Effect of the alkyl chain length on micelle formation for bis(N-alkyl-N,N-dimethylethylammonium)ether dibromides

Abstract

Dimeric alkylammonium salts – gemini surfactants – due to their unusual very low critical micelle concentration and minimal inhibitory concentration are subject to intensive research as surface active and antimicrobial compounds. Thanks to the presence of two positively charged nitrogen atoms and a large molecular surface, gemini surfactants are also very efficient corrosion inhibitors. To strengthen the electrostatic adsorption of ammonium cations on a metal surface, which is a key parameter in the inhibition of corrosion, heteroatoms (O, S, N, or P) and π-electron systems can be introduced into the gemini surfactant structure to increase chemical adsorption. In this study, we investigated the relationship between the alkyl chain length and critical micelle concentration for gemini surfactants containing an oxygen atom in the spacer, that is, bis( N -alkyl- N,N -dimethylethylammonium)ether dibromides, for potential use as corrosion inhibitors. • Cationic gemini surfactants with a modified spacer were synthesized. • Critical micelle concentrations were determined for all synthesized compounds. • Relationship between the length of the alkyl chain and cmc, Δ G o mic, and HOF was determined.