Wetting thermodynamic characteristics

Detailed investigations of the influence of the hydrophobic environment on the NMR spectra of adsorbed water and its thermodynamic characteristics for wetted powders of nanosilica... 

Direct Application of Thermodynamic Characteristics Related to Proper Wetting,... 

While a thermodynamic description of interfacial phenomena provides means for their macroscopic description, the use of molecular dynamic simulation enables one to study these phenomena on a molecular level. One of the first and most interesting developments in this direction was the analysis of the behavior of a drop of liquid on wetting and nonwetting solid surfaces. As a result, it was possible to reveal molecular insights into the mechanisms of wetting and nonwetting on a qualitative level and to relate these findings to the thermodynamic characteristics of these systems. 

The process of wetting involves the creation of new types of interfaces at the expense of others. For example, when a liquid droplet spreads over a solid, more of the SL and LG interface is created, whereas (psud of the) SG interface has vanished. All these changes are accompanied by chemges in thermodynaunlc characteristics, such as the Gibbs or Helmholtz energies of the system. Here, thermodynamics is useful to... 

The importance of the surface polarity and the surface characteristics for polymer adhesion has been considerably discussed in scientific literature [87]. A useful generalized theory of adhesion, however, can be built upon the basis of electrical attractions. The electrical attractions, resulting from uneven surfaces, which are not normally considered to be electrical, participate easily in attractive interactions if adhesives can be found that will wet them. Thus the reason that polyethylene and poly(tetrafluoroethylene) are difficult to bond is simply that available adhesives are thermodynamically more stable if their molecules attract one another than if they interact with low energy surfaces. The solution to this problem would... 

Standpoint, in practice, the type of topography present may carry with it certain practical consequences. For example, if the surface, rather than being randomly rough, has pores, crevices, capillaries, or other structures that have their own characteristic wetting and penetration properties, the apparent contact angle will be affected by the thermodynamics and kinetics associated with such structures. 

Each of these categories has been the subject of extensive experimental and theoretical investigations over the last decades. It would be an unrealistic task to cover in one article all applications of meso-thermodynamics. In particular, we do not consider such important topics as the thermodynamics of adsorption, wetting transitions, microphase separation in polymers, gels, or phase equilibria in confined fluids. Nor do we discuss the increasingly informative simulations of meso-scale systems (see, for example, refs 8, 22 and 23). Instead, in this Chapter we demonstrate only a few characteristic applications of meso-thermodynamics to each category, while emphasizing universality rather than specific details of the phenomena. 

For U-P[AB], features a-c provide a combination of thermodynamic driving forces that enhance soft block surface concentration. Of considerable interest is f, a feature that has been observed in the majority of new U-P[AB]. That is, some new and unexpected surface characteristics such as morphology or wetting behavior have... 

According to Everett s adsorption layer model [8,10,11,40], the heat of immersional wetting (Awi/t), a thermodynamic parameter characteristic of the solid-liquid interaction, can be easily calculated when the molar enthalpies, hi and /I2, of the components of the system are known. 

When attraction potentials are calculated using the Hamaker constants and Am and the layer thickness f prevailing in the given liquid mixtures, the value of the attraction potential is reduced by the wetting effect of benzene in the ben-zene-n-heptane mixture series at a constant interparticle distance of 0.1 nm, in complete agreement with our thermodynamic considerations. In the range of Xi = 0.4-0.6 for the methanol-benzene liquid pair, the minimal interparticle attraction can also be calculated from the attraction potential function and is found to coincide exactly with the appearance of the Newtonian flow characteristics of the suspension and the minima of the thermodynamic potential functions [36,39,64],... 

Immersion calorimetry is a useful technique for the characterization of porous materials. The heat evolved in the immersion process is directly related to the integral enthalpy of adsorption if the experiment is carried out at constant pressure and temperature [1]. The experimental data, which are obtained by immersion measurements, are normally used to determine the textural characteristics of the adsorbent, i.e. the micropore volinne or the surface areas accessible to the wetting liquid. In relation to the former Stoeekli et al [2] consider that a thermodynamic consequence of the Dubinin theory is the equation 1. 

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