Phase behavior of a DNA-based surfactant mixed with water and n-alcohols.
Phase behavior of a DNA-based surfactant mixed with water and n-alcohols.
复制标题
基于 DNA 的表面活性剂与水和正醇混合的相行为。
DOI：
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发表时间：
2006
影响因子：
3.3
通讯作者：
B. Lindman
中科院分区：
文献类型：
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作者：
C. Leal;A. Bilalov;B. Lindman
研究了以DNA为反离子的阳离子表面活性剂十二烷基三甲基铵(DTA)在水和正醇(正十二醇、正辛醇、正己醇、正丁醇和乙醇)混合物中的自组装行为。建立了相图，并用(2)H-核磁共振、小角X射线散射(SAXS)等技术对相图的不同区域进行了表征。DNA-DTA表面活性剂可溶于所有所研究的醇，表现出从癸醇到乙醇的溶解度增加。所有相图在液晶区的出现方面都是相似的，但液晶区的面积随着从癸醇到乙醇的增加而增加。在所有相图中，富醇一侧的六方相(反转型)和另一侧的片层相被检测到。对于平衡比例的组分，存在层状相和六方相共存，在这里用双四极分裂在(2)H核磁共振谱中检测到。沿联络线分裂幅度几乎保持不变的事实证实了相图的正确性。除乙醇外，所有的醇都作为助表面活性剂穿透DNA-DTA膜。在三元混合物中加入盐会导致片状和六方相的晶胞尺寸增大。当丁醇用于酒精相时，相图变得更加复杂。这里，出现了一种新的各向同性相，其某些性质类似于简单表面活性剂体系得到的无序海绵(L3)相。
The self-assembly behavior of a cationic surfactant (dodecyltrimethylammonium, DTA) with DNA as counterion in mixtures of water and n-alcohols (decanol, octanol, hexanol, butanol, and ethanol) was investigated. The phase diagrams were established and the different regions of the phase diagram characterized with respect to microstructure by (2)H NMR, small-angle X-ray scattering (SAXS), and other techniques. The DNA-DTA surfactant is soluble in all of the studied alcohols, showing increased solubility from decanol down to ethanol. All of the phase diagrams are analogous with respect to the occurrence of liquid crystalline (LC) regions, but the area of the LC region increases as one goes from decanol to ethanol. In all phase diagrams, hexagonal phases (of the reversed type) for the alcohol-rich side and lamellar phases for the other side were detected. For balanced proportions of the components, there is a coexistence of the lamellar and the hexagonal phase, here detected with a double quadrupole splitting in the (2)H NMR spectra. The correctness of the phase diagrams is confirmed by the fact that along the tie-lines the splitting magnitude remains nearly constant. All of the alcohols except for ethanol act as cosurfactants penetrating the DNA-DTA film. Adding salt to the ternary mixtures causes an increase in the unit cell dimension of the lamellar and the hexagonal phases. The phase diagram becomes more complicated when butanol is used for the alcohol phase. Here, there is the occurrence of a new isotropic phase with some properties analogous to those of the disordered sponge (L3) phase obtained for simple surfactant systems.