Hypothesis

Interfacial rheology provides insight into the mechanical properties of adsorption layers on liquid-liquid interfaces, which mediates the stability of emulsion droplets. The use of capsule compression at the scale of an emulsion droplet to probe the interfacial rheology may open up the possibility of testing the interfacial rheological properties of droplets with complex histories and extremely small volumes found in many applications.

Experiments

The time dependent interfacial rheological behavior of β-lactoglobulin adsorption layers on an oil/water interface in the native and crosslinked state was extracted using small oscillatory indentation with atomic force microscopy (AFM). The results of this novel model and experimental approach were compared to the well-established techniques of interfacial shear rheology (ISR) and dilational pendant drop tensiometry that were performed on analogous interfaces.

Findings

The tan δ measured between the ISR and AFM measurements provide similar results in an overlapping frequency range, but the viscoelastic moduli G’ and G’’ differ by several orders of magnitude. This is most likely the result of the different flow fields and the low deformation of the AFM measurements compared to dilational and shear flow fields.

中文翻译：

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β-乳球蛋白在微滴压缩，界面扩张和剪切流变学上在乳滴上的交联的粘弹性表征

假设

界面流变学深入了解了液-液界面上吸附层的机械性能，介导了乳液液滴的稳定性。在乳液液滴的尺度上使用胶囊压缩来探测界面流变性可能为测试具有多种应用的复杂历史和极小体积的液滴的界面流变性提供了可能性。

实验

使用原子力显微镜（AFM）的小型振荡压痕，提取了天然和交联状态下油/水界面上β-乳球蛋白吸附层随时间的界面流变行为。将该新型模型和实验方法的结果与在类似界面上进行的成熟的界面剪切流变学（ISR）和膨胀悬垂滴定法进行了比较。

发现

在ISR和AFM测量之间测得的tanδ在重叠的频率范围内提供了相似的结果，但粘弹性模量G'和G''相差几个数量级。与膨胀流场和剪切流场相比，这很可能是不同流场和AFM测量的低变形的结果。