Symmetric and Dissymmetric Pseudo-gemini Amphiphiles Based on Propoxylated Ethyl Piperazine and Fatty Acids

Summary: Novel symmetric and dissymmetric pseudo-gemini surfactants are synthesized using ethylpiperazine, propylene oxide and six different fatty acids (capric, lauric, myristic, palmitic, stearic, oleic) as starting materials. The synthesis follows a simple pathway excluding heating or catalyst. Important surface activity properties including critical micelle concentration (CMC), surface tension at CMC (γCMC), surface pressure at CMC (πCMC), negative logarithm of concentration to achieve 20 mN/ m reduction in surface tension (pC20), minimum area at interface (Amin) and maximum surface excess concentration (Γmax) are obtained through surface tension and electrolytic conductivity measurements. Antimicrobial properties of the synthesized amphiphiles are evaluated using disk diffusion method and are compared to those of standard antibiotic agents. Particle size distribution patterns are obtained using dynamic light scattering (DLS). This work investigates the effect of dissymmetry on various surface activity and antimicrobial properties. Dissymmetric pseudo-gemini amphiphiles have a few times higher CMC compared to analogous symmetric surfactants. However, better antimicrobial properties are observed when there is some dissymmetry between hydrophobic groups.