Phase transition electrostatic interactions

Stigter and Dill [98] studied phospholipid monolayers at the n-heptane-water interface and were able to treat the second and third virial coefficients (see Eq. XV-1) in terms of electrostatic, including dipole, interactions. At higher film pressures, Pethica and co-workers [99] observed quasi-first-order phase transitions, that is, a much flatter plateau region than shown in Fig. XV-6. 

While the v-a plots for ionized monolayers often show no distinguishing features, it is entirely possible for such to be present and, in fact, for actual phase transitions to be observed. This was the case for films of poly(4-vinylpyri-dinium) bromide at the air-aqueous electrolyte interface [118]. In addition, electrostatic interactions play a large role in the stabilization of solid-supported lipid monolayers [119] as well as in the interactions between bilayers [120]. 

It is of special interest for many applications to consider adsorption of fiuids in matrices in the framework of models which include electrostatic forces. These systems are relevant, for example, to colloidal chemistry. On the other hand, electrodes made of specially treated carbon particles and impregnated by electrolyte solutions are very promising devices for practical applications. Only a few attempts have been undertaken to solve models with electrostatic forces, those have been restricted, moreover, to ionic fiuids with Coulomb interactions. We would hke to mention in advance that it is clear, at present, how to obtain the structural properties of ionic fiuids adsorbed in disordered charged matrices. Other systems with higher-order multipole interactions have not been studied so far. Thermodynamics of these systems, and, in particular, peculiarities of phase transitions, is the issue which is practically unsolved, in spite of its great importance. This part of our chapter is based on recent works from our laboratory [37,38]. 

M Ilavsky. Effect of electrostatic interactions on phase transition in the swollen polymeric network. Polymer 22 1687-1697, 1981. 

Noncovalent interactions are primarily electrostatic in namre and thus can be interpreted and predicted via V (r). For this purpose, it is commonly evaluated on the surfaces of the molecules, since it is through these surface potentials, labeled VsCr), that the molecules see and feel each other. We have shown that a number of condensed-phase physical properties that are governed by noncovalent interactions—heats of phase transitions, solubilities, boiling points and critical constants, viscosities, surface tensions, diffusion constants etc.—can be expressed analytically in terms of certain statistical quantities that characterize the patterns of positive and negative regions of Vs(r) . 

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