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Spontaneous Vesicle Formation and Spontaneous Vesicle-Micelle Transition

自发囊泡形成和自发囊泡-胶束转变

基本信息

批准号：
10440210
负责人：
ARATONO Makoto
金额：
$ 6.34万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

1. The phase behavior of a very dilute aqueous solution of a sodium dodecyl sulfate (SDeS)-decyltrimethylammonium bromide (DeTAB) mixture was investigated by the surface tension measuremnt an partly by the density measurement. The surface tension and density were measured as functions of total molality of surfactant m and composition of DeTAB, X.Break points were observed on the curves and identified as the critical vesicle concentration and the concentration of the initial and final points of the vesicle-micelle coexisting region, respectively. These break points were plotted against X, analyzed thermodynamically, and then the compared with the ones in the diagrams predicted from a simple model. The composition of DeTAB in the vesicle at the critical vesicle concentration, CVC, was obtained from the CVC vs X curve, and it was found out to be 0.5 at almost X values. From the other break point versus X plots, the composition region of the vesicle-micelle coexistence in the phase diagram was suggested to be from 0.62 to 0.65. Furthermore, vesicle formation was clearly indicated to take place even at X=0.9999, and therefore, the vesicle-micelle transition on the critical aggregation concentration versus X curve was expected to sit between X=0.9999 and 1.2. The surface tension of aqueous solution of decyltrimethylammonium decyl sulfate (DeTADeS) was measured as a function of temperature at various molalities under atmospheric pressure. DeTADeS has been found to form equilibrium multilamellar vesicles spontaneously. The surface density, the entropies of adsorption and the entropy of vesicle formation are evaluated. The mechanism of formation of equilibrium vesicle is investigated from the standpoint of thermodynamics and from the comparison of the results with those of the micelle forming systems.

1.用表面张力法和部分密度法研究了十二烷基硫酸钠(SDeS)-溴化十一烷基三甲基铵(DeTAB)混合溶液的相行为。测定了表面活性剂m的总摩尔分数和DeTAB、X组成对表面张力和密度的影响。在曲线上观察到突破点，分别为临界囊泡浓度和囊泡-胶束共存区域的起始点和终止点的浓度。这些断点被绘制成与X的关系图，进行热力学分析，然后与从简单模型预测的图表中的断点进行比较。从CVC-X曲线可以得到临界囊泡浓度CVC时囊泡中DeTAB的组成，在几乎X值时为0.5。从另一个转折点与X图的关系来看，相图中囊泡-胶束共存的组成区域为0.62-0.65。此外，即使在X=0.9999也清楚地表明了囊泡的形成，因此，临界聚集浓度-X曲线上的囊泡-胶束转变应该位于X=0.9999到1.2时。在常压条件下，测定了不同摩尔分数的十二烷基三甲基硫酸铵(DeTADeS)水溶液的表面张力。DeTADES被发现能自发形成平衡的多层囊泡。计算了膜的表面密度、吸附熵和囊泡形成熵。从热力学的角度并与胶束形成体系的结果进行了比较，对平衡囊泡的形成机理进行了探讨。