Abdel-Rahem R, Hoffmann H
Al Ahsa Teachers College, Department of Science, Section of Chemistry, Al Hafouf 31982, Saudi Arabia.
J Colloid Interface Sci. 2007 Aug 1;312(1):146-55. doi: 10.1016/j.jcis.2006.09.023. Epub 2006 Sep 16.
In continuation of our previous investigations on the aqueous phase behavior of cetyltrimethylammonium 2-hydroxy-1-carboxy-naphthoate (CTA-2,1-HCN) (see J. Colloid Interface Sci. 288 (2005) 570), we have studied the phase behavior and the properties of the phases of the two shorter homologues, C(14)TA-2,1-HCN and C(12)TA-2,1-HCN. The phases were prepared from the alkyltrimethylammonium hydroxides RTAOH and the naphtholcarboxylic acid. By preparing the systems in this way the surfactant solutions contain no excess salt. With increasing counter-ion-surfactant ratio r we observed the same sequence of phases as for the previously studied C(16)-system, namely a L(1)-phase and a L(alpha)-phase with multilamellar vesicles (MLV). The single phases are separated by a two-phase L(1)/L(alpha) region. The phases were characterized with FF-TEM, rheological and SANS measurements. For both systems the viscosity of the L(1)-phases passes with increasing counter-ion/surfactant ratio over a maximum. The height of the maximum decreases strongly with decreasing chain length while the complex viscosity of the MLV-phase depends little on the chain length. For 100 mM solution both MLV phases behave like a weak gel and have a yield stress value. It is thus shown that it is possible to prepare viscoelastic surfactant solutions with a yield stress value from single chain surfactants with a dodecyl chain.
在我们之前对十六烷基三甲基铵2-羟基-1-羧基萘（CTA-2,1-HCN）水相行为的研究（见《胶体与界面科学杂志》288 (2005) 570）的延续中，我们研究了两种较短同系物C(14)TA-2,1-HCN和C(12)TA-2,1-HCN的相行为及相的性质。这些相是由烷基三甲基氢氧化铵RTAOH和萘酚羧酸制备而成的。通过这种方式制备体系，表面活性剂溶液中不含有过量的盐。随着抗衡离子 - 表面活性剂比率r的增加，我们观察到与之前研究的C(16)体系相同的相序列，即一个L(1)相和一个带有多层囊泡（MLV）的L(α)相。单相由一个两相L(1)/L(α)区域分隔开。通过FF-TEM、流变学和小角中子散射测量对这些相进行了表征。对于这两个体系，L(1)相的粘度随着抗衡离子/表面活性剂比率的增加先达到一个最大值然后下降。最大值的高度随着链长的减小而强烈降低，而MLV相的复数粘度对链长的依赖性很小。对于100 mM的溶液，两个MLV相都表现得像弱凝胶并且具有屈服应力值。因此表明，有可能用具有十二烷基链的单链表面活性剂制备出具有屈服应力值的粘弹性表面活性剂溶液。
