Center for Bioinformatics, Saarland University, Saarbrücken, Germany.
Phys Rev Lett. 2012 Sep 21;109(12):128302. doi: 10.1103/PhysRevLett.109.128302. Epub 2012 Sep 17.
Crystalline and amorphous materials composed of the same atoms exhibit strikingly different properties. Likewise, the behavior of materials composed of mesoscale particles depends on the arrangement of their constituent particles. Here, we demonstrate control over particle arrangement during agglomeration. We obtain disordered and ordered agglomerates of the same alkyl thiol-coated gold nanoparticles depending on temperature and solvent. We find that ordered agglomeration occurs exclusively above the melting temperature of the ligand shells. Many-particle simulations show that the contact mechanics of the ligand shells dominate the order-disorder transition: Purely spherical particle-particle interactions yield order, whereas localized "stiction" between the ligand shells leads to disorder. This indicates that the "stickiness" and the packing of the agglomerates can be switched by the state of the ligand shells. It suggests that contact mechanics govern ordering in a wide range of nanoparticles.
由相同原子组成的晶态和非晶态材料表现出显著不同的性质。同样，由介观粒子组成的材料的行为取决于其组成粒子的排列。在这里，我们展示了在团聚过程中对粒子排列的控制。我们根据温度和溶剂获得了相同的烷基硫醇包覆金纳米粒子的无序和有序聚集体。我们发现有序聚集仅在配体壳的熔点以上发生。多粒子模拟表明，配体壳的接触力学主导着有序-无序转变：纯球形粒子-粒子相互作用产生有序，而配体壳之间的局部“粘连”导致无序。这表明团聚体的“粘性”和堆积可以通过配体壳的状态来切换。这表明接触力学控制着广泛的纳米粒子中的有序化。
