Long-Ranged Oppositely Charged Interactions for Designing New Types of Colloidal Clusters
Long-Ranged Oppositely Charged Interactions for Designing New Types of Colloidal Clusters
复制标题
DOI：
10.1103/physrevx.5.021012
复制
发表时间：
2015-04-29
影响因子：
12.5
通讯作者：
van Blaaderen, Alfons
中科院分区：
文献类型：
--
作者：
Demirors, Ahmet Faik;Stiefelhagen, Johan C. P.;van Blaaderen, Alfons
控制胶体的价态并不是一件容易的事，也是胶体领域长期追求的目标。通常，调整胶体粒子的首选邻居数量需要定向结合，就像片状粒子的情况一样，这在实验上很难实现。在这里，我们展示了一种通用的方法来创建分子和其他新的规则胶体簇的胶体类似物，而不使用片状或复杂的键合方案(例如，DNA涂层)，方法是使用相反电荷粒子之间的长程吸引和排斥作用的组合，这也使得规则粒子簇不都是紧密接触的。我们发现，由于相互吸引和排斥的相互作用，分散在介电常数为4和10的相反带电粒子为形成二元胶体团簇提供了一种可行的途径。通过调节颗粒的大小、比例和相互作用，可以控制生成的规则胶体团的类型和形状。最后，我们给出了一个由带负电荷的大卫星粒子和带正电荷的小卫星粒子组成的星团的例子，对于这种星团，静电性质和相互作用可以通过电场来改变。看起来，对于足够强的磁场，卫星粒子可以在宿主粒子的表面上移动，并使星团极化。对于更强的磁场，卫星粒子可以完全被拉出，扭转星系团上的净电荷。通过计算机模拟，我们研究了带电粒子如何在相反带电球体上分布以最小化它们的能量，并将结果与著名的Thomson问题的解进行了比较。我们还用模拟方法研究了这种团簇对德拜屏蔽长度kappa(-1)和粒子上电荷比的依赖关系，与实验观测结果符合得很好。
Getting control over the valency of colloids is not trivial and has been a long-desired goal for the colloidal domain. Typically, tuning the preferred number of neighbors for colloidal particles requires directional bonding, as in the case of patchy particles, which is difficult to realize experimentally. Here, we demonstrate a general method for creating the colloidal analogs of molecules and other new regular colloidal clusters without using patchiness or complex bonding schemes (e.g., DNA coating) by using a combination of long-ranged attractive and repulsive interactions between oppositely charged particles that also enable regular clusters of particles not all in close contact. We show that, due to the interplay between their attractions and repulsions, oppositely charged particles dispersed in an intermediate dielectric constant (4 < epsilon < 10) provide a viable approach for the formation of binary colloidal clusters. Tuning the size ratio and interactions of the particles enables control of the type and shape of the resulting regular colloidal clusters. Finally, we present an example of clusters made up of negatively charged large and positively charged small satellite particles, for which the electrostatic properties and interactions can be changed with an electric field. It appears that for sufficiently strong fields the satellite particles can move over the surface of the host particles and polarize the clusters. For even stronger fields, the satellite particles can be completely pulled off, reversing the net charge on the cluster. With computer simulations, we investigate how charged particles distribute on an oppositely charged sphere to minimize their energy and compare the results with the solutions to the well-known Thomson problem. We also use the simulations to explore the dependence of such clusters on Debye screening length kappa(-1) and the ratio of charges on the particles, showing good agreement with experimental observations.