Synthesis Of The Gemini Imidazolium Surfactant And Its Interactions With HPAM

Gemini imidazolium surfactant has the excellent qualities of both single long-chain imidazolium ionic liquids and ordinary surfactants,which shows unique properties in terms of the critical micelle concentration,surface properties and water solubility.Studying on the interfacial adsorption properties and the aggregation behavior in water as well as the interaction between surfactants and water-soluble polymer,is expected to provide important theoretical basis for different fields such as oil field exploitation,biological technology,material science etc.Three kinds of Gemini imidazolium surfactants with different chain lengths have been synthesized in this paper:[C₁₂-P-C₁₂im]Br₂?a?,[C₁₄-P-C₁₄im]Br₂?b?,[C₁₆-P-C₁₆im]Br₂?c?.The surfactants have been characterized by IR analysis,elemental analysis.The properties of the surfactants in aqueous solution have been studied by the measurement of surface tension,electrical conductivity,fluorescence spectroscopy and expansive rheology.The study results showed that the critical micelle concentrations of[C₁₂-P-C₁₂im]Br₂,[C₁₄-P-C₁₄im]Br₂,[C₁₆-P-C₁₆im]Br₂ were 0.067mmol·L^-1,0.023mmol·L^-1,0.197 mmol·L^-1 respectively and the surfactants showed superior surface activity.With the hydrophobic chain length increasing,?_max and?_CMC decreased gradually,A_min increased gradually,which meaned the efficiency of reducing the surface tension increased gradually.The micelle formation was a spontaneous process.The micellization process of[C₁₂-P-C₁₂im]Br₂ was entropy driven,and the micellization process of[C₁₄-P-C₁₄im]Br₂ was enthalpy driven,while the micellization process of[C₁₆-P-C₁₆im]Br₂ was entropy driven at low temperature,and enthalpy driven at high temperature.Along with the increase of the surfactant concentration and the formation of pre-micelles and micelles in solution,the polarity of the microenvironment of pyrene probe decreased gradually,and pyrene molecules gradually shifted from aqueous phase into the micelle cores of surfactants.The expansive modulus of the interfacial film increased with the expansive frequency increasing,and diffusion exchange process dominated interfacial behavior.The expansive elasticity dominated the expansive rheology,and the expansive elasticity increased with the hydrophobic chain length increasing.The interactions between[C_n-P-C_nim]Br₂ and HPAM in aqueous solution were also studied by measuring the surface tension,fluorescence spectrum and the expansive rheology of[C_n-P-C_nim]Br₂/HPAM mixed solution.The occurrence of interactions between the two in solution and the formation of their mixed micelles were found.[C₁₂-P-C₁₂im]Br₂ molecules were adsorbed onto the HPAM chain and formed pre micelles at low surfactant concentration.With the surfactant concentration increasing,[C₁₂-P-C₁₂im]Br₂ molecules and HPAM molecules began to form mixed micelles.Then surfactant micelles appeared in higher surfactant concentration solution.With HPAM concentration increasing,the interaction between surfactants and polymer appeared as more intense.The expansive modulus of mixed system increased with expansive frequency increasing.The expansive elasticity dominated the expansive rheology.With the hydrophobic chain length increasing,the interaction of[C_n-P-C_nim]Br₂ and HPAM decreased,and the elasticity of the mixed interfacial film increased.