Synthesis And Properties Of A Zwitterionic Tetrameric Surfactant

Tetrameric surfactants are formed by linking four traditional hydrophilic head groups and four hydrophobic alkyl chains at or near the hydrophilic head group with a linking group.Compared with the traditional surfactants and Gemini surfactants,tetrameric surfactants have lower krafft points,higher surface activity,lower critical micelle concentration.The values of their relative molecular mass are between the values of the traditional surfactant and high molecular surfactant.Thus,there is a good application prospect in the high-performance materials,the chemical flooding technology,and the molecular self-assembly,and so on.1.In this paper,three series of zwitterionic tetrameric surfactant with different hydrophobic chain lengths[4C_ntetra Z?n=12,14,16?]were synthesized through etherification,quaternization,and sulfonation reaction,in which the pentaerythritol was used as the core and the raw materials were epichlorohydrin,long-chain tertiary amine,and chlorosulfonic acid,respectively.The structures of 4C_ntetra Z were confirmed with infrared spectroscopy and nuclear magnetic resonance spectroscopy,and there purity were determined by melting point test.2.the surface activities,the polarity in water and aggregation morphology of4C_ntetra Z were studied by surface tension method,steady-state fluorescence spectroscopy and dynamic light scattering method.The surface tension test results show that 4C_ntetra Z have good surface activities,and their critical micelle concentration?cmc?are 1?2 order lower than those of traditional single chain surfactant and Gemini surfactant.The 4C_ntetra Z molecules tend to be adsorbed on the air/water interface and can be tightly arranged at the gas-liquid interface,which can effectively reduce the surface tension of water.The thermodynamic functions of the micelle formation process were calculated,and the results show that the micellization of 4C_ntetra Z molecules can proceed spontaneously in the temperature range of 25?55°C.The influence of entropy drive gradually decreases while the effect of enthalpy driving gradually increases,which can show that there exists obvious enthalpy-entropy compensation phenomenon in the micelle formation process.The4C_ntetra Z molecules easily form vesicle structure with large sizes at the high concentration while is inclined to occur in spherical micelle with small sizes at the low concentration.The inner region of the formed aggregates occur in the low polarity,and have close packed structure.3.The antibacterial,foam and emulsifying properties of 4Cntetra Z were tested,respectively.4C_ntetra Z have good antibacterial properties against bacteria,and the bacteriostatic rates against S.aureus were all close to 100%.the bacteriostatic rates of4C₁₂tetra Z,4C₁₄tetra Z,4C₁₆tetra Z against E.coli are 98.1%,85.6%,43.2%,respectively,which shows that the bacteriostatic performance reduce with increase of alkyl chain.4C_ntetra Z have good foam performances,and the foam stabilization rate of 4C₁₂tetra Z,4C₁₄tetra Z,4C₁₆tetra Z at the concentration of 0.5 wt.%are 95.84%,96.04%,96.96%,respectively.The polarizing microscope test show that 4C_ntetra Z have good emulsifying performances and form O/W emulsion,the particle size is relatively small and the particle size distribution is uniform.The particle size was measured with laser particle size analyzer,and the results show the particle size of the emulsion is less than 1?m.The interfacial tension between 4C_ntetra Z solution and crude oil obtained Daqing oilfield were tested by Spinning drop method,and the order of interface tension between 4C_ntetra Z solution and crude is 10^-1.