Stripes of partially fluorinated alkyl chains: dipolar Langmuir monolayers.
Stripes of partially fluorinated alkyl chains: dipolar Langmuir monolayers.
复制标题
部分氟化烷基链的条纹：偶极朗缪尔单层。
DOI：
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发表时间：
2005
影响因子：
4.4
通讯作者：
Motomu Tanaka
中科院分区：
文献类型：
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作者：
Matthias F. Schneider;D. Andelman;Motomu Tanaka
在气液相共存条件下，观察到表面活性剂与部分氟化脂锚（F-烷基脂）形成的朗缪尔单分子膜的带状区域。通过荧光显微镜测量的条纹的平均周期性在微米范围内，在2和8微米之间变化。由于末端- CF（3）基团之间的偶极-偶极相互作用，所观察到的带状图案是稳定的。由于周围介质（空气）的介电常数较低，与非氟化脂质相比，这些相互作用特别强。这些长程偶极相互作用倾向于延长畴，与倾向于使畴边界的长度最小化的线张力相反。这种行为应该与具有烷基链的脂质单层的行为进行比较，并且其在气液共存时形成球形微区（气泡）。测量的条纹周期性同意定量与理论模型。此外，如预期的那样，通过添加痕量（0.1摩尔%）胆固醇导致线张力的降低，导致域周期性的降低。
Stripelike domains of Langmuir monolayers formed by surfactants with partially fluorinated lipid anchors (F-alkyl lipids) are observed at the gas-liquid phase coexistence. The average periodicity of the stripes, measured by fluorescence microscopy, is in the micrometer range, varying between 2 and 8 microm. The observed stripelike patterns are stabilized due to dipole-dipole interactions between terminal- CF(3) groups. These interactions are particularly strong as compared with nonfluorinated lipids due to the low dielectric constant of the surrounding media (air). These long-range dipolar interactions tend to elongate the domains, in contrast to the line tension that tends to minimize the length of the domain boundary. This behavior should be compared with that of the lipid monolayer having alkyl chains, and which form spherical microdomains (bubbles) at the gas-liquid coexistence. The measured stripe periodicity agrees quantitatively with a theoretical model. Moreover, the reduction in line tension by adding traces (0.1 mol %) of cholesterol results, as expected, in a decrease in the domain periodicity.