Wetting Properties Surface Energy and Tension

Even when much effort was invested by the scientific community to understand wetting, surface energy and other apparently simple concepts, lots of questions stiU remain open in which we will discuss in this chapter. The exposition will be focused on some of those controversies with the hope to contribute to both the reader s knowledge acquisition and inquisition. 

Both wetting and adhesion are manifestations of the attractive forces that exist between molecules. A molecule in the bulk of a phase suffers a zero net force exerted by their neighbors, but when a molecule is on the surface, the surrounding molecules exert an unbalanced net force which puUs the surface molecule towards the interior of the phase (Fig. 4). This net force is manifested as a surface tension. As some of the bonds present in the molecule when it is in the bulk of the phase are cut when it is 

Molecular interactions can be classified into non-polar (np), polar (p), and a third kind of forces called associative forces, which include Lewis acid basic interactions like hydrogen bonding ah). 

Non-polar forces arise from instantaneous dipoles produced by the motion of electrons within the molecule. Those interactions are called London dispersion forces. 

Its variation with the distance between the centers of the molecules is well described by the negative of the gradient of the Lennard-Jones potential  

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