Synthesis and properties of quaternary ammonium surfactants containing a methoxy benzyl substitute

Abstract

A series of novel methoxybenzyl-containing quaternary ammonium surfactants, namely N,N-dimethyl-N-alkyl-N-(m-methoxybenzyl) ammonium chloride (m-MDRA-n), were synthesized from m-methoxybenzyl chloride and N,N-dimethyl-N-alkyl tertiary amine. The structure of those products was characterized by FT IR, ¹H NMR, ¹³C NMR and MS. Their surface activity, absorption and aggregation behavior in aqueous solution at different temperature were studied by surface tension and conductivity method. The results showed that the critical micelle concentration (CMC) of m-MDRA-n was much lower than traditional surfactants of N,N-dimethyl-N-alky-N-benzyl ammonium chloride (BAC), which indicated that m-MDRA-n containing methoxybenzyl exhibited a higher surface activity and was easier to aggregate in aqueous solution. The standard free energy (ΔG_mic) and standard enthalpy (ΔH_mic) and standard entropy (ΔS_mic) were studied by isothermal titration calorimetry (ITC). In addition, m-MDRA-n exhibited a high bactericidal activity.