simulations of micellar aggregation of linearchain amphiphiles having two solvophilic head groups. In the context of this simple model, we quantify how the amphiphile architecture influences the critical micelle concentration (CMC), with a particular focus on the role of the asymmetry of the amphiphile structure. Accordingly, we study all possible arrangements of the head groups along amphiphile chains of fixed length N = 12 and 16 molecular units. This set of idealized amphiphile architectures approximates many cases of symmetric and asymmetric gemini surfactants, double-headed surfactants and boloform surfactants. Consistent with earlier results, we find that the number of spacer units s separating the heads has a significant influence on the CMC, with the CMC increasing with s for s < N/2. In comparison, the influence of the asymmetry of the chain architecture on the CMC is much weaker, as is also found experimentally.

“…In a previous work, 28 we modeled and simulated the aggregation behavior of coarse-grained models of surfactant molecules in aqueous solutions. The silane molecules have a chainlike structure similar to the surfactant molecules, and both have a hydrocarbon backbone.…”

Section: Simulation Model and Proceduresmentioning

confidence: 99%

“…32,33 Based on this we elect to use the truncation method with a cutoff distance of 30 grid units, which was used with success in our previous work on surfactants. 28 The total energy of the system is, therefore, given by the following expression:…”

Section: Simulation Model and Proceduresmentioning

confidence: 99%

“…Owing to the similarity between surfactant and silane structures the interaction energies ⑀ WT , ⑀ TH , and ⑀ WH have been taken from our previous work on surfactants. 28 The reactive head groups in silanes are believed to cause polymerization in the aqueous environment. Therefore, a very strong short-range nearest neighbor attractive interaction, ⑀ HH , is assumed between the head groups.…”

Section: Simulation Model and Proceduresmentioning

confidence: 99%

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Two-dimensional Monte Carlo simulations of ionic and nonionic silane self-assembly on hydrophilic surfaces

Kapila

Almanza-Workman

Deymier

et al. 2004

Aqueous chemistries have recently been shown to be useful for the deposition of hydrophobic films of nonionic and cationic silanes on hydrophilic substrates for the prevention of stiction in MEMS. The Monte Carlo method is used to simulate in two dimensions the self-assembly of silane films on a hydrophilic surface. We investigate the impact of charged group in cationic silane on the overall structure of the films. We characterize the film structure with spatial pair correlations at each molecular layer of the deposited films. The simulations reveal long-range correlations for the film of cationic silanes. Based on our two-dimensional simulations, we report an average "most probable" structure for the films of nonionic and cationic silanes.