Synthesis and Surface Properties of Novel Quaternary Ammonium Gemini Surfactants with Polar Head Groups Containing 2‐Hydroxypropyl Moieties

Abstract

AbstractThe purpose of this paper is to comprehend in‐depth the effect of the surfactant structure on its and physicochemical properties such as surface/interfacial properties, foam stability, wettability, and biodegradability. To this end, quaternary ammonium Gemini surfactants, alkanediyl‐α,ω‐bis[(2‐hydroxypropyl)dodecylammonium] dibromide (abbreviated as Cm‐n‐Cm[iso‐Pr(OH)]2 with m = 12, 14 and n = 2, 3, 4) were synthesized via substitution and quaternization reactions, and their chemical structures were characterized by Fourier transform infrared (FT‐IR) and nuclear magnetic resonance (1HNMR) spectroscopies. The results showed that with the decrease of the spacer length, the surface tension was reduced more strongly, and with the increase of the alkyl tail length, micelles were more easily formed. Besides, the highest surface activity of C14‐2‐C14[iso‐Pr(OH)]2 was observed by increasing NaCl concentration to 200 g L−1. The temperature had a great influence on thermodynamic parameters of the adsorption and micellization. The interfacial tension between 0.26 g L−1 C14‐2‐C14[iso‐Pr(OH)]2 solution and oil could reach 0.022 mN m−1. An elongation of the spacer chain in C14‐n‐C14[iso‐Pr(OH)]2 was unfavorable to foam stability. Besides, the oil‐wetted core, which was aged in 0.6 g L−1 C14‐2‐C14[iso‐Pr(OH)]2 solution, exhibited more hydrophilicity. Cm‐n‐Cm[iso‐Pr(OH)]2 surfactants produced higher biodegradable rates in river water (≥ 90% after 28 days) than the biodegradable surfactant of international recommendation (71% after 28 days) at 30 °C.