Etymology and organization of surfactants

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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)

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Common surfactant molecules

Witten, Fig. 7.1

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.

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Large volume aqueous surfactants

Surfactant Structure
Fatty alcohols and alkylphenol ethoxylates
Alkylbenzene sulphonates
Fatty alcohol and fatty alcohol ether sulphates

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Oil soluble surfactants

Surfactant Structure
Sorbitan mono-oleate (Span 80)
Span 80
Solsperse 17000
Solsperse 17000
Polyisobutylene succinimide(OLOA 11000)
OLOA 11000

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Graded series of solutes - HLB scale

The 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.


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