Interfacial monolayers

The effects of interfacial monolayers on the extraction from drops are particularly striking. Early work showed that traces of either impurity or surface-active additives can drastically reduce extraction rates even plasticiser, in subanalytical quantities dissolved from plastic tubing by benzene, reduces the mass-transfer rate by about ten times by retarding... 

Boussinesq (B4) proposed that the lack of internal circulation in bubbles and drops is due to an interfacial monolayer which acts as a viscous membrane. A constitutive equation involving two parameters, surface shear viscosity and surface dilational viscosity, in addition to surface tension, was proposed for the interface. This model, commonly called the Newtonian surface fluid model (W2), has been extended by Scriven (S3). Boussinesq obtained an exact solution to the creeping flow equations, analogous to the Hadamard-Rybczinski result but with surface viscosity included. The resulting terminal velocity is... 

Interfacial monolayer, multilayer and polymer species which exhibit interesting examples of light and electrically stimulated functions such as isomerization and proton transfer in ISAs are also presented in this chapter. Such materials may represent the precursors for electrooptic switches and addressable molecular-based machines. 

Although the model was developed for a A-B alloy over the whole composition range (Li et al. 1989), application to the case of a solution that is infinitely dilute in B leads to simple expressions for the slope of enrichment factor at the interface YB/XB where YB is the molar fraction of B in the interfacial monolayer ... 

K. Motomura, Thermodynamics of Interfacial Monolayers, Adv. Colloid Interface Set 12 (1980) 1-42. (General thermodynamics of Langmuir and Gibbs monolayers the author s convention differs from the one adopted in this chapter.)... 

At an interface between a hydrocarbon and an immiscible liquid, the interface is composed of two monolayers, as indicated in Figure 1. At the interface, the adjacent layers of dissimilar molecules are in a different force field than the bulk liquid, and consequently, the molecules or atoms in these layers have a different pressure, intermolecular spacing, and chemical potential [5]. If the molecules in one of these monolayers are less strongly attracted by the adjacent phase than by its bulk liquid, the molecules in the interfacial layer have an increased intermolecular distance and are in tension. However, if the attraction by the adjacent phase is greater than that of the bulk liquid, the molecules of the interfacial monolayer have a shorter intermolecular distance and are under a two-dimensional pressure. The measured tension of the interface is always the sum of the tensions in the two interfacial... 

R. H. Tredgold, and R. Jones, Schottky-barrier diodes incorporating Langmuir-film interfacial monolayers, lEE Proc. 128 202 (1981). J.-P. Dodelet, H.-P. Pommier, and M. Ringuet, Characteristics and behavior of electrodeposited surfactant phthalocyanine photovoltaic cells, J. Appl. Phys. 53 4270 (1982). 

Interfacial monolayers may be subjected to cyclic deformadon (conpression and expansion). It is thus commonly found that the interlacial behaviw comprises a viscous and an elastic contribution. The elastic component K° can be expressed as... 

Vibrational sum frequency spectroscopy in conjunction with interfacial pressure measurements provide the first direct information about the structure of phospholipid monolayers composed of DLPC, DMPC, DPPC, and DSPC, adsorbed to the interface between two immiscible liquids. Temperature controlled experiments carried out with aqueous solutions of DSPC show the lipid bilayer gel to liquid crystalline phase transition temperature to play a pivotal role in determining interfacial monolayer concentration and alkyl chain structure. Even at equivalent interfacial concentrations longer chain phosphocho-line species form more disordered monolayers with a greater number of gauche defects than shorter chain phosphocholine species, as determined from relative intensities of vibrational bands in the CH stretching region. 

Scheme 1 Idealized representation of an interfacial monolayer assembly containing cylindrical binding sites...

To describe the phase behavior, contributions to the free energy arising from the bending of the interfacial monolayer, Ft from undulations of the lamellae, and from the entropy of mixing of water and oil domains, are discussed in... 

Amphiphiles are intriguing materials that self-assemble in various forms when mixed with oil and water. In disordered phases they take a structure of spherical droplets of water-in-oil (or oil-in-water) or a bicontinuous structure, in which both water and oil are separated from each other by intertwined interfacial films. In ordered phases they take a rather regular structure of hexagonal arrays of cylindrical tubules made of oil (or water) in surrounding water (or oil) or parallel arrays of alternative oil and water sheets. In these mixtures amphiphile molecules are mostly located at the interface of oil and water with their polar heads directed into water media and with apolar acyl tails into oil media, thus forming interfacial monolayers. The phase diagram of these structures depends strongly on temperature, pressure, kinds and concentrations of the... 

The reversible Type 3 isotherms are convex to the relative pressure axis and exhibits an indistinct point B. Type 3 isotherms arise when the affinity between adsorbate and adsorbent is weaker than the affinity between the adsorbate molecules (c < 2). This results in increased adsorption after the interfacial monolayer has formed. 

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