Synthesis and Properties of Three N-Alkyl Bis-Quaternary Ammonium Salt Surfactants

Three N-alkyl bis-quaternary ammonium salt surfactants were synthesized by using epichlorohydrin, trimethylamine hydrochloride, and N,N-dimethylalkyl amine as raw materials in a two-step manner. The products were characterized by ¹H NMR and MS, confirming the successful synthesis of 2-Hydroxy-N¹,N¹,N³,N³-tetramethyl-N³-dodecylpropane-1,3-diammonium chloride (HPDDC), 2-Hydroxy-N¹,N¹,N³,N³-tetramethyl-N³-tetradecylpropane-1,3-diammonium chloride (HPTDC), and 2-Hydroxy-N¹, N¹, N³, N³-tetramethyl-N³-hexadecylpropane-1,3-diammonium chloride (HPHDC). Moreover, the influence of carbon chain length on surface-active properties, foaming properties, and paraffin liquid emulsion stability was investigated. Results indicated that critical micelle concentrations (cmc) decreased with increasing carbon chain length from 12 to 16, and the cmc and γ_cmc were lower than those of Dodecyl trimethyl ammonium chloride (DTAC). The products exhibited better foam properties and worse emulsifying performance than those of DTAC. The Krafft points of all products were determined to be below 0 °C. Moreover, the products also demonstrated outstanding antibacterial properties.