B General Structural Features and Behavior of Surfactants

The molecules at a surface have higher potential energies than those in the interior. This is because they interact more strongly with the molecules in the interior of the substance than they do with the widely spaced gas molecules above it. Work is therefore required to bring a molecule from the interior to the surface. [Pg.2]

Anionic. The surface-active portion of the molecule bears a negative charge, for example, RCOO Na (soap), RC6H4SO3 Na+ (alkylbenzene sulfonate). [Pg.3]

Cationic. The surface-active portion bears a positive charge, for example, RNH Cl- (salt of a long-chain amine), RN(CH3) CI (quaternary ammonium chloride). [Pg.3]

Zwitterionic. Both positive and negative charges may be present in the surface-active portion, for example, RN H2CH2COO (long-chain amino acid), RN+(CH3)2CH2CH2S03 (sulfobetaine). [Pg.3]

Nonionic. The surface-active portion bears no apparent ionic charge, for example, RCOOCH2CHOHCH2OH (monoglyceride of long-chain fatty acid), RCgH OC H OH (polyoxyethylenated alkylphenol), R C H OH(polyoxyethylenated alcohol). [Pg.3]

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