The Synthesis And Properties Of Quaternary Ammonium Salt-Type Trimeric Surfactants

Oligomeric surfactants are a new type of surfactants that connect multiple hydrophilic groups and hydrophobic alkyl chains through chemical bonds at the hydrophilic head group or near it.Compared with traditional surfactants,due to their special molecular structure,they have unique physical and chemical properties.Therefore,it has good application prospects.In this project,a series of biodegradable quaternary ammonium salt type trimeric surfactants 3C_nest Q（n=12,14,16）were synthesized by esterification of glycerol with chloroacetic acid to obtain an intermediate,followed by quaternization with tertiary amines of different chain lengths.The structure of 3C_nest Q was characterized using modern characterization methods such as FT-IR,¹H NMR,and melting range analysis.The results showed that the actual structure was consistent with the theoretical structure.The surface tension of 3C_nest Q（n=12,14,16）solution at 25℃was measured using the suspension method,which has higher surface activity compared to traditional surfactants（DTAB）.Use a conductivity meter to measure the conductivity of 3C_nest Q（n=12,14,16）at 25℃,35℃,and 55℃,and drawκ-c relation curve.The CMC value and thermodynamic parameters of micellization were calculated,?G_mic^o<0 indicates that 3C_nest Q can spontaneously form micelles in solution.And?H_mic^o<0 indicates that the process is an exothermic reaction.The value of|-T?S_mic^o|is greater than?H_mic^o,indicating that the formation of micelles is mainly driven by entropy.The CMC values obtained by the conductivity method and the steady-state fluorescence probe method are basically consistent with those obtained by the suspension method.The emulsifying properties and foam properties of 3C_nest Q with carbon chain length of12,14 and 16 were measured by water separation time method and oscillation method.With the increase of 3C_nest Q concentration,the emulsifying properties and foam properties of3C_nest Q increased.3C_nest Q can transform the oil treated mica sheet from a hydrophobic surface to a hydrophilic one,resulting in a wetting reversal phenomenon.The corrosion inhibition performance of 3C₁₆est Q on N80 steel sheet in 1 mol/L HCl solution was measured by weight loss method and electrochemical method,when the concentration of 3C₁₆est Q reaches 7×10^-4mol/L,the corrosion inhibition efficiency for N80 reached 86.6%and 87.53%,respectively.The adsorption of 3C₁₆est Q on the surface of N80 steel sheet belongs to single molecular layer adsorption,which conforms to Langmuir adsorption model,and the polarization curve indicates that the corrosion of N80 steel in HCl medium belongs to cathode control,the AC impedance spectroscopy of 3C₁₆est Q indicates that the corrosion is controlled by the charge transfer step and belongs to a mixed type of corrosion inhibitor.