Interfacial surface energy

Free surface energy, interfacial enthalpy and Gibbs surface energy... 

The above kinetic equations, developed based on the thermodynamic approach of Gibbs (1928), Volmer and Weber (1926), and Becker and Doring (1935), belong to the so-called classical nucleation theories. They have been criticized for the use of surface energy (interfacial tension), cr, which is probably of little physical significance when applied to small molecular assemblies of the size of critical nucleus. 

By including a surface energy (interfacial energy) term in the equilibrium expression it is possible to make some interesting predictions. 

To overcome this anomaly, Knapp (1922) considered that the total surface energy (interfacial tension) of very small solid particles should be regarded as the sum of their normal surface energy plus the surface electrical charge that such particles would carry. From these considerations he derived for the case of isolated charged spheres an equation of the form... 

FIGURE 8.7 Schematic diagram summarising an overall approach used to calculate specific surface energies (interfacial tensions) of crystal surfaces in the presence of solution. Source Adapted from Hammond et al. [58]. Reproduced with permission of American Chemical Society. 

Background materials science Secondary bonds, surface energy, interfacial tension... 

The significance of the approach is that it covers the whole range of sizes from a dimer bond to the bulk solid and covers the states of surface, amorphous, and nanosolid of various shapes to bulk solid with defects inside, with almost no assumptions or freely adjustable parameters. Almost all of the imaginable and detectable quantities are consistently related to the BOLS correlation and the population of the undercoordinated atoms as well. For instance, the surface energy, interfacial energy, surface stress, the local mass density of liquid and solid are all functions of atomic separation and bond energy that are subject to the effect of... 

Resolution at tire atomic level of surfactant packing in micelles is difficult to obtain experimentally. This difficulty is based on tire fundamentally amoriDhous packing tliat is obtained as a result of tire surfactants being driven into a spheroidal assembly in order to minimize surface or interfacial free energy. It is also based upon tire dynamical nature of micelles and tire fact tliat tliey have relatively short lifetimes, often of tire order of microseconds to milliseconds, and tliat individual surfactant monomers are coming and going at relatively rapid rates. 

AU. dispersions are thermodynamically unstable, since the interfacial area and hence the surface energy tend to decrease, ie, agglomeration occurs. 

As it stands, eqn. (7.7) contains too many unknowns. But there is one additional piece of information that we can use. The interfacial energies, Ysl> Yes 7cl ct as surface tensions in just the way that a soap film has both a surface energy and a surface tension. This means that the mechanical equilibrium around the edge of the nucleus can be described by the triangle of forces... 

---