Semifluorinated hydrocarbons:  primitive surfactant molecules

Turberg, Michael; Brady, James E.

doi:10.1021/ja00231a034

Cited by 160 publications

(142 citation statements)

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“…Consequently, they display the "dual character" of amphiphilic molecules and the physics of orientational ordering of smectogenic liquid crystals. Indeed, aggregation in solvents selective for one of the blocks 18,19 and smectic liquid crystalline phases have been reported for PFAAs. 20−22 It should be kept in mind, however, that unlike common hydrophilic/hydrophobic amphiphiles in which one of the driving forces for organization is the strong interaction between polar or ionic groups, in PFAA, the origin of organization rests on a subtle balance between weak and even weaker interactions.…”

Section: Introductionmentioning

confidence: 99%

Liquid Mixtures Involving Hydrogenated and Fluorinated Chains: (p, ρ, T, x) Surface of (Ethanol + 2,2,2-Trifluoroethanol), Experimental and Simulation

Duarte¹,

Silva²,

Rodrigues³

et al. 2013

J. Phys. Chem. B

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The effect of mixing hydrogenated and fluorinated molecules that simultaneously interact through strong hydrogen bonding was investigated: (ethanol + 2,2,2-trifluoroethanol) binary mixtures were studied both experimentally and by computer simulation. This mixture displays a very complex behavior when compared with mixtures of hydrogenated alcohols and mixtures of alkanes and perfluoroalkanes. The excess volumes are large and positive (unlike those of mixtures of hydrogenated alchools), while the excess enthalpies are large and negative (contrasting with those of mixtures of alkanes and perfluoroalkanes). In this work, the liquid density of the mixtures was measured as a function of composition, at several temperatures from 278.15 to 353.15 K and from atmospheric pressure up to 70 MPa. The corresponding excess molar volumes, compressibilities, and expansivities were calculated over the whole (p, ρ, T, x) surface. In order to obtain molecular level insight, the behavior of the mixture was also studied by molecular dynamics simulation, using the OPLS-AA force field. The combined analysis of the experimental and simulation results indicates that the peculiar phase behavior of this system stems from a balance between the weak dispersion forces between the hydrogenated and fluorinated groups and a preferential hydrogen bond between ethanol and 2,2,2-trifluoroethanol. Additionally, it was observed that a 25% reduction of the F−H dispersive interaction in the simulations brings agreement between the experimental and simulated excess enthalpy but produces no effect in the excess volumes. This reveals that the main reason causing the volume increase in these systems is not entirely related to the weak dispersive interactions, as it is usually assumed, and should thus be connected to the repulsive part of the intermolecular potential.

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Section: Introductionmentioning

confidence: 99%

Liquid Mixtures Involving Hydrogenated and Fluorinated Chains: (p, ρ, T, x) Surface of (Ethanol + 2,2,2-Trifluoroethanol), Experimental and Simulation

Duarte¹,

Silva²,

Rodrigues³

et al. 2013

J. Phys. Chem. B

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“…One could, therefore, argue that these models are not appropriate for studying these self-assembly phenomena in aqueous solutions. As already noted by Lipowsky et al [8], these enthalpic models could, indeed, correspond better to enthalpy-driven self-assembly in non-polar solvents [23][24][25][26]. One could alternatively argue that some degree of entropic rearrangement is actually incorporated into those models via the packing of the solvent around the hydrophobic tail induced by the strong solvent-solvent attraction.…”

Section: Introductionmentioning

confidence: 71%

Coarse-grained simulation of amphiphilic self-assembly

Michel

Cleaver

2007

The Journal of Chemical Physics

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We present a computer simulation study of amphiphilic self assembly performed using a computationally efficient single-site model based on Gay-Berne and Lennard-Jones particles. Molecular dynamics simulations of these systems show that free self-assembly of micellar, bilayer and inverse micelle arrangements can be readily achieved for a single model parameterisation. This self-assembly is predominantly driven by the anisotropy of the amphiphile-solvent interaction, amphiphile-amphiphile interactions being found to be of secondary importance. While amphiphile concentration is the main determinant of phase stability, molecular parameters such as headgroup size and interaction strength also have measurable affects on system properties.

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“…Fluorocarbon-hydrocarbon diblock compounds 2 form gels with saturated and aromatic hydrocarbon solvents, whereas inverted micelles were formed in fluorinated solvents. The gelating capability and surfactant like behavior is contributed to the mutual solvophicity of the hydrocarbon and fluorocarbon moiety [9,10]. The organogelator 3 is clear example of gelation of organic solvents by surfactant type of molecules [11,12].…”

Section: Fatty Acid and Surfactant Type Gelatorsmentioning

confidence: 99%