The Synthesis And Properties Of Sulfur-containing Quaternary-ammonium-salt-type Gemini Surfactants

Oligomeric surfactant is a new type of surfactant containing two or more hydrophilic and lipophilic groups,compared with traditional single-chain surfactants,because of its high surface activity and the ability to form a variety of aggregates in aqueous solutions,thus attracting people’s attention.The paper used 3-3 thiodipropionic acid,chloroethanol and tertiary amines with different alkyl chain lengths as raw materials and synthesized a sulfur-containing,quaternary ammonium salt dimeric surfactants[2C_ncoes T（n=12,14,16）]through esterification and quaternization reaction,and their structures were characterized by modern characterization methods,such as ¹H NMR,FT-IR,and melting range analysis.The actual structure of the product is consistent with the theoretical structure.The physicochemical properties of 2C_ncoes T were studied by platinum plate method,conductometric method,steady-state fluorescent probe method,dynamic light scattering method.The experimental results show that the products have good surface activities,in which the CMC andγ_CMCof 2C₁₂coes T at 25℃are 0.48mmol/L,35.17m N/m,better than traditional surfactant（DTAB）with the same alkyl chain length.In addition,the CMC values of 2C_ncoes T determined by platinum plate method,steady-state fluorescent probe method and conductivity method were basically the same.The results of dynamic light scattering show that surfactants with shorter alkyl chains tend to form small micelles,and are inclined to bend to form large micelles with the increase of alkyl chain lengths.The thermodynamic parameters of 2C_ncoes T micellization indicate that the micellization process in aqueous solution is spontaneous and endothermic,and is mainly driven by entropy.Experiments of water separation time method and shaking method show that 2C_ncoes T have better emulsifying and foaming properties.The results of extinction dilution method indicates that2C₁₂coes T has good bactericidal performance,in which the sterilization rates for both SRB and TGB at 40 mg/L exceed 97%.The corrosion inhibition of 2C₁₂coes T on N80 carbon steel in 1mol/L hydrochloric acid solution was investigated by weight loss method and electrochemical method.When the concentration is 7×10^-4mol/L,the adsorption on the surface of N80 steel conforms to the Langmuir isotherm model,and belongs to the mixed physical and chemical adsorption.The polarization curves show that the corrosion of N80 steel in the hydrochloric acid corrosion medium belongs to the cathodic control,and the 2C₁₂coes T belongs to the mixed-type inhibitor.The AC impedance spectrums show that the corrosion process of N80 steel in the acidic medium is mainly controlled by the charge transfer step.