连接基团链长度对季铵盐二聚表面活性剂C_(12)-s-C_(12)·2Br在水溶液中胶团化行为的影响

Effect of Spacer Chain Length on Aggregation of C_(12)-s-C_(12)·2Br Dimeric Surfactants in Aqueous Solutions

用电导法、稳态荧光法和粘度法研究了二聚表面活性剂 C1 2 -s-C1 2 · 2 Br分子中的连接基团链长度(s=2 ,3 ,4,6)对其在水溶液中聚集行为的影响 .实验发现 ,C1 2 -s-C1 2 · 2 Br的胶团生成能力远比其单体C1 2 TABr强得多 ,前者 cmc值较后者降低一个数量级 .胶团聚集数 N随表面活性剂浓度 c的增大而增大 ,其中当 s=2时的 N值在 c=7.7mmol/L后开始急剧增大 .计算结果表明 ,此时胶团形状发生了明显变化 ,形成了椭球形的胶团 .

Effect of spacer chain length on aggregation of C 12 s C 12 ·2Br dimeric surfactants in aqueous solutions has been investigated by using conductivity and viscosity measurements as well as steady fluorescence quench technique. The results showed the ability for the micelle formation of C 12 s C 12 ·2Br dimeric surfactants is much better than that of their monomer, dodecyltrimethylammonium bromide(C 12 TABr). The values of cmc for the former are lower than an order compared with the latter. The aggregation number N of C 12 s C 12 ·2Br micelles decreases with increasing concentration c , specially for s =2, the value of N increases rapidly at c >7 7 mmol/L. The calculated result indicates a significant change in the micellar shape and the formation of prolate ellipsoid micelles at c >7.7 mmol/L. The viscosity measurement for C 12 2 C 12 ·2Br micellar solutions demonstrates the calculated results.