Chemistry Reference
In-Depth Information
Lyophobic (''solvent hating'').
The opposite of lyophilic. A hydrocarbon, for
example, would be lyophobic in relation to water. If the solvent in question
were changed to octane, the hydrocarbon would then become lyophilic.
Micelles.
Aggregated units composed of a number of molecules of a surface-active
material, formed as a result of the thermodynamics of the interactions between
the solvent (usually water) and lyophobic (or hydrophobic) portions of the mole-
cule.
Nonionic surfactants.
Surfactants that carry no electrical charge, as their water
solubility is derived from the presence of polar functionalities capable of signif-
icant hydrogen bonding interaction with water (e.g., polyoxyethylenes, sugars,
polyglycidols).
Oleochemicals.
Products derived from vegetable oils and similar raw materials.
Soap.
The name applied to the alkali salts of natural fatty acids, historically the
product of the saponification of natural fats and oils.
Solubilization.
The process of making a normally insoluble material soluble in a
given medium. In the following chapters, the term is applied in two ways: the
''solubilization'' of a hydrocarbon chain in water by chemical modification—
the addition of a head group—and the micellar solubilization of an oil phase
in water or vice versa.
Spreading coefficient.
A quantitative predictor of the ability or propensity of a
given liquid to spread over the surface of a second liquid or solid on the basis
of the surface tensions or surface energies of the two bulk phases and their
respective interfacial tension.
Surface-active agent.
The descriptive generic term for materials that preferen-
tially adsorb at interfaces as a result of the presence of both lyophilic and lyo-
phobic structural units, the adsorption generally resulting in the alteration of the
surface or interfacial properties of the system.
Surface tension.
The property of a liquid evidenced by the apparent presence of a
thin elastic membrane along the interface between the liquid and a vapor phase,
resulting in a contraction of the interface and reduction of the total interfacial
area. Thermodynamically, the surface excess free energy per unit area of inter-
face resulting from an imbalance in the cohesive forces acting on liquid mole-
cules at the surface.
Surfactant.
The widely used contraction for ''surface-active agent.''
Surfactant tail.
In surfactant science, generally used in reference to the hydropho-
bic portion of the surfactant molecule.
