Department of Applied Physics, Aalto University, P.O. Box 15100, FI-02150 Espoo, Finland.
Science. 2013 Jul 19;341(6143):253-7. doi: 10.1126/science.1233775.
Self-assembly is a process in which interacting bodies are autonomously driven into ordered structures. Static structures such as crystals often form through simple energy minimization, whereas dynamic ones require continuous energy input to grow and sustain. Dynamic systems are ubiquitous in nature and biology but have proven challenging to understand and engineer. Here, we bridge the gap from static to dynamic self-assembly by introducing a model system based on ferrofluid droplets on superhydrophobic surfaces. The droplets self-assemble under a static external magnetic field into simple patterns that can be switched to complicated dynamic dissipative structures by applying a time-varying magnetic field. The transition between the static and dynamic patterns involves kinetic trapping and shows complexity that can be directly visualized.
自组装是一个相互作用的物体自主地被驱动进入有序结构的过程。静态结构，如晶体，通常通过简单的能量最小化形成，而动态结构则需要持续的能量输入来生长和维持。动态系统在自然界和生物学中无处不在，但要理解和设计它们却具有挑战性。在这里，我们通过引入基于超疏水表面上的铁磁流体液滴的模型系统，从静态自组装到动态自组装架起了桥梁。在静态外磁场的作用下，液滴自组装成简单的图案，通过施加时变磁场可以将其切换到复杂的动态耗散结构。静态和动态图案之间的转换涉及到动力学捕获，并显示出可以直接可视化的复杂性。
