Surface freezing and molecular miscibility of binary fluoroalkanol-alkanol liquid mixture
Surface freezing and molecular miscibility of binary fluoroalkanol-alkanol liquid mixture
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二元氟烷醇-烷醇液体混合物的表面冷冻和分子混溶性
DOI：
10.1016/j.colsurfa.2017.04.047
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
T. Takiue
中科院分区：
文献类型：
--
作者：
M. Tsuura;A. Shuto;S. Hiraki;Y. Imai;H. Sakamoto;M. Aratono;H. Tanida;K. Nitta;T. Uruga;T. Takiue
采用表面张力、外反射吸收红外光谱（ERA-FTIR）和X射线反射率（XR）研究了6-全氟己基己醇（F6 H6 OH）和1-十二醇（C12 OH）液体混合物的表面冻结（SF）。纯C_（12）OH液体的表面张力-温度曲线在表面液体（SL）-SF相变温度Ts处出现一个尖锐的折点。另一方面，纯F6 H6 OH的表面张力随着温度的升高而单调下降。在SF状态的C12 OH的表面形成的熵是大的负，由于在表面的有序结构。X射线衍射分析表明，C12 OH分子间通过水分子的插入，形成了由相互面对的羟基之间的氢键稳定的双分子层。在F6 H6 OH-C12 OH系统中，表面组成的估计表明，SL状态相比于本体液体富集F6 H6 OH。SL层中的负过剩熵表明，F6 H6 OH分子在表面形成域。此外，在SF状态下的表面组成和电子密度分布表明，少量的F6 H6 OH与C12 OH混合在SF双层中，其中F6 H6 OH分子优先存在于双层的上层。
The surface freezing (SF) of liquid 6-perfluorohexyl hexanol (F6H6OH)–1-dodecanol (C12OH) mixture was studied by surface tension, external reflection absorption FTIR (ERA-FTIR), and X-ray reflectivity (XR) measurements. The surface tension vs. temperature curve of pure C12OH liquid shows a sharp break point at the surface liquid (SL)–SF phase transition temperatureTs. The surface tension of pure F6H6OH, on the other hand, decreases monotonically with increasing temperature. The entropy of surface formation in the SF state of C12OH is large negative due to a well-ordered structure at the surface. The electron density profile determined by XR showed that the C12OH molecules form bilayer stabilized by the hydrogen bonding between hydroxyl groups facing each other through water molecule intercalated in between them. In the F6H6OH–C12OH system, the estimation of surface composition indicated that the SL state is enriched in F6H6OH compared to bulk liquid. The negative excess entropy in the SL layer suggests that F6H6OH molecules form domains at the surface. Furthermore, the surface composition and electron density profile in the SF state indicated that a small amount of F6H6OH mix with C12OH in the SF bilayer in which F6H6OH molecules preferentially exist in the upper layer of the bilayer.