蠕虫状胶束溶液组成对其黏弹性影响

Effects of the composition of worm-like micellar solutions on the viscoelasticity

用阳离子表面活性剂十八烷基三甲基溴化铵(STAB)作为主剂,水杨酸钠(NaSal)/碳酸钠(Na_2CO_3)、油酸钠(NaOA)作为助剂,制备蠕虫状胶束溶液,研究组分摩尔比及助剂种类对蠕虫状胶束流变特性的影响。结果表明,溶液总质量分数为3.3%,STAB与助剂摩尔比R在2.2~2.6时,两个体系均形成了蠕虫状胶束。助剂为NaSal/Na_2CO_3,R=2.4时体系形成的胶束最长;助剂为NaOA,R=2.6时体系形成的胶束最长,数目最多。摩尔比相同时,STAB/NaOA溶液黏弹性更好。由溶液的实际模量所得Cole-Cole图在低频及中频时为半圆形,说明所制备的2种溶液均为符合麦克斯韦模型的黏弹性流体。

Wormlike micelles were prepared by mixing octadecyltrimethylammonium bromide （STAB） with sodium salicylate/sodium carbonate （NaSal/Na2CO3） or sodium oleate （NaOA）. The effects of molar ratio and the type of additives on the rheological behavior of worm-like micelles were studied. The results showed that, when the total mass fraction was 3.3% and the molar ratio of STAB/additive was between 2.2 and 2.6, both the two systems formed worm-like micelles. In the case of NaSal/Na2CO3 as additive, when the molar ratio of STAB/additive was 2.4, the system formed the longest micelles. When the additives was NaOA and the molar ratio of STAB/ additive was 2.6, the system formed the longest micelles with the largest number. For the same molar ratio, the system of STAB/NaOA showed better viscoelasticity. The cole-cole plot from the actual modulus was a semmicircle in the low frequency and intermediate frequency, indicating that both the two systems fit the Maxwell＇s mechanical model as viscoelastic fluid.