Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128 Mainz, Germany.
Soft Matter. 2016 Dec 21;13(1):222-229. doi: 10.1039/c6sm00766j.
The self-assembly of amphiphilic Janus colloids in microfluidic channels is studied using hybrid molecular dynamics simulations with fully resolved hydrodynamic interactions incorporated through the multi-particle collision dynamics algorithm. The simulations are conducted at a density and temperature where the Janus particles spontaneously self-assemble into spherical micelles to minimize the interface between the solvophobic caps and the surrounding solvent. In confined systems, this contact area can also be reduced by aggregation at the channel walls. Indeed, a sizable fraction of free particles and small clusters with three and four members are found at the walls when the microfluidic channel is made up of a comparably solvophobic material as the Janus colloids. When the applied Poiseuille flow is sufficiently strong, the colloidal micelles break up into smaller fragments and isolated particles. However, at intermediate flow rates the shear-induced dissociation and reorganization of aggregates lead to a net growth of the micelles with a sizable amount of particles in icosahedral clusters with 13 particles. Furthermore, the parabolic velocity profile of the flow causes a highly non-uniform cluster size distribution between the channel walls, where the aggregation number decreases close to the walls.
使用混合分子动力学模拟研究了在微流道中两亲性 Janus 胶体的自组装，其中通过多粒子碰撞动力学算法完全解决了流体动力学相互作用。模拟在密度和温度下进行，其中 Janus 粒子自发自组装成球形胶束，以最小化疏溶剂帽与周围溶剂之间的界面。在受限系统中，通过在通道壁处聚集也可以减小接触面积。实际上，当微流体通道由与 Janus 胶体相比具有相当疏溶剂性的材料组成时，在壁处发现相当一部分自由粒子和具有三个和四个成员的小簇。当施加的泊肃叶流足够强时，胶体胶束会分解成较小的片段和孤立的粒子。然而，在中等流速下，剪切诱导的聚集物的解离和重组导致胶束的净增长，其中具有 13 个粒子的二十面体簇中有相当数量的粒子。此外，流动的抛物线速度分布导致通道壁之间的团聚体尺寸分布非常不均匀，其中在靠近壁处聚集数减小。
