Electric-Field-Induced Lock-and-Key Interactions between Colloidal Spheres and Bowls

To realize new and directed self-assembly (SA) pathways, the focus in colloid science and nanoscience has shifted from spherical particles and interactions to increasingly more complex shapes and interparticle potentials. This field is fueled by recent breakthroughs in particle synthesis, such as particles with complementary shapes that allow for specific lock-and-key interactions induced by depletants. Here, we show that electric fields form an alternative route for directing the SA of convex and concave colloids, with the additional advantage that the system now becomes switchable by external conditions. Both experimental and theoretical results are presented that validate the electric-field-induced assembly mechanism and show that even irreversibly bound composites can be generated by tuning the force balance. The successful isolation of the irreversible composite particles, in combination with generalization to different materials, shows that the current mechanism provides a versatile new path not only toward complex-particle synthesis but also toward directed self-assembly.为实现新型定向自组装（self-assembly, SA）路径，胶体科学与纳米科学领域的研究重心已从球形颗粒及粒子间相互作用，转向愈发复杂的颗粒形貌与粒子间势能。该领域的发展得益于颗粒合成技术的近期突破，例如具备互补形貌的颗粒可通过排空剂诱导产生特异性锁钥相互作用。本文证实电场可作为调控凸、凹胶体自组装的另一途径，其额外优势在于该体系可通过外部条件实现切换。本文同时呈现了验证电场诱导组装机制的实验与理论结果，并表明通过调控力平衡，甚至可生成不可逆结合的复合结构。成功分离不可逆复合颗粒，并将该机制拓展至不同材料体系，足以证明当前提出的机制不仅为复杂颗粒合成提供了通用新路径，亦为定向自组装开辟了全新方向。