Generation and manipulation of bubbles and foams stabilised by magnetic nanoparticles
Generation and manipulation of bubbles and foams stabilised by magnetic nanoparticles
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DOI：
10.1016/j.colsurfa.2011.04.029
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发表时间：
2011-07
期刊：
影响因子：
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通讯作者：
J. Rodrigues;E. Rio;J. Bobroff;D. Langevin;W. Drenckhan
中科院分区：
文献类型：
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作者：
J. Rodrigues;E. Rio;J. Bobroff;D. Langevin;W. Drenckhan
目前，人们对技术的发展非常感兴趣，这些技术不仅使液体泡沫超稳定，而且对非接触刺激也有反应。这两个目标都可以通过应用磁性颗粒作为稳定剂来同时满足，这不仅抑制了泡沫的传统老化机制（例如聚结和粗化），而且还提供了通过施加磁场进行非接触操作和表征的手段。本着这一精神，我们在此提供了对商用MAGSILICA®H8纳米颗粒的详细研究，该纳米颗粒由二氧化硅壳包围的单畴氧化铁组成，用于产生超稳定气泡和泡沫，并研究它们对各种类型磁场的响应。更具体地说，我们研究了疏水磁性颗粒在水/乙醇混合物中的发泡行为，我们确认，最好的发泡行为是实现中间润湿性的颗粒。我们研究了这些泡沫的磁化强度，并使用磁场梯度不仅验证了气泡的超稳定性，而且还证明了它们的磁操纵的容易性。这两种测量为我们提供了更详细的信息，颗粒分离力和在气/液界面处的聚集颗粒的厚壳的存在。最后但并非最不重要的是，我们演示了如何可以方便地加热，并保持在良好的控制温度，通过应用振荡磁场这样的泡沫。
Much interest is being given these days to the development of techniques, which render liquid foams not only super-stable, but also responsive to non-contact stimulation. Both of these goals can be met simultaneously by the application of magnetic particles as stabilising agents, which not only suppress the traditional ageing mechanisms of foams (such as coalescence and coarsening), but also provide means of non-contact manipulation and characterisation by the application of magnetic fields. In this spirit we provide here detailed investigations into the use of commercially available MAGSILICA®H8 nanoparticles, which consist of single-domain iron oxides surrounded by a silica shell, for the generation of super-stable bubbles and foams, and study their response to various types of magnetic fields. More specifically, we investigate the foaming behaviour of hydrophobic magnetic particles in water/ethanol mixtures for which we confirm that best foaming behaviour is achieved for intermediate wettabilities of the particles. We characterise the magnetisation of these foams and use magnetic field gradients to not only validate the super-stability of bubbles, but also to demonstrate the ease of their magnetic manipulation. Both kinds of measurements provide us with more detailed information on particle-detachment forces and the presence of a thick shell of aggregated particles at the gas/liquid interface. Last but not least, we demonstrate how such foams may conveniently be heated and kept at well-controlled temperatures through the application of oscillating magnetic fields.