Surface and biological activity of N-(((dimethoxybenzylidene)amino)propyl)-N,N-dimethylalkyl-1-ammonium derivatives as cationic surfactants

The colloidal and biological properties of three newly cationic surfactants were investigated. The chemical structure of the prepared cationic surfactants which formed through condensation reaction between dimethylaminopropylamine (DMAPA) and 3,4-dimethoxybenzaldehyde then quaternized by three fatty alkyl bromide was confirmed by FTIR, 1H NMR and mass spectroscopy. Many important physiochemical parameters, such as the critical micelle concentration (CMC), maximum surface excess (Γmax), minimum surface area (Amin), efficiency (PC20) and effectiveness (πCMC) have been determined utilizing surface tension. By increasing the hydrophobic chain length, the values of CMC & Гmax decrease while Amin value was increased. The thermodynamic parameters (ΔG°mic and ΔG°ads) showed that adsorption and micellization processes are spontaneous. It is clear that the prepared cationic surfactants tend to adsorb at surface, then it aggregate to form micelle. The prepared surfactants showed good biological activity against Gram-positive and Gram-negative bacteria and fungi.