Effect of Hydrophobic Chain Structure on Phase Transition and Domain Formation of Hybrid Alcohol Films Adsorbed at the Hexane/Water Interface
Effect of Hydrophobic Chain Structure on Phase Transition and Domain Formation of Hybrid Alcohol Films Adsorbed at the Hexane/Water Interface
复制标题
疏水链结构对己烷/水界面吸附杂化醇膜相变和域形成的影响
DOI：
10.1021/acs.jpcb.5b07632
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发表时间：
2015
期刊：
影响因子：
3.3
通讯作者：
T. Takiue
中科院分区：
文献类型：
--
作者：
K. Mitani;Y. Imai;T. Ina;K. Nitta;H. Tanida;T. Uruga;H. Matsubara;M. Aratono;T. Takiue
用界面张力法和x射线反射法研究了两种杂化醇(CF3（CF2)m-1(CH2)nOH, FmHnOH）、2-全氟辛基乙醇（F8H2OH）和2-全氟己基己醇（F6H6OH）作为混合物在己烷/水界面上的相变和畴形成。纯F8H2OH的界面张力γ -总摩尔浓度曲线在高浓度时有一个断点，因此，在高界面压力π下，每分子平均面积不连续变化，对应于膨胀膜和凝聚膜之间的相变。利用非相干干涉域模型对展开态的菲涅耳分割反射率yr / rfversusqz图进行拟合，确定界面覆盖率，即界面被凝聚相覆盖的比例。这表明膨胀膜是不均匀的，由一个凝聚的F8H2OH结构域组成，其尺寸大于x射线相干长度（~ 5 μm）。在混合体系中，随着混合物中f6h6ohx2体积成分的增加，相变点处的数值不连续变化变小，最终呈连续变化；即当x2≥0.6时，相变变得模糊。这种行为与x2的界面覆盖率增加有关。利用相干干涉域模型拟合theR/RFversusQzplot，表明相干干涉域的尺寸小于5 μm。这些结果可能是由于F6H6OH在F8H2OH畴边界的优先吸附降低了畴线张力。
The phase transition and domain formation of the adsorbed film of two kinds of hybrid alcohols (CF3(CF2)m-1(CH2)nOH, FmHnOH), 2-perfluorooctylethanol (F8H2OH) and 2-perfluorohexylhexanol (F6H6OH), as a mixture at the hexane/water interface was investigated by interfacial tensiometry and X-ray reflection. The interfacial tension γ versus total molalitymcurve of pure F8H2OH has a break point at high concentration, and thus, the mean area per moleculeAchanges discontinuously at high interfacial pressure π, corresponding to the phase transition between expanded and condensed films. The Fresnel divided reflectivityR/RFversusQzplots in the expanded state was well-fitted by the domain model for incoherent interference to determine the interfacial coverage, which is the fraction of the interface covered by the condensed phase. This indicates that the expanded film is heterogeneous and consists of a condensed F8H2OH domain, the size of which is larger than the X-ray coherence length (∼5 μm). In the mixed system, the discontinuous change inAat the phase transition point becomes small with increasing the bulk composition of F6H6OHX2in the mixture, and eventually theAvalue changes continuously; i.e, the phase transition becomes obscure inX2≥ 0.6. This behavior was linked to an increase in interfacial coverage withX2. Furthermore, theR/RFversusQzplot was fitted by the domain model for coherent interference, suggesting that the size of the domain is smaller than 5 μm. These results are probably due to the reduction of domain line tension by preferential adsorption of F6H6OH at the F8H2OH domain boundary.