Johannes-Gutenberg-Universität Mainz Institut für Physik, 55099 Mainz, Germany.
Phys Chem Chem Phys. 2011 Mar 7;13(9):4109-18. doi: 10.1039/c0cp01912g. Epub 2011 Jan 13.
Electrostatic interactions between charged, distant colloids in a bulk electrolyte solution do not depend on the inherent structure of ions and a solvent forming a double layer. For charged colloids trapped at an interface between an electrolyte and air this no longer holds; as the electrostatic interactions are mediated via air and the field lines determining the interactions originate at the charged surface, these details come into prominence. Using the Langevin-Poisson-Boltzmann equation we investigate how steric effects and the polarization saturation of a solvent effect the contact potential at the colloid surface and, in consequence, the long range interactions between colloids trapped at an interface. For a surface charge 0.4 C m(-2) the combination of these effects can increase the interactions by up to ∼40 times when compared to Poisson-Boltzmann calculations. The validity of these enhancement mechanisms is supported by recent experimental data (K. Masschaele et al., Phys. Rev. Lett., 2010, 105, 048303).
在电解质溶液中，带电荷的胶体颗粒之间的静电相互作用不依赖于形成双电层的离子和溶剂的固有结构。对于被困在电解质和空气界面之间的带电胶体，情况不再如此；由于静电相互作用是通过空气介导的，并且决定相互作用的场线起源于带电表面，因此这些细节变得突出。我们使用朗之万-泊松-玻尔兹曼方程研究了空间位阻效应和溶剂的极化饱和如何影响胶体表面的接触电势，从而影响被困在界面处的胶体之间的长程相互作用。对于表面电荷为 0.4 C m(-2)，与泊松-玻尔兹曼计算相比，这些效应的组合可以使相互作用增加高达约 40 倍。这些增强机制的有效性得到了最近实验数据的支持（K. Masschaele 等人，Phys. Rev. Lett.，2010，105，048303）。
