Cationic surfactants protective properties

Some corrosion inhibitors have properties that are normally associated with surfactants. Recently, Pebere et al. studied 2-hexadecylimidazoline and 2-hexadecy-iimidazole as inhibitors of a carbon steel in HCI containing H2S, and they obtained a protection vs. inhibitor concentration profile similar to that often seen with cationic surfactants that is, there was a sharp increase in protection below the critical micelle concentration (CMC) followed by a leveling off at the CMC. Above the CMC, the inhibitors appear to form thick adherent films that act as diffusion barriers. In contrast, a study of the effects of ethoxylated alcohols (nonionic surfactants) and quaternary nitrogen salts (cationic surfactants) on the performance of the inhibitor cinnamaldehyde on mild steel in 15% HCI indicates that in these cases the surfactants co-adsorb with the inhibitor and produce a maximum effect far below their CMCs. ... 

Biologically Protective Finishes Cellulosics particularly used in outdoor conditions are susceptible to attack by microorganisms. Treatment of cellulosics with chlorinated phenolic derivatives, organometallics such as copper 8-hydro>gfquinolate, cationic surfactants, or grafting with polyacrylonitrile can reduce biological attack, although reductions in certain other properties may be expected. 

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