双子表面活性剂DSDBS水溶液的表面特性

SURFACE PROPERTIES OF GEMINI SURFACTANT DSDBS IN AQUEOUS SOLUTION

采用表面张力法和电导率实验,结合冷冻刻蚀电镜观察等手段,研究了双子表面活性剂双十二烷基苯磺酸钠DSDBS-x(x为双子表面活性剂桥联基团的碳原子数,x为2和6)水溶液的表面特性。30℃下DSDBS-2和DSDBS-6的临界胶束浓度(CMC)分别为1.3×10-5和2.5×10-5mol/L,与对应单体十二烷基苯磺酸钠(SDBS)相比,胶束结构致密。当DSDBS浓度大于4倍CMC后,其水溶液电导率值偏离线性关系,为其胶束由球状胶束向棒状胶束转变所致。DSDBS-6的桥联基团碳链较长,且可以向界面弯曲,NaCl对其饱和吸附量(ΓCMC)的影响比对DSDBS-2的要大。

The surface properties of gemini surfactant aqueous solution, referred to as dimeric sodium dodecyl benzene sulfonate DSDBS-x, where x was the carbon numbers of the spacer （x=2 and 6）, were investigated by using the determinations of surface tension, conductivity and freeze-fracture-transmission-electron-microscopy （FF-TEM） method. It was found that the critical micelle concentration （CMC） at 30℃ for DSDBS-2 and DSDBS-6 were 1.3×10-5 and 2.5×10-5 mol/L, respectively, and their micelle structures were more compat than that of corresponding conventional monomer sodium dodecyl benzene sulfonate （SDBS）. With DSDBS concentration increased more than four times of its CMC, the solution conductivity deviated from the expected linear relationship as the consequence of spheroidal micelles transferring into rod-micelles. Furthermore, the influence of NaCl on the surface excess concentration （ΓCMC） of DSDBS-6 was stronger than that of DSDBS-2, owing to the former＇s longer carbon chain bending toward to interface easily.