CTAB反相微乳液中水辛烷分子的自扩散研究

利用电导测量确定了CTAB/正丁醇/正辛烷/水四组分体系的相态，在反相微乳液区有明显的渗滤现象，通过脉冲梯度场核磁共振方法研究了反相微乳液中水和辛烷分子的自扩散行为，采用双指数拟合得出辛烷的自扩散系数。对于体系中出现的渗滤现象以及水和辛烷分子自扩散系数反常的原因，从分子水平上进行了解释。水和自扩散系数(2～7×10^-10m·s^-1)比一般文献值高，其原因：一是水在油相中有较大的溶解度；二是渗滤现象的存在，由于液滴间相互作用的增强和：粘性“碰撞而导致液滴的融合，以及由此而形成的瞬时水相连续通道，使水的自扩散系数增大。而辛烷自扩散系数比一般文献值小，则是由于在微乳液液滴的栅栏中表面活性剂分子烃链与辛烷分子间范德华引力所造成。

Self -diffusion study of solvent molecules in CTAB inverse microemulsion

Quaternary inverse microemulsion of a cationic surfactant (cetyltrimethylammonium bromide, CTAB), octane, waterm and 1- butanol has been investigated by using conductivity, pulsed foeld fradient spinechol NMR measurements. The conductivity behavior of such microemulstions has a distinct percolative phenomenon. In the W/O microemulsion region, the self -diffusion coefficient of water is relatively high(2～7×10^-10m·s^-1) due to higher solubility of water in the continuous phase, which is composed of octane (ω= 10%) and 1-butanol (an apolar solvent and a weak polar solvent ), and "sticky" collisions between the droplets tn the percolation rane. Pentration of a large amount of octane molecules between surfactants chanis singnificantly lowers (1～3×10^-10m^2·s^-1) the self- diffusion coefficient of octane .