A new oscillating bubble technique for measuring surface dilational properties
A new oscillating bubble technique for measuring surface dilational properties
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DOI：
10.1016/0927-7757(96)03561-3
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发表时间：
1996-08-20
影响因子：
5.2
通讯作者：
Wantke, KD
中科院分区：
文献类型：
--
作者：
Fruhner, H;Wantke, KD
研制了一种新型的振荡气泡装置，并用于测量表面活性剂、蛋白质和表面活性剂/蛋白质吸附层在1-300 Hz频率范围内的表面扩张性质。在一个封闭的测量室内，一个小的半球形气泡在毛细管的尖端产生。压电驱动器产生气泡体积的正弦振荡，并因此产生表面积和半径的变化。压电驱动器还可以产生任意的面积变化。这种方法允许测量由于半径和表面张力的变化而引起的弯曲气泡表面的压力差。压力振幅由安装在腔室底部的敏感压力传感器监测。人们可以从泵送体积中获得关于变形的信息，从压力幅值中获得关于表面张力变化的信息，从频率中获得关于变形速率的信息，以及关于变形和表面张力之间的相位角Phi的信息。十六烷基三甲基溴化铵溶液的扩张弹性随频率变化的实验结果与扩散交换理论符合得很好。明胶表现为几乎不溶的层;在所研究的频率间隔中没有观察到频率依赖性。混合明胶/阴离子表面活性剂吸附层在50-300 Hz的频率范围内显示出几乎线性的Δ γ（f）依赖性。应力振幅（Δ γ）随变形速率的增加是特性粘度的特征。
A new oscillating bubble device has been developed and used for measuring the surface dilational properties of surfactant, protein and surfactant/protein adsorption layers in the frequency range 1-300 Hz. Within a closed measuring chamber, a small hemispherical bubble is produced at the tip of a capillary. A piezoelectric driver generates sinusoidal oscillations of the bubble volume, and consequently produces changes in the surface area and the radius. The piezoelectric driver can also produce arbitrary changes of area.This method allows the measurement of the pressure difference across the curved bubble surface, due to changes in the radius and surface tension. The pressure amplitudes are monitored by a sensitive pressure transducer which is mounted at the bottom of the chamber. One obtains information on the deformation from the pumped volume, on the change in surface tension from the pressure amplitudes, on the rate of deformation from the frequency and on the phase angle Phi between deformation and surface tension.This novel technique can also be used for adsorption kinetics studies at the air/water and oil/water interfaces. Experimental results on the frequency dependence of the dilational elasticity of cetyltrimethylammonium bromide solutions are in good agreement with a diffusional exchange of matter theory. Gelatin behaves as an almost insoluble layer; no frequency dependence was observed in the studied frequency interval. A mixed gelatin/anionic surfactant adsorption layer shows an almost linear dependence of Delta gamma(f) in the frequency range 50-300 Hz. This increase in the stress amplitude (Delta gamma) with the deformation rate is a characteristic feature of an intrinsic viscosity.