Study On The Synthesis And Properties Of Gemini Amphoteric Surfactant

A novel Gemini amphoteric surfactant, sodium N,N'- bis-(β- stearacyloxy)- ethylenediamine-diacetate ,was synthesized and characterized.Sodium N,N'- bis-(β- stearacyloxy)- ethylenediamine-diacetate was synthesized by using N,N'-bis-(β-hydroxyethyl)-ethylenediamine to react with sodium chloroacetate to form an intermediate product, sodium N,N'- bis-(β-hydroxyethyl)-ethylenediamine- diacetate, followed by reacting with stearoyl chloride. The optimum reaction conditions were obtained via soaponification method and orthogonal experiments. For the intermediate product, sodium chloroacetate and N,N'-bis-(β-hydroxyethyl)- ethylenediamine in molar ratio 3 reacted at 25℃for 24 h. For the final product, stearoyl chloride and intermediate product in molar ratio 2.5 reacted at 20℃for 5 h while maintaining the volume ratio of water and chloroform at 1:2 and the pH in the range of 9.0~10.0. The structure of intermediate product and final product were characterized by IR spectrum and MS spectra.The purity of Gemini surfactant was analyzed through HPLC to determine the mass percent content.Under different salts(NaCl,NaF,NaBr), the surface tension of sodium N,N'- bis-(β- stearacyloxy)- ethylenediamine-diacetate was determined by the ring method (Du Nouyβmethod). It was found that the critical micelle concentration(cmc) and the corresponding surface tension at such concentration (γcmc) were determined from theirγ-lgc curves, which were in the ranges 0.42×10-4~2.40×10-4 mol·L-1 and 29.84~35.28 mN·m-1.Through the calculational of micelle thermodynamic parameters, it was concluded that the forming of micelle was driven by entropy.The interactions of the Gemini/AEO9 and Gemini/DTAB mixed systems have been investigated separaterly at 298 K in the solution of 0.1 mol·L-1NaCl. The value ofβwas calculated according to regular solution theory. Moreover, we applied criterion to decide the condition of if there had synergism between surfactants.The surfactant also showed good properties of emulsification, wetting and foaming.