Critical specific surface free energy

According to Rehbinder and Shchukin the above condition has a simple physical meaning if the particles are of colloidal dimensions, and the interfacial tension is low, the spontaneous separation of particles from a macroscopic phase becomes possible, since the work required to form a new surface is compensated by the gain in energy upon the involvement of the newly formed particles in thermal motion. There is a critical value of the specific surface free energy, ocr, below which the spontaneous dispersion process becomes possible. This critical value is given by... 

Many interesting correlations have been established between the critical surface tension of materials (or other approximations of surface free energy) and protein adsorption, cell adhesion, and thrombus formation (41-48). Unfortunately, very few studies in which a biological response has been related to a specific surface chemistry exist. One study in which such a relationship was established, demonstrated the power of the contact angle method in analyzing surface structure related to blood compatibility (40). The blood compatibility of Stellite alloy heart valves was not due to the alloy itself, but to the closely packed methyl group structure associated with a tallow polishing compound used to finish the valve. Very recently, the power... 

And the free energy of the critical cluster is still Equation 4-4. If the cluster is not spherical (e.g., the cluster could be a cube, or some specific crystalline shape), then the specific relations between i and cluster volume and surface area are necessary to derive the critical cluster size. 

As in the case of small molecules, the crystallization process involves nucle-ation and diffusion of the relevant entity to the surface site. The formation of the critical nucleus will be controlled by thermodynamics. The total change in free energy AG is the sum of contributions from the bulk and surface energies. Using the convention which we introduced in Figure 6.1, where cr,- is the specific surface energy of surface i and At is the area, then the free energy can be described by... 

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