Spontaneous Vesicle Formation and Spontaneous Vesicle-Micelle Transition

1.用表面张力法和密度法研究了十二烷基硫酸钠（SDeS）-癸基三甲基溴化铵（DeTAB）混合物的稀水溶液的相行为。的表面张力和密度的表面活性剂m和组合物的DeTAB，X的总摩尔浓度的函数进行测量。断点上观察到的曲线，并确定为临界囊泡浓度和囊泡胶束共存区域的初始和最终点的浓度，分别。将这些断裂点与X作图，进行几何分析，然后与从简单模型预测的图中的断裂点进行比较。从临界囊泡浓度CVC对X曲线获得囊泡中DeTAB的组成，并且发现在几乎X值处其为0.5。从另一个断点与X曲线，在相图中的囊泡-胶束共存的组合物区域被建议为从0.62到0.65。此外，清楚地表明即使在X=0.9999时也会发生囊泡形成，因此，预期临界聚集浓度对X曲线上的囊泡-胶束转变位于X=0.9999和1.2之间。在常压下，测定了不同摩尔浓度下癸基三甲基硫酸铵（DeTADeS）水溶液的表面张力与温度的关系。已发现DeTADeS自发形成平衡多层囊泡。的表面密度，吸附熵和泡形成的熵进行了评估。从热力学的角度，并通过与胶束形成体系的比较，探讨了平衡囊泡的形成机理。

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.