The Synthesis Of Gemini Quaternary Ammonium Salt-type Surfactants With Amide Groups And Their Properties

In this paper,the Gemini quaternary ammonium salt-type surfactant（2C_nGe QS,n=12,18）with hydroxyl and amide groups in the molecular structure was prepared by two-step amidation reaction and quaternization reaction;The molecular structure of 2C_nGe QS was characterized by FT-IR,¹H NMR and elemental analysis.The results showed that the prepared product was consistent with the target surfactant 2C_nGe QS.The critical micelle concentration of aqueous solution of amido Gemini quaternary ammonium surfactant 2C_nGe QS was determined by Wilhelmy method,conductivity method and steady-state fluorescence probe method;The effectiveness(π_CMC),adsorption efficiency(p C₂₀)and maximum surface adsorption capacity(Γ_Max)were calculated,minimum molecular cross-sectional area(A_min)and other thermodynamic parameters.The results showed that the critical micelle concentration（CMC）of 2C_nGe QS decreased with the increase of hydrophobic chain length,and 2C_nGe QS had higher surface activity than single chain surfactant;The thermodynamic parameters show that the micellization process and adsorption process of2C_nGe QS are spontaneous;The aggregate morphology of 2C_nGe QS was determined by dynamic light scattering and transmission electron microscope（TEM）.The results show that the aggregate form of 2C_nGe QS in aqueous solution is spherical micelle.The Krafft point of 2C_nGe QS is lower than 0℃;The foam,emulsifying and wetting properties of 2C_nGe QS solution were determined.The results showed that its foam,emulsifying and wetting properties were good.The corrosion inhibition performance of surfactant 2C_nGe QS on A3 carbon steel specimen in 1mol/L HCl solution was investigated by weight loss method and electrochemical impedance spectroscopy.The results of weight loss method showed that when its concentration was 5×10^-3mol/L,the corrosion inhibition rate has reached 97.15%and 97.94%;The corrosion inhibition performance of 2C_nGe QS is better than that of DTAB;The surface morphology of A3 carbon steel specimen was observed by scanning electron microscope（SEM）.The results show that 2C_nGe QS has good corrosion inhibition performance.