Aggregation Behavior of Nitrophenoxy-Tailed Quaternary Ammonium Surfactants

详细信息    查看全文

• 作者：Xu Huang ; Yuchun Han ; Yingxiong Wang ; Yilin Wang
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：November 1, 2007
• 年：2007
• 卷：111
• 期：43
• 页码：12439 - 12446
• 全文大小：251K
• 年卷期：v.111,no.43(November 1, 2007)
• ISSN：1520-5207

文摘

Cationic surfactants N,N,N-trimethyl-10-(4-nitrophenoxy)decylammonium bromide (N10TAB) and N,N,N',N'-tetramethyl-N,N'-bis[10-(4-nitrophenoxy)decyl]-1,6-hexanediammonium dibromide (N10-6-10N), bearingaromatic nitrophenoxy groups in the ends of their hydrophobic chains, have been synthesized, and their self-assembling properties in aqueous solutions have been studied by conductivity, isothermal titration microcalorimetry, ¹H NMR spectroscopy, and dynamic light scattering. Below the critical micelle concentration,N10-6-10N can form premicelles with 2 or 3 surfactant molecules. Beyond the critical micelle concentration,the two surfactants have strong self-aggregation ability and can form micelles of rather small size and withsmall aggregation numbers N, which are 30 ± 3 for N10TAB and 20 ± 2 for N10-6-10N, respectively. Also,the variations in ¹H NMR signals at different surfactant concentrations provide the information on theenvironmental change of the surfactants upon their micellization progress. The most prominent phenomenonis the shielding effect of the aromatic groups over the protons in the aliphatic chains, implying that thenitrophenoxy groups partially insert into the micelles and face the several middle methylenes of the hydrophobicside chains.