Interfacial contact orientation effects

Such smoothing of the threshold between polarities within the interfacial discontinuity surface is possible when the polarity of the introduced third component is intermediate with respect to those of two other components, that make up the phases in contact. The smoothing is especially effective, when it is achieved via the adsorption of diphilic molecules containing segments with different polarities. These molecules are the organic surfactants that can smoothen the difference in polarity between water and any solid or liquid hydrocarbon phase ( further referred to as oil ). When the adsorption takes place, the polar heads of the surfactant molecules are oriented towards water, while the hydrocarbon chains face the oil phase (Fig. III-5). As... 

In some cases, long-chain alcohols have been found to behave as polar oils, with a tendency to place themselves not in the oil phase bulk but near the interface [60]. This means that the oil phase which is in contact with the interfacial C layer is richer in alcohol than the overall oil phase, with a consequence on the interactions. This alcohol role has been called a lipophilic linker effect because the alcohol molecules that are located near the interface are not randomly oriented like oil molecules in the bulk, but with their OH group pointing toward the interface (i.e., perpendicular to the interface), a conformation that produces an additional ordering in the oil molecules that ends up in a better interaction [83,84]. 

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