季铵盐双子表面活性剂N,N'-双(十二/十四烷基二甲基)-1,4-对苯二甲基氯化铵盐的合成及性能

Synthesis and Surface Activity of Cationic Gemini Surfactant N,N'-bis(Octadecyl/tetradecyl dimethyl)-1,2-dichloro-1,4-benzene Dimethyl Ammonium Salt

分别以十二烷基二甲基叔胺、十四烷基二甲基叔胺和对二氯苄(XDC)为原料,"一步法"合成了两种季铵盐双子表面活性剂,通过正交实验优化了合成条件,结果表明,当n(叔胺)∶n(XDC)=2.4∶1、反应温度75℃、反应时间2 h时,XDC转化率达到100%;产物结构经红外光谱(FTIR)、核磁共振氢谱(1HNMR)和碳谱(13CNMR)进行了确认。研究了其表面活性,结果表明:25℃时,碳链长度分别为12和14时,表面活性剂临界胶束浓度(CMC)分别为1.36×10-5和2.56×10^(-6)mol/L,表面张力(γCMC)分别为40.71和35.37 m N/m;p C20值分别为5.63和6.18;表面过剩吸附量(Γmax)分别为2.41×10^(-6)和3.09×10^(-6)mol/m^2;分子最小截面积(Amin)分别为0.69和0.54 nm^2。动态表面张力参数n值分别为0.85、0.74,t*分别为1.05和0.27 s,R1/2分别为14.11和69.79 m N/m/s,R=14的双子表面活性剂的动态表面张力优于R=12时。该季铵盐双子表面活性剂与结构相似的季铵盐表面活性剂如十六烷基三甲基溴化铵(CTAB)相比CMC低2个数量级。

Cationic gemini surfactants was synthesized directly from 1,4-bis-（ chloromethyl）-benzene（ XDC）,N,N-dimethyldodecylamine and N,N-dimethyltetradecylamine. In order to obtain optimal reaction conditions,orthogonal experiment was conducted. The optimal reaction conditions were performed with the molar ratio of amine and XDC 2. 4∶1 at 75 ℃ for 2 h. The chemical structure of the purified product was confirmed by FTIR,1HNMR and13 CNMR. The aqueous solution surface activity properties were studied and the results showed that when the length of carbon chain are 12 and 14,the surface tension（ γCMC） are 40. 71 and 35. 37 m N/m,critical micellar concentration（ CMC） are 1. 36×10^-5 and 2. 56 × 10^-6mol / L,p C20 are 5. 63 and 6. 18,excess adsorption amounts（ Γmax） are 2. 41× 10^-6and 3. 09 × 10^-6 mol / m^2,the saturation adsorption areas permolecule（ Amin） are 0. 69 and0. 54 nm^2. The parameters of dynamic surface tension（ DST） were n = 0. 85 and 0. 74,t＊= 1. 05 and0. 27 s,R1 /2= 14. 11 and 69. 79 m N / m / s respectively. The dynamic surface activity of surfactant withR = 14 is better than R = 12. The CMC of the Gemini surfactants are only one percent of the similar quaternary ammonium salt surfactant such as CTAB.