Etymology and organization of surfactants
Contents
Etymology
Technical terms (neologisms) are formed by combinations of prefixes and suffixes. English meanings are not literal translations, but interpretations of how the words are understood in this branch of science.
| English | Greek | Latin |
|---|---|---|
| oil | lipo- | oleo- |
| water | hydro- | aqua- |
| solvent | lyo- | solvo- |
| affinity | -philic | |
| lack-of-affinity | -phobic | |
| nature | -pathic | |
| science | -logy | |
| flow | rheo- |
hydrophilic = with affinity for water
lipophilic = with affinity for oil
lyophilic = with affinity for the solvent
lyophobic = lack of affinity for the solvent
amphipathic = combining both natures (oil and water understood)
amphiphilic = with affinity for both (oil and water understood)
Common surfactant molecules
Five common surfactant molecules.
Top left: SDS also called sodium lauryl sulfate (a leading ingredient in house-hold cleaning products lie soap, detergent, and shampoo, a anionic surfactant.
Top right: the cationic cetyl trimethyl ammonium bromide (CTAB).
Bottom left: the phospholipid 1-palmitoyl-2-oleoylphosphatidylcholine (POPC)
Center right: sodium bis(2-ethylhexyl)sulfosuccinate (AOT) AOT is a rare surfactant - it is soluble and active in both oil and water.
Botton right: pentaethylene glycol monodecyl ether (C12EO5), a non-ionic surfactant.
Large volume aqueous surfactants
| Surfactant | Structure |
|---|---|
| Fatty alcohols and alkylphenol ethoxylates | |
| Alkanolamides | |
| Alkylbenzene sulphonates | |
| Fatty alcohol and fatty alcohol ether sulphates |
Oil soluble surfactants
| Surfactant | Structure |
|---|---|
| Sorbitan mono-oleate (Span 80) | |
| Solsperse 17000 | |
| Polyisobutylene succinimide(OLOA 11000) |
Graded series of solutes - HLB scale
HLB stands for hydrophile / lipophile / balance. The scale measure the affinity of non-ionic surfactants for oil as opposed to water. The method introduced by Griffin in 1954 assigns an index
HLB = 20 * Mh / M,
where Mh / M is the proportion of the molecular mass that is hydrophillic. A higher HLB indicates a higher water solubility.
(Sources: http://lotioncrafter.com/pdf/The_HLB_System.pdf, http://en.wikipedia.org/wiki/Hydrophilic-lipophilic_balance)
